Chapter 58
Immune Aspects of Infertility
Richard A. Bronson
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Richard A. Bronson, MD
Director of Andrology and Associate Professor, Obstetrics, Gynecology and Pathology, State University of New York, Health Science Center, Stony Brook, New York (Vol 5, Chap 58)

INTRODUCTION
DIAGNOSIS OF IMMUNITY TO SPERM: PRINCIPLES
DETECTION OF HUMORAL ANTISPERM ANTIBODIES
ETIOLOGY OF IMMUNE-MEDIATED INFERTILITY
EFFECTS OF ANTISPERM ANTIBODIES ON GAMETES
CLINICAL ASSESSMENT OF THE EFFECTS OF AUTOIMMUNITY TO THE SPERMATOZOA SPERMATOZOA
ETIOLOGY OF IMMUNITY TO SPERM: MEN
ETIOLOGY OF IMMUNITY TO SPERM: WOMEN
IMMUNOLOGIC REACTIONS TO SPERMATOZOA INVOLVING PREIMPLANTATION EMBRYOS PREIMPLANTATION EMBRYOS
CELL-MEDIATED IMMUNITY IN REPRODUCTION
DO ANTIZONA ANTIBODIES CAUSE INFERTILITY IN WOMEN?
VASECTOMY AND AUTOIMMUNITY TO SPERM
TREATMENT OF IMMUNITIES TO SPERMATOZOA
REFERENCES

INTRODUCTION

Spermatozoa have an unusual relationship with the immune systems of both men and women. Although they are produced by men, they bear new developmental antigens to which the male immune system is not tolerant. In women, spermatozoa periodically invade their bodies as foreigners. Spermatogenesis begins during puberty, long after the immune system has learned to distinguish the antigenic expression of its own tissues and extra-corporeal antigens. Despite the occurrence of new developmental antigens on sperm,1 an autoimmune response against spermatozoa is uncommon, occurring only in approximately 7% to 8% of unselected men from infertile couples.2

After their intravaginal deposition, spermatozoa pass through various compartments of the female reproductive tract that are capable of mounting an immune response yet fail to elicit one.3,4 Clues to both the male's and female's lack of immunologic responsiveness to sperm reside within the immune system itself. Immunosuppressive factors exist within seminal fluid, and a population of T-suppressor lymphocytes has also been detected both within seminal fluid and in the interstitium of the testis and the submucosal regions of the epididymis.5,6

It has been known since the late 19th century that spermatozoa are antigenic and that experimental animals can be immunized with sperm.7,8 In nonhuman species, these immunized animals exhibit diminished fertility.9,10,11 Although preliminary evidence suggested an association between the presence of circulating antisperm antibodies in men and women and infertility, it has only been in the past decade that many of the concepts dealing with immune-mediated reproductive impairment have been clarified.

The concept of immunologic infertility stems from several key observations. It was demonstrated in the 1950s that autoimmune responses to sperm and testis antigens had immunologic consequences. Guinea pigs immunized with homologous testis antigens in complete Freund's adjuvant developed autoimmune responses to the antigens, leading to orchitis and aspermatogenesis.12 The clinical relevance of antisperm autoimmunity became apparent in 1959, when spontaneous agglutination of ejaculated sperm and serum antisperm antibodies were observed in infertile men by Rumke and Hellinga.13 During the same period, Franklin and Dukes14 noted the presence of sperm agglutinating activity in sera of women with unexplained infertility. This was soon followed by the detection by Fjallbrant15 and Isojima and colleagues16 of serum antisperm antibodies that promoted complement-dependent sperm immobilization in infertile women. When endocrinologic problems of ovulation, sequelae of genital tract infections, and abnormalities of sperm production are excluded, there remain a substantial number of patients with idiopathic infertility. In this group, antisperm antibodies appear to have an important etiologic role.17

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DIAGNOSIS OF IMMUNITY TO SPERM: PRINCIPLES

Proof that antisperm antibodies have a role in infertility requires documentation of their presence in sera of men and women, demonstration of these immunoglobulins bound to the sperm surfaces, as well as evidence of an alteration in the ability of such immunoglobulin-coated sperm to function--that is, to enter the female reproductive tract and either to reach the site of fertilization or to fertilize eggs.

Until the late 1970s, most laboratories attempted to diagnose immunities to sperm by using one of three major forms of serologic tests: sperm agglutination (either macroscopic or microscopic), complement-dependent sperm immobilization, or indirect immunofluorescence. Although several studies documented a clear difference in the prevalence of antisperm antibodies in sera of infertile couples as compared with fertile men and women, other studies could not make this distinction between groups. The range of positive results for agglutination assays has varied from 2% to more than 30%, with a large overlap between fertile and infertile groups (Table 1). Although complement-dependent immobilization provided more discriminating power, in that the incidence of false-positive results was far lower in sera of fertile men and women, this test suffered from an inability to detect noncomplement-fixing immunoglobulins, such as IgA.18,19 Also important was the realization that naturally occurring antisperm antibodies exist in many species, including humans, at low titer. The sera of approximately 60% of men and women possess immunoglobulins that react with sperm, as detected by indirect immunofluorescence.20 These naturally occurring antibodies are readily absorbed by spermatozoa and testicular extracts but not by other human tissue. Of importance, they do not stain the surface of viable sperm in suspension but rather are directed against intracellular antigens of methanol-fixed permeabilized sperm. In one study, sera possessing antiacrosomal antibodies, when absorbed with bacteria of several species, no longer reacted with sperm. These naturally occurring antisperm antibodies have been shown to be present at only low titer (only 3 of 80 sera were positive at 1 : 16 or greater).21 In contrast to their high incidence in the general population, antibodies directed against antigens of the sperm surface, as detected by agglutination tests, mixed agglutination reaction, and immunobead binding, are uncommon and present at high titer in less than 10% of infertile men and women.22

TABLE 1. Range in Antisperm Antibodies Detected in Sera by Different Laboratories


 

Fertile (%)*

Infertile (%)

Method

Female

Male

Female

Male

Macroagglutination (GAT)

0 -37.5

0- 6.7

4.4–34.5

3.2–28.7

Microagglutination (FD or TAT)

2.7–45.8

0–10.1

5.5–41.7

2 -25.3

Complement-dependent immobilization (SIT)

0 - 5.1

0- 6.7

2.3–25

2.4–16.6


* Numbers reflect range.
GAT = gelatin agglutination test; FD = Franklin-Dukes; TAT = tray agglutination test; SIT = sperm immobilization test
(Adapted from Beer AE, Neaves WB; Antigenic status of semen from the viewpoints of the male and female. Fertil Steril 29:3, 1978. Reproduced by permission of the publisher, The American Fertility Society.)

Methods for Detecting Antisperm Antibodies on Sperm

Several methods are now clinically available to determine whether spermatozoa themselves are coated with immunoglobulins. These include a direct antiglobulin assay using 125I radiolabeled heterologous antibodies, a direct enzyme-linked immunosorbant assay (ELISA), mixed agglutination reaction, and immunobead binding.23,24,25,26 Although each of these tests allows one to determine, in a semiquantitative way, the extent of autoimmunity to sperm, immunobead binding in particular provides a measure of the proportion of spermatozoa in the ejaculate coated with each of three immunoglobulin classes (IgG, IgA, and IgM). The precise amount of immunoglobulin associated with an individual spermatozoan surface, however, still cannot be determined by current methods.

Immunobead binding uses micrometer-size plastic microspheres to which antibodies produced against human antibodies are chemically coupled.27 The antihuman antibodies on the immunobead surface bind to the human antibodies present on the sperm surface. Hence, they act as antibody detector particles, which can be visualized with an ordinary microscope. This test can be used to analyze sperm recovered from semen specimens and can be used indirectly to study serum for the presence of antisperm antibodies. In the latter case, spermatozoa must first be documented free of antibodies on their surface, by a direct immunobead assay. They are incubated in serum at various dilutions and subsequently washed free and retested to determine if they have acquired antibodies on their surface during this time. Immunobead binding allows one to determine the proportion of sperm that are coated with antibodies, the region of the sperm surface to which antibodies bind (head versus tail), and the immunoglobulin class (IgG, IgA, or IgM) of antibody present.

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DETECTION OF HUMORAL ANTISPERM ANTIBODIES

Antibodies that mediate sperm immobilization through their interaction with complement were initially described by Fjallbrant in 196815 and Isojima and colleagues in 1968.16 In these assays, sperm are washed and incubated with serially diluted heat-inactivated test serum or secretions. A source of complement. usually guinea pig serum, is added. A time end point for immobilization of 90% of sperm or the percentage of motile sperm at a standard time is compared microscopically with sperm incubated with control sera and complement alone. Complement-dependent immobilization, although highly specific in that false-positive reactions are uncommon, does not detect the presence of non-complement-fixing immunoglobulins, such as IgA. The amount of antibody present in the sperm surface also appears to have a role in the extent of complement-dependent immobilization (Table 2).19 Hence, results obtained from these tests have a definite relationship to immunologic infertility and are highly specific. However, not all antisperm antibodies are detected. In addition, because seminal plasma contains complement inhibitors, complement-dependent cytotoxicity tests cannot be applied to detection of autoantibodies to sperm in semen.

TABLE 2. Relationship Between Antisperm Antibody IgG Binding and Motility*


Extent of Antisperm Antibody

% Motility*

IgG Binding Along Sperm Tail

(Number of Sera Tested)

No binding

86.4 ± 1 (40)

Tail tip

81.1 ± 3.9 (10)

1/5 principal piece

62 ± 6.8 ( 7)

2/5 principal piece

 8 ± 3.4 (10)

3/5 principal piece

 1 ± 1 (10)


* Expressed as mean ± standard error of the mean; following a 4-hour incubation with guinea pig serum
(Adapted from Bronson RA, Cooper GW, Rosenfeld D: Correlation between regional specificity of antisperm antibodies to the spermatozoa surface and complement-mediated sperm immobilization. Am J Reprod immunol 2:222, 1982)

Agglutination tests are a relatively insensitive means of detecting antisperm antibodies, because a relatively large number of immunoglobulins must be present on the spermatozoan surface to lead to cross-linking of highly motile sperm (Table 3).28 The two main procedures for sperm immobilization are the gelatin agglutination tests of Kibrirck and colleagues29 and the microagglutination test of Friberg.30 Failure to give careful attention to controls can ultimately lead to misleading results, and nonspecific agglutination can occur in undiluted or only minimally diluted serum.31

TABLE 3. Comparison Between Results on Male Sera with Immunobead Binding Technique* (Lab 1) and Tray Agglutination Test (Lab 11)


 

Immunobead Binding Technique

 

 

Low

Intermediate

High

Tray Agglutination

Negative

Binding

Binding

Binding

Negative (titer 4)

63

19

7

11

Titer 4–8

5

5

0

1

Titer 16–32

3

1

0

3

Titer 64–128

1

0

0

4

Titer 256

2

0

0

3


* Results in immunobead binding recorded to the highest binding observed for any immunoglobulin class.
(Adapted from Bronson RA, Cooper GW, Hjort T et al: Anti-sperm antibodies detected by agglutination, immobilization, microcytotoxicity and immunobead binding assays. J Reprod Immunol 8:279, 1985)

Although a number of ELISAs had been developed to detect the presence of antisperm antibodies in serum, this approach has not proved satisfactory. A high incidence of naturally occurring sperm-reactive antibodies in the sera of fertile men and women of all ages has posed a major problem of distinguishing this immunologic background noise from those antibodies reacting with fertilization-related antigens on the sperm surface.32 The method of fixing sperm is critical in determining which antigens are presented to the test serum sample.33 A marked variation in the ability of ELISA to detect sperm-reactive antibodies has been documented when sperm were fixed in various manners (Table 4). Because this assay lends itself clinically to rapid analysis of larger numbers of sera, it has been a favorite in commercial laboratories. Results, however, have not always been shown to correlate well with clinical status.34

TABLE 4. Comparison of Antisperm Antibodies Detected by Immunobead Binding then Tested by ELISA Using Different Methods of Sperm Fixation


 

Sera Reacted First with

Sera Reacted with Fresh

Sera Reacted with

Sera Reacted with

Patient

Immunobead

Live Motile Sperm then

Sperm Glutaraldehyde

Fresh Sperm Air

Frozen Sperm

Sera

Binding Results

Glutaraldehyde Fixed

Fixed

Dried

Glutaraldehyde Fixed

 

IgG

A

M

IgG

A

M

IgG

A

M

IgG

A

M

IgG

A

M

R

+

+

-

+

+

-

+

-

+

+

+

+

+

+

+

M

+

+

+

+

+

+

+

-

+

+

-

+

+

-

+

Rm

+

+

-

+

+

-

+

-

-

-

-

-

-

-

-

E

+

+

-

+

+

-

+

+

+

+

-

+

+

-

+

B

+

+

-

+

+

-

+

+

+

+

-

+

+

-

+


The immunoglobulin classes of sperm-reactive antibodies detected by immunobead binding and ELISA were comparable only when live sperm were incubated in test serum before fixation,indicating that fixation of spermatozoa had altered their antigenicity. (detected = + ; undetected = -)
(Adapted from Bronson RA, Cooper GW, Witkin SS: Detection of spontaneously occurring sperm-directed antibodies in infertile couples by immunobead binding and enzyme-linked immunosorbent assay. Ann NY Acad Sci 438:504, 1984)
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ETIOLOGY OF IMMUNE-MEDIATED INFERTILITY

An important clue in understanding how immunities to sperm can affect reproduction was the correlation demonstrated between the titer of circulating antisperm antibodies and both the duration of time to conception and the chance of conception. Rumke and associates showed in monitoring untreated men with autoimmunity to sperm during a 15-year period that the chance of conception declined markedly when the titer of circulating antisperm antibodies rose in blood to 1 : 128 and fell to zero at titers of 1 : 1024 and greater.13 These observations suggested that as the concentration of circulating antibodies rose, the chance of their appearance in seminal fluid increased, consistent with the fact that immunoglobulins of the IgG class enter semen as transudates from serum. Autoimmunities to sperm then occur on a continuum. Their effect on an individual's fertility depends on the titer of circulating antibody, the immunoglobulin class of these antibodies, and the antibody specificity for specific antigens.

The amount of immunoglobulin bound to the sperm surface at the time of ejaculation depends on several factors: the concentration of antisperm antibodies within the prostate and seminal vesicle secretions; the local production of antibodies within the reproductive tract, compared with their transudation from blood; the binding of antibodies to sperm as they transist the epididymis before ejaculation or, conversely, when they mix with seminal fluid; the elasped time since the last ejaculation; and the affinity of different antibody molecules for various antigens on the sperm surface. Hence, the amount of immunoglobulin on the sperm surface reflects the final common pathway of several mechanisms of immunoglobulin secretion. Evidence supporting the importance of studying sperm in the ejaculate directly, in making the diagnosis of autoimmunity to spermatozoa, comes from a comparison of sperm antibodies detected in matched semen and serum specimens.35,36 In approximately 15% of cases, antibodies have been detected in serum but not on the sperm surface. The majority of these circulating antisperm antibodies that failed to enter seminal fluid were of low titer and directed against the sperm tail tip. In addition, antisperm IgM does not enter the male genital tract secretions, even when present in high concentration in blood. This immunoglobulin class of antisperm antibodies is only rarely encountered in sera of heterosexual men, though it is more common both in homosexual men and sera of women.37

Circumstantial evidence has accumulated suggesting the production of locally secreted antisperm antibodies, within the genital tract, despite their absence in blood. These immunoglobulins are primarily of the IgA class. Secretory IgA is the major immunoglobulin present in tears, saliva, and colostrum, as well as in respiratory, gastrointestinal, and reproductive tract secretions.38 It is the product of two distinct cell types. Secretory IgA is synthesized by plasma cells, and epithelial cells produce secretory component, which act as a regulatory transport protein for IgA.39 A membrane SC-IgA complex forms and is then internalized and transported to the apical region of epithelial cells. The SC-IgA complex is then released into the external secretions. Although little is known about the mechanism of IgA secretion within the male genital tract, clear evidence shows the local production of Escherichia coli-specific IgA in men with chronic prostatitis.40 A local secretory system exists in the human female reproductive tract, as suggested by the prominence of IgA-producing plasma cells in the fallopian tubes, cervix, and vagina.41 In an immunofluorescence study, Kuttah and colleagues demonstrated that tubal segments obtained at sterilization contained IgA plasma cells in the subepithelial lamina propria.42 These considerations suggest that if one relies solely on serologic tests to diagnosis immunities to sperm, results would be misleading in a sizable proportion of cases. The data enforce the notion that the presence of humoral antibodies directed against sperm is not relevant to fertility unless the circulating antibodies are present within the reproductive tract. As a corollary, tests capable of detecting immunoglobulins on living sperm recovered from the ejaculate are the most direct way to detect whether autoimmunity to sperm exists and, if so, to determine its extent and type.

The diagnosis of clinically relevant immunity to sperm in women is difficult, given our current inability to adequately sample secretions of the uterus and fallopian tubes. In addition, immunoglobulin secretion within each of the reproductive compartments (cervix, uterus, fallopian tubes) is under hormonal control and exhibits different mechanisms in the regulation of antibody transport. As an example, estradiol lowers the content of immunoglobulins within cervical mucus while stimulating the active transport of IgA and transudation of IgG into the uterine lumen.43 To add to the complexity, men may secrete blood group substances in their ejaculate, and these adsorb to spermatozoa. Antiblood group antibodies present in a woman's serum could in theory bind to these spermatozoa, giving a false-positive result. Indeed, we have presented evidence that certain antisperm antibodies of the IgM class are reactive with oligosaccharides common to the blood group substances.44 In our study of sera from known fertile women, supplied by the World Health Organization reference bank, 40% contained immunoglobulins that reacted with spermatozoa,45 usually the tail end piece. These results suggest that there is a continuum in the extent of immunity to sperm and that those mechanisms in women that prevent immunization to paternally derived antigens are imperfect. Hence, care must be exercised in distinguishing between a “positive” result and a clinically significant result, whether based on immunobead binding or any antisperm antibody assay. It is clear that results of these tests should not be interpreted in the absence of clinical correlates. This is true despite the development of better antisperm antibody assays and increasing laboratory evidence that these phenomena may lead to infertility.46

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EFFECTS OF ANTISPERM ANTIBODIES ON GAMETES

Both spermatozoa and the mature oocytes are short-lived cells that only transiently make their appearance, in a periodic manner, within the female reproductive tract. Their interaction, if successful, may lead to the development of a zygote, initiating a potential chain of events resulting in successful reproduction. The evanescent nature of gametes, however, makes them especially susceptible to immunologically mediated damage. Antisperm antibodies have been shown to be directed against several different antigens, and each would be expected to have different effects on sperm functions. At least six different major immunodominant antigens have been detected on human sperm, recognized by human sera containing antisperm antibodies.47 Indeed, several studies have shown various effects of antisperm antibodies at the level of the zona pellucida and the egg surface. Hence, we and Aitkin and colleagues have shown that antisperm antibodies might either inhibit, promote, or be neutral in their effects on the ability of human sperm to penetrate zona-free hamster eggs (Table 5).48,49 In addition, different sperm head-directed antibodies exhibit various effects on the ability of human sperm to penetrate the human zona pellucida. Using a hemizona assay, Mahony and associates assessed the effects of labeling sperm from known fertile men with antisperm antibodies.50 The power of this approach is to eliminate the variation in sperm binding between men and zonae.51 Immunobead binding was used to confirm that at the serum dilution chosen. which minimized sperm agglutination, nearly all sperm were labeled with immunoglobulin over the heads. Salt-stored hemizonas from the same egg were inseminated with antibody-free or antibody-labeled sperm from the same donor. A wide range in effect was observed, several sera markedly lowering the number of tightly bound sperm observed after serial zona washing, whereas other sera were completely without effect (Table 6). These results further emphasize that the functional effects of antisperm antibodies in different individuals may vary despite their same regional localization of binding on the spermatozoan surface. These observations emphasize the need for more specific tests that allow one to determine the antigenic moieties against which antisperm antibodies are directed.

TABLE 5. Effects of Head-directed ASA Bound to the Plasma Membrane on Sperm-Egg Penetrating Ability


 

Percentage Eggs Penetrated (Penetrating Sperm/Inseminated Egg)

Time After

 

 

 

 

Insemination

 

ASA Positive

(min)

ASA Negative

Br

Eb

Gr

90

13.3 ( 2/15)

30 ( 3/10)

0 (0/12)

100 ( 89/20)

 

 0.133

 0.3

0

  4.45

150

77.8 (11/9 )

100 (12/8)

37.5 (4/8)

100 (142/24)

 

 1.22

 1.5

 0.5

  5.91

180

92.3 (26/13)

100 (24/9 )

54.5 (6/11)

100 (113/14)

 

 2

 2.67

 0.55

 8.1

240

100 (76/23)

 

 

100 (356/28)

 

 3.3

 

 

 16.2


All experiments were performed with spermatozoa from the same known fertile donor.Each ASA-positive serum (Br, Eb, Gr) was judged against the ASA-negative control. ASA were transferred to donor sperm in vitro, and then antibody-labeled spermatozoa were washed free of serum before overnight incubation and insemination.
(Adapted from Bronson RA, Cooper GW, Phillips DM: Effects of antisperm antibodies on human sperm ultrastructure and function. Hum Reprod 4:653, 1989)

TABLE 6. Efforts of Ten Sera Containing Sperm Head-Directed Antibodies on the Ability of Human Sperm to Bind to Salt-Stored Human Zona Pellucida


 

Number

% Inhibition of

 

Serum Status

of Sera

Binding

Hemizona*Index

Antibody negative

3

1–11%

94.6 (89–99)

Antibody positive

3

<20%

87.9 (85.4–91.6)

 

2

<50%

55.3 (54.4–56.1)

 

5

>50%

30 (18.1–46.2)


*
(Adapted from Mahony MC, Blackmore PF, Bronson RA, Alexander NJ: Inhibition of human sperm-zona pellucida tight binding in the presence of antisperm antibody positive polyclonal sera. J Reprod Immunol 19:207, 1991)
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CLINICAL ASSESSMENT OF THE EFFECTS OF AUTOIMMUNITY TO THE SPERMATOZOA SPERMATOZOA

The proportion of ejaculated sperm that are coated with immunoglobulin varies markedly among men.52 For instance, in 154 men found to have autoimmunity to sperm as judged by direct immunobead binding, 52% had greater than 90% of their sperm bound, 23% had 50% to 90% bound, and the remaining quarter had less than half of their sperm coated with antibodies. Because sperm that are antibody bound over most of their surfaces are unable to enter cervical mucus53 (antibody binding to the sperm tail tip being a possible exception54), yet they remain completely motile in semen, several studies have shown a relationship between antisperm antibodies and impaired results of postcoital tests.55,56 We have found an inverse correlation between the proportion of sperm that are coated with immunoglobulin and the number of sperm present within the cervical mucus after sexual relations (Table 7). When all sperm are coated with immunoglobulin, it is rare to find one to two sperm per high-power field within well-estrogenized cervical mucus, despite the presence of hundreds of millions of motile spermatozoa in the ejaculate. However, as the proportion of antibody-coated sperm declines below 50%, as judged by immunobead binding, the numbers of motile sperm observed in cervical mucus increase. Hence, it appears that men who have high levels of autoimmunity to sperm, as reflected in the proportion of immunoglobulin-coated sperm in their ejaculates, appear to be functionally oligospermic. That is, their sperm cannot enter the reproductive tract, and the chance that they will reach the environs of the egg is diminished.

TABLE 7. Correlation Between Extent of Autoimmunity and Number of Motile Spermatozoa in Cervical Mucus at Postcoital Testing*


% Antibody-bound

 

Number of Motile

Sperm Ejaculate

Total Number of

Sperm/High-Power

Detected by

Motile Sperm in

Field in Postcoital

Immunobead Binding

Ejaculate × 106

Cervical Mucus

100%

42

0–3†

 

45

0–3

 

69

0–1

 

80

0–4

 

82

0–4

 

127

 0

 

157

0–8

 

176

0–1

 

345

 0

 

472

 0

 

638

 7

>50% but <100%

15

15

 

35

 3

 

35

2–7

 

49

 3

 

49

0–1

 

63

6–15

 

67

 4

 

715

 8

<50%

94

 7

 

118

15–40

 

150

 12

 

152

15–26

 

158

15–30


*Cervical mucus was examined within 48 hours preceding the thermal shift 8 to 12 hours after coitus. Wives were free of sperm-directed antibodies.
†Spermatozoa in cervical mucus are listed as the average observed or as a range in high-power field (x400).
(Bronson RA, Cooper GW, Rosenfeld DL: Autoimmunity to spermatozoa: Effect on sperm penetration of cervical mucus as reflected by postcoital testing. Fertil Steril 41:4, 1984. Reproduced with permission of the publisher, The American Fertility Society.)

This impairment of cervical mucus penetrating ability appears to be mediated through the Fc portion of the immunologlobulin molecule. Hence, sperm exposed to Fab preparations of antisperm IgG are able to swim through cervical mucus, whereas those labeled with intact antibody do not.57 Similarly, immunoglobulins of the IgA class bound to the sperm surface can be degraded by an IgA1 protease derived from Neisseria gonorrhoeae that cleaves the heavy chain at amino acid bond 235–236 of the hinge region.58 In this manner, the Fc portion of IgA is liberated from the sperm surface. These protease-treated sperm, although still coated with IgA Fab, showed an improved ability to penetrate into and sustain motility within cervical mucus (Table 8). On this basis, we have postulated that a solid-phase component of cervical mucus possesses a yet unidentified receptor for a ligand on the Fc portion of the immunoglobulin molecule. That this effect is not species specific was demonstrated in a study of the effects of a number of antisperm monoclonal antibodies, raised in mice, on the ability of human sperm to penetrate bovine cervical mucus in vitro.59 Those monoclonal antibodies directed against epitopes present on the living sperm surface (as detected by immunobead binding) impaired sperm penetration through a column of bovine cervical mucus, whereas monoclonal antibodies directed against subsurface epitopes (detected by indirect immunofluorescence with permeabilized sperm) did not (Table 9).

TABLE 8. Effect of IgA1 Protease Treatment Promoting the Mucus-Penetrating Ability of Coated Human Spermatozoa


 

 

Percent of Motile Sperm Penetrating a

 

 

Column of Human Cervical Mucus In

Patient

 

Vitro

Identification

Antisperm Antibody Isotype

Pretreatment

After Protease

Nel

IgG > IgA

2%

2%

Tm

IgA > IgG

4%

4%

Bu

 IgA

4%

13%

F

IgA = IgG

4%

12%

Ng

IgA >> IgG

4%

23%

Sm

IgA > IgG

13%

31%

Ba

IgA >> IgG

3%

20%

Chr

 IgA

14%

24%

Ru

 IgA

31%

48%

006

Antibody negative

24.5%

15.4%

135

Antibody negative

24.7%

28%

023

Antibody negative

27.1%

21.8%

(Adapted from Bronson RA, Cooper GW, Rosenfeld DL et al: The effect of an IgA1 protease on immunoglobulins bound to the sperm surface and sperm cervical mucus penetrating ability. Fertil Steril 47:987, 1987. Reproduced with permission of the publisher, The American Fertility Society.)

TABLE 9. Relationship Between the Extent of Binding of Monoclonal Antibody to Motile Spermatozoa and Their Ability to Penetrate Bovine Cervical Mucus In Vitro


Mab Reactivity as Judged

 

Location of Vanguard

by % Sperm Binding

Number of

Spermatozoa (mm)

Immunobeads*

Samples

+ SD†

100% sperm bound

11

17.5 ± 6.2

50 < 100%

7

27.3 ± 11.8

<50%

6

33.0 ± 11.7

No binding

12

37.4 ± 5.8


* A population of nearly 100% motile spermatozoa obtained by swim-up were incubated with monoclonal antibody then washed free of ascitic fluid or culture supernatant and exposed to immunobeads.
† Following 90 minutes incubation at 37°C.
(Adapted from Bronson RA, Cooper GW: Effects of sperm-reactive monoclonal antibodies on the cervical mucus penetrating ability of human spermatozoa. Am J Reprod Immunol 14:59, 1987)

The presence of antisperm antibodies in women may also be associated with altered sperm motion within cervical mucus. Spermatozoa appear initially to gain entrance into the cervical mucus but then subsequently become immobilized, either by shaking in place, without forward progression, or being completely immobilized. The behavior of sperm within cervical mucus depends on the type of antibodies present within the mucus and their specificity for the sperm surface. Hence, high degrees of binding of non-complement-fixing antibodies to the sperm surface may result in sperm entrapment and shaking in place, whereas complement-fixing antibodies (when directed against the majority of the sperm tail) could also lead to immobilization. Levels of complement within cervical mucus are lower than those present in serum,60 and in fact, it may take as long as 6 to 7 hours for sperm immobilization to occur. Hence, overnight postcoital testing provides a clearer indication of antibody-mediated sperm damage than does a shorter interval (2 hours) after sex.

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ETIOLOGY OF IMMUNITY TO SPERM: MEN

During the onset of spermatogenesis, at puberty, new developmental antigens make their appearance on the sperm surface.61 As immune tolerance for self-antigens is established in the neonatal period, these newly appearing sperm antigens may be immunogenic. It has been theorized that sequestration of developing sperm, behind the blood-testis barrier formed by tight junctions of Sertoli cells, prevents the generation of autoantibodies to sperm.62 Additional evidence now indicates that some testicular autoantigens are accessible to circulating antibodies and to immune processing cells.63,64 A population of suppressor T lymphocytes has been identified in the epididymis by immunoperoxidase staining with monoclonal antibody probes to T-cell surface antigens.5,6 These putative T-suppressor lymphocytes may have an active role in preventing the development of autoimmunity to sperm.

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ETIOLOGY OF IMMUNITY TO SPERM: WOMEN

Although women are regularly “inoculated”intravaginally with spermatozoa during coitus. this event is usually not associated with the development of immunity to sperm. Yet. the female reproductive tract is not an immunologically privileged site, as demonstrated by the presence of anti-Candida antibodies in women with yeast vaginitis.3 Experimental intravaginal inoculation with poliovirus in women has been shown to lead to the formation of locally produced antiviral antibodies in vaginal secretions.4

Immunoinhibitory substances have been detected and partially characterized in seminal plasma; they may protect sperm from immunologic damage and prevent sensitization of a woman to sperm antigens after coitus.65,66 19-Hydroxy prostaglandin E, a potent immunosuppressive agent. has been found in seminal fluid of men and subhuman primates.67 Other possible immunosuppressive factors include polyamines,68 transglutaminase,69 and high-molecular-weight Fc receptor binding protein similar to pregnancy-associated protein A.70 Spermatozoa themselves have been shown to be immunosuppressive in rodents.71 However, because semen samples in vasectomized males also exhibit immunosuppressive activity, this observation suggests that active components are derived not solely from testicular, epididymal. or spermatozoan origin. Extensive studies on fractions obtained by gel filtration of seminal fluid and chromatographic techniques support the view that the inhibitory effects of seminal plasma are due to a range of molecules of widely different molecular weights and binding affinities for specific ligands. Research in this area has been difficult because of the diversity of immunomodulatory substances and the tendency of low-molecular-weight species to associate reversibly with high-molecular-weight components. The generation of cytotoxic polyamines, following addition of calf serum to seminal plasma, in studies of immunosuppressive activity has further confused the issue.72 However, using serum-free culture conditions illustrates clear evidence of interference by seminal fluid in the immune function of T cells, B cells, and NK cells and macrophages.73 The effects of human seminal plasma on immunologically active cells include a reduced ability to bind antigen and to differentiate or proliferate in response to mitogens, as well as a failure of phagocytosis in antibody-dependent cell lysis. Anticomplement activities have also been demonstrated.74 Could nature then provide the means through the common exposure at coitus to seminal fluid-derived suppressors. as well as spermatozoa, to prevent the development of immunity of sperm in women? Conversely, would the lack of immunosuppressor activity, of seminal fluid lead to the development of antisperm antibodies? These intriguing questions. unfortunately. currently have no answer.

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IMMUNOLOGIC REACTIONS TO SPERMATOZOA INVOLVING PREIMPLANTATION EMBRYOS PREIMPLANTATION EMBRYOS

Evidence that spermatozoa share antigenic specificities with fertilized ova or cleaving embryos was initially provided experimentally in female animals immunized with sperm or testis cells. At serum dilutions permitting nearly normal fertilization rates, antisperm antiserum impaired embryo survival.75 Postfertilization effects of antisperm antiserum have also been demonstrated by the reduced survival of fertilized eggs transferred from oviducts of nonimmune rabbits to those of immunized pseudopregnant females.76 Uterine implantation rates of these embryos were one third to one half those in nonimmunized controls. In rabbits. antibodies raised against murine sperm have also been shown to react with early cleavage-stage mouse embryos77 and a number of antisperm monoclonal antibodies have been shown to react with antigens present on trophoblast cells.78

In theory. three mechanisms could account for the effects of experimentally induced antisperm antibodies and preimplantation embryo survival. Eggs may display sperm-derived antigens on the oolemma after fertilization.79 Embryonic antigens cross-reacting with sperm may be expressed during early embryonic development.80 Antisperm antibodies may indirectly affect embryonic development by stimulating the production of cytotoxic lymphokines from activated lymphocytes in the immune system of women sensitized to sperm.81

Although an anecdotal association between an increased risk of miscarriage and the presence of antisperm antibodies in women has been reported,82 there is at this time no clear evidence in humans that antisperm immunity causes abortions in clinically diagnosed pregnancies. For example, the risks of miscarriage in women who have antisperm antibodies and who conceive after intrauterine insemination (IUI) have been found to be no greater than in the general infertile population.83 However. these observations do not address the question of whether antisperm immunity can cause abortion during the interval between ovulation and implantation. Because pregnancy would not be clinically diagnosed in these cases, the manifestations of this event would be occult and would present as unexplained infertility rather than recurrent abortion. A single study of the likelihood of successful preimplantation embryonic development and subsequent pregnancy, in women with immunologic infertility undergoing in vitro fertilization (IVF), again raises this issue (see below).

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CELL-MEDIATED IMMUNITY IN REPRODUCTION

Reproductive tract tissues contain diverse lymphocyte and macrophage populations, which can be activated and may alter reproductive functions. Increasing evidence suggests that soluble products of these cells can either inhibit or promote various endocrine, gamete, and nidatory events.84 Cell-mediated immunologic responses involve thymus-derived lymphocytes that are activated by antigenic stimulation and immunologic cytokines. Cytotoxic T cells can recognize and kill cells bearing foreign antigens by direct contact and by release of cytotoxic cytokines such as interferon gamma. Both the endometrium in the late luteal phase of the menstrual cycle and the decidua of early pregnancy contain numerous lymphocytes and macrophages.85,86 Several studies have reported antisperm cell-mediated immune responses in infertile women. One study of endometrial T-cell subpopulations in infertile patients has revealed large numbers of activated T cells in some of these women.87 Patients with endometriosis have been found to have large numbers of activated macrophages and lymphocytes in their peritoneal fluid.

Soluble products of activated lymphocytes and macrophages, including the lymphokine interferon gamma and the monokine tumor necrosis factor, have been shown to affect human sperm motility and fertilization, as measured by the hamster egg penetration test.88 Secretion of these products and others within various regions of the female reproductive tract could affect sperm function. Various lymphokines and monokines have also been reported to exert adverse effects on the development of early mouse embryos in vitro?

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DO ANTIZONA ANTIBODIES CAUSE INFERTILITY IN WOMEN?

Given evidence that impaired infertility can be induced experimentally by either active or passive immunization with zona pellucida proteins,90,91,92 several groups have attempted to determine whether such antibodies occur spontaneously in women.93,94,95,96 Unfortunately, problems of methodology have continued to result in a failure to prove this thesis convincingly. Because the zona pellucida consists of a glycoprotein matrix capable of trapping immune complexes, the use of immunofluorescence to detect specific antibodies to intact zona antigens may lead to nonspecific reactions. Dunbar has shown that the production of immune complexes by freezing and thawing serum can give false-positive reactions from previously negative serum.97 Unfortunately, the majority of studies of humans have also used relatively undiluted serum, without concern for the specificity of the assay. Clinical studies have been diverse and contradictory (Table 10).94a,96a Dunbar studied sera from many infertile women using a sensitive radioimmunoassay with well-characterized, purified zona antigens and failed to detect any antizona antibodies.97 Although it could be argued that these purified zona antigens have undergone alterations in their configuration such that native epitopes were lost, the presence of antizona autoantibodies in humans has not been confirmed.

TABLE 10. Incidence of Anti-Zona Pellucida Antibodies in Sera of Fertile and Infertile Women and Men


 

 

Clinical Category

Investigators

Method of Antibody

and Incidence of

and Citation

Detection

Positive Sera

Shivers CA, Dunbar

Indirect immunofluorescence

Infertile women 7/22 “Control sera”

 RS93

 with whole porcine zonae

 

Sacco AG, Moghissi

Indirect immunofluorescence

Infertile females 21/50

 KS94

 with whole porcine zonae

Fertile females 18/30

 

 

Infertile males 18/35

 

 

Fertile males 4/10

Karuchi H, Wakimoto

Heat-solubilized 125I-labeled

Women with unexplained infertility 3/11

 H, Sakumoto T et 94a

 porcine zonae

 

 

 

Women with amenorrhea 16/48

 

 

Fertile women 4/12

 

 

Fertile men 3/10

Kamada M, Hasehe H,

Passive hemagglutination with

Infertile women 8/88*

 Irahara M et al96

 bovine erythrocytes coated

Fertile women 1/90

 

 with porcine zona substance

 * All reactivity detected by

 

 

 passive hemagglutination

 

 

 lost after absorption of sera

 

 

 with porcine erythrocytes

Dakhno FU, Hjort T,

Indirect immunofluorescence

Fertile women 5/20

 Grischenko 96a

 with whole porcine zonae

Women with unexplained infertility 7/24

 

 

Fertile males 6/11

 

 

Reactivity in all groups absorbed with

 

 

 porcine erythrocytes

Dunbar B97

ELISAs against purified porcine

No reactivity detected in sera

 

 zona antigens

 of infertile women

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VASECTOMY AND AUTOIMMUNITY TO SPERM

Vasectomy, by inhibiting sperm exit from the epididymis and proximal vas deferens, results in sperm antigen leakage and antisperm antibody production in approximately 70% of men.98,99 The presence of circulating antibodies to continuously produce sperm antigens has raised the concern that vasectomy might result in immune complex disease.100 Immunologically immediated injury occurs when preformed immune complexes are deposited either in renal glomeruli or blood vessel walls. That an immune response need not be mounted for damage to occur has been shown when arteritis, endocarditis, and glomerulonephritis developed in normal animals infused with immune complexes. The formation of circulating immune complexes is dependent on both antigen and type of antibody (numbers of combining sites, size of immunoglobulin molecule, and molecular weight and charge of antigen). Large complexes formed in antibody access are rapidly removed, primarily by the Kupffer's cells of the liver. in contrast, complexes formed in antigen access will be of smaller size and may remain in the circulation. These may become widely disseminated and activate the complement cascade.101

Alexander has shown that antigen production continues after vasectomy and that entrapped sperm are engulfed by macrophages within the vas deferens.102 Sperm antigens may also leak from the reproductive tract. The efferent ducts of the testis in monkeys vasectomized 1 year earlier were found to have a significant increase in thickness, and 33% of these animals exhibited immune complexes within the thickened basement membrane.103 Granular deposits of both IgM and IgG, as well as the complement component C3, have been found in renal glomeruli of vasectomized animals. Vasectomized men have also been shown to have a higher incidence of circulating immune complexes than age-matched controls.104 Although some monkeys fed diets high in cholesterol after vasectomy developed atherosclerosis,105 several epidemiologic studies in humans have failed to substantiate an increased risk.106,107 However, a 2.6-fold increased risk of acute myocardial infarction has been documented recently in vasectomized men.108

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TREATMENT OF IMMUNITIES TO SPERMATOZOA

Effective treatment of immunities to sperm rests on the accuracy of diagnosis. Four approaches have been used to treat couples with antisperm antibodies. Condom “therapy” is mentioned only to emphasize its ineffectiveness, in the presence of more active treatment approaches.109 Its value was never clearly documented in the past, and the psychological burden of using contraception when desiring pregnancy is great. The remaining approaches have included corticosteroids, IUI, and IVF, and gamete intrafallopian transfer (GIFT). However, the risk: benefit ratio in the use of corticosteroids is still not well known for either men or women. Preliminary evidence suggests that this treatment approach is relatively ineffectual. IUI, when carefully timed to follicular maturation in superovulated and hormonally and sonographically monitored cycles, results in an increased chance of pregnancy, but success rates at best are no greater than 35% within six treatment cycles. Although technically intense and expensive, if IUI fails, IVF offers the greatest likelihood of achieving fertilization, in the presence of both autoantibodies to sperm in men and circulating antisperm antibodies in women. Early evidence indicates that GIFT may also be effective in treating couples in whom the man has developed antisperm immunity.110

These results with the newer assisted reproductive techniques suggest that immunities to sperm impair the ability of spermatozoa to reach the site of fertilization within the fallopian tubes to a far greater extent than their ability to penetrate eggs, should the gametes meet in the presence of these antibodies.

In 1976, Shulman reported the successful use of corticosteroids to treat a man with autoimmunity to sperm.111 Although various degrees of success have subsequently been described, most of these earlier reports suffer from their inability to document the change in antibody binding on the sperm themselves (Table 11).111a,112,112a,113,114,115,116 Success of treatment was often not judged on the basis of an observed quantitative change in the status of autoimmunity but rather on the rate of pregnancy following treatment. However, in retrospectively analyzing the pregnancy outcome of 108 women whose mates were found to have autoimmunity to sperm but were not treated during a 2-year period, spontaneous conception rates varied with the proportion of sperm antibody coated.115 When more than 50% of sperm were bound with immunoglobulins, 22% of women conceived, whereas 45% conceived when less than 50% of sperm in the ejaculate were immunoglobulin coated. The results were even more distinct in couples whose sole cause of infertility was the man's autoimmunity to sperm. Here, pregnancy rates were 15.6% if the majority (more than 50%) of sperm were antibody coated and rose to 63% if less than 50% of sperm were bound. Given these well-documented spontaneous conception rates, depending on the extent of autoimmunity to sperm, the use of pregnancy as a validation of treatment is misleading, without adequate placebo controls.

TABLE 11. Pregnancy Rates After Corticosteroid Treatment of Men with Immunity to Spermatozoa


 

 

Number of Pregnancies (%)

Investigators and Citations

Treatment

Number of Men Treated

DeAlmeida M, Jouannet P116

Dexamethasone, 2 or 3 mg/

3/14 (21%)

 

 day × 9–13 weeks, then 7

 

 

 weeks taper

 

Hendry W et al111a

Methylprednisone, 96 mg/day

14/45 (35%)

 

 × 7 days starting on CD*

 

 

 21 of wife's menstrual

 

 

 cycle

 

Hargreave T, Elton RA112a

Methylprednisone, 96 mg/day

5/13 (38%)

 

 × 7 days starting on CD 21

 

 

 of wife's menstrual cycle

 

Shulman S, Shulman J112

Methylprednisone, 96 mg/day

31/71 (44%)

 

 × 7 days starting on CD 21

 

 

 of wife's menstrual cycle

 

Hendry W et al113

Prednisolone, 20 or 40 mg

25/76 (33%)

 

 twice a day on CD 1 of

 

 

 wife's menstrual cycle;

 

 

 then 5 mg/day on CD 11

 

 

 and 12 for 9–12 cycles

 

Alexander NJ, Sampson

Prednisolone, 20 mg 3 times/

7/19 (37%)

 JH, Fulgham DL114

 day

 

 Ayvaliotis B et al115

No treatment over 2 years

(21.8%)†

 

 retrospective period of

(43.4%)‡

 

 observation

 


* CD = cycle day
† Greater than 50% of sperm antibody coated as determined by direct immunobead binding.
‡ Less than 50% of sperm antibody coated.

A single study has documented a variable suppression of antisperm antibodies within seminal plasma in some men treated with corticosteroids.116 A single study has also reported changes in the amount of antibody bound to sperm.117 Whether the degree of suppression of autoimmunity in these cases would be sufficient to increase the number of antibody-free sperm in the ejaculate to a clinically significant level remains unproven. Given the side-effects of corticosteroids, such as mood changes, leg muscle cramps, hypertension, reactivation of ulcers, alterations of glucose tolerance, and rare but severe aseptic hip joint necrosis, one must currently remain conservative about their use pending further well-controlled studies.

A rationale for IUI is to place within the uterine cavity a large population of living sperm that were excluded after coitus because of the presence of antisperm antibodies either on their surface or within cervical mucus. in theory, this would increase the likelihood that sperm might enter the fallopian tubes and reach the egg. Using careful sonographic and hormonal monitoring of follicular maturation, insemination can be timed to within a few hours of the expected ovulation. The accuracy of timing is theoretically important in that antibody-bound spermatozoa have a shortened survival time within the female reproductive tract. Pregnancy rates have varied in different clinical series over the range of 20% to 40%. Conception occurred rapidly within four to six cycles, as in the case of women without antisperm antibodies,118,119 and appeared to be higher in gonadotropin-stimulated cycles (Table 12).83,120 These studies have been difficult to interpret, unfortunately, because the diagnosis of immune-mediated infertility is often unclear. Hence, the association of circulating antisperm antibodies in sera of women, in conjunction with impaired sperm survival within cervical mucus, is not necessarily proof of a cause-and-effect relationship. The clinical data do suggest, however, that this approach should be attempted before IVF. In addition, given the relatively low conception rates, these results suggest that antibody-coated sperm may not always reach the fallopian tubes after IUI, despite their placement high within the uterine fundus. Alternatively, they may be unable to fertilize, despite successfully meeting the egg at the site of fertilization, because of the presence of antisperm antibodies in tubal secretions.

TABLE 12. Conception Rates Per Cycle Following IUI in Women with Humoral Antisperm Antibodies and Impaired Postcoital Tests*


 

Number of Pregnant/Number of Inseminated (% Pregnant)

 

 

 

Human Menopausal

Cycle Number

Natural Cycle

Clomiphene Citrate

Gonadotropins

1

4/67

2/25

5/28

 

(6%)

(8%)

(18%)

2

5/62

4/23

1/20

 

(8%)

(17%)

(5%)

3

0/47

0/14

3/15

 

 

 

(20%)

4

0/38

0/9

1/11

 

 

 

(9%)

5

0/24

0/7

1/8

 

 

 

(12%)

6–10

0/47

 

0/20


* Fewer than 5 motile sperm per high-power field
(Adapted from Margalioth EJ, Sauter E, Bronson RA et al: Intrauterine insemination as treatment for antisperm antibodies in the female. Fertil Sterile 50:444, 1988. Reproduced with permission of the publisher, The American Fertility Society.)

If IUI fails, IVF currently appears to offer the best chance of conception in couples with documented immunities to sperm. Antisperm antibodies within follicular fluid can be removed by washing the cumulus oocycte complex, and any residual immunoglobulins that may remain within the cumulus oophorus that surrounds the egg do not usually appear to interfere with sperm penetration. IVF in women with antisperm antibodies has been anecdotally reported to be successful at rates comparable to those in their absence.121,122,123 However, a more critical examination of the results of IVF in women with immunities to sperm has now revealed a diminished fertilization rate, embryonic cleavage rate, and ultimate pregnancy rate.124 This study used bovine serum albumin (BSA) in the culture medium in lieu of the patient's serum if significant levels of antisperm antibodies were present. Fertilization and embryo cleavage rates, as well as pregnancy rates, were compared with those in women in the absence of antibodies, but also in the presence of BSA. In the immune infertile group, 44% of eggs (251 of 569) were fertilized in 50 cycles, versus 74.2% and 75.1% for the maternal serum and BSA controls, respectively. The percent of high-quality embryos was 49% for the immunologic infertile group versus 78% and 74% for the controls. Ten clinical pregnancies occurred in the former group versus 18 and 19 in the latter. Although promising in that they illustrate that significant pregnancy rates can be achieved in these couples despite the presence of antisperm antibodies, these results suggest that either these antibodies cannot be eliminated from the egg by washing, hence impairing fertilization, or that they may be egg cytotoxic.

In men with autoimmunity to sperm, the diminished number of antibody-coated sperm within cervical mucus after coitus markedly lowers the chances that the gametes will meet. IVF circumvents this problem of sperm transport and ensures the meeting of spermatozoa and egg. In contrast to women with immunities to sperm. however. in whom follicular fluid containing antisperm antibodies can be washed from the egg, immunoglobulins in the ejaculates from men with autoimmunity to sperm remain bound to the sperm surface after their recovery from seminal fluid.125 Although antibodies present on the sperm tail do not appear significantly to prevent fertilization in vitro, sperm head-directed antibodies have the potential to alter the spermatozoan egg-penetrating ability, as previously described in both the hemizona assay and the zona-free hamster egg penetration test. Fortunately, these effects only become apparent when more than 75% of the sperm population used in IVF are coated with immunoglobulins (Table 13).126,127 If more than one quarter of sperm recovered in semen for IVF are free of antisperm antibodies, the likelihood that fertilization rates will not be impaired is high. Results also depend on the sperm antigen to which these antibodies are directed. In other words, should the antibodies be directed against antigens that have no role in fertilization, the process of penetration by the spermatozoon would not be impaired. This has clearly been documented after the generation of antisperm monoclonal antibodies, under experimental conditions.128,129 Unfortunately, no clinical test can predict this outcome before an actual attempt at IVF. As a technique to minimize the amount of antibody binding on sperm after ejaculation, it appears to be desirable clinical practice to produce the semen specimen directly on hospital premises, requesting ejaculation directly into a washing buffer.130 This appears beneficial in terms of both maximizing sperm recovery and minimizing the amount of antibody coating sperm. Finally, the number of spermatozoa placed in culture with eggs for IVF can also be increased, in an attempt to increase the likelihood of fertilization.125,131 Because the percent of eggs fertilized by antibody-coated sperm may be diminished, the use of hormonal stimulus protocols leading to the formation of a greater number of mature follicles yielding fertilizable eggs would also increase the likelihood that some of these eggs would be fertilized. In those instances in which spermatozoa failed to attach to and penetrate the zona pellucida, preliminary studies have suggested that fertilization may be successful by partial zona dissection132 or subzonal microinjection133 of antibody-labeled sperm into the perivitelline space surrounding the egg. However, it should be emphasized that the effectiveness and safety of these procedures still need to be clearly documented.134,135

TABLE 13. Effect of Antisperm Antibodies on In Vitro Fertilization Rates in 32 Men with Autoimmunity to Spermatozoa


 

Percent Spermatozoa Coated with Immunoglobulin*

 

>80% IgA & IgG

>80% IgA

>80% IgG

<80% IgA & IgG

Percent Eggs Fertilized

25% (102)

30% (10)

89% (29)

73% (75)

 (No. of Eggs Inseminated)

 

 

 

 


*As determined by direct immunobead binding.
(Adapted from DeAlmeida M, Gazagne I, Jeulin C et al: In vitro processing of sperm with auto-antibodies and in vitro fertilization results. Hum Reprod 4:49, 1989 and Clarke GN, Lopata A, McBain JC et al: Effect of sperm antibodies in males in human in vitro fertilization (IVF). Am J Reprod Immunol 8:62, 1985)
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REFERENCES

1. Tung KSK, Menge AC: Sperm and testicular autoimmunity. In Rose NR, MacKay R (eds): The Autoimmune Diseases. pp 537–590. New York, Academic Press, 1985

2. Clarke GN, Elliot P, Smala C: Detection of sperm antibodies in semen using the immunobead test: A survey of 813 consecutive patients. Am J Reprod Immunol 7: 118, 1985

3. Ogra PH, Ogra SS: Local antibody response to polio vaccine in the human female genital tract. J Immunol 110: 1307, 1973

4. Waldman RLT, Cruz JM, Rone FS: Immunoglobulin levels and antibody to Candida albicans in human cervico-vaginal secretions. Clin Exp Immunol 10: 427, 1972

5. El-Demiry M, James R: Lymphocyte subsets and macrophages in the male genital tract in health and disease. Eur J Urol 14: 226, 1988

6. Witkin SS: Mechanisms of active suppression of the immune response to spermatozoa. Am J Reprod Immunol 17: 61, 1988

7. Bratanov K: Reproductive immunology: Historical roots, achievements and prospects. In Isojima S, Billington WD (eds): Reproductive Immunology, pp 1–18. New York. Elsevier, 1983

8. Edwards RG: Immunologic control of fertility in female mice. Nature 203:50 1963

9. Katsh S: Infertility in female guinea pigs induced by injection of homologous sperm. Am J Obstet Gynecol 78: 276, 1959

10. McLaren A: immunologic control of fertility in female mice. Nature 201: 583, 1964

11. Menge AC, Peegel H, Riolo ML: Sperm factors responsible for immunologic induction of pre and post fertilization infertility in rabbits. Biol Reprod 20: 93, 1979

12. Freund J, Lipton MM, Thompson GE: Aspermatogenesis in the guinea pig induced by testicular tissue and adjuvants. J Exp Med 97: 711, 1952

13. Rumke P, Hellinga G: Auto-antibodies to spermatozoa in sterile men. Am J Clin Pathol 32: 357, 1959

14. Franklin RR, Dukes CD: Antispermatozoal antibody and unexplained cases of sterility in women. Am J Obstet Gynecol 89: 6, 1964

15. Fjallbrant B: Sperm antibodies and sterility in men. Acta Obstet Gynecol Scand (suppl) 47: 89, 1968

16. Isojima S, Li TS, Ashitaka Y: Immunologic analysis of sperm immobilizing factor found in sera of women with unexplained infertility. Am J Obstet Gynecol 101: 677, 1968

17. Bronson RA, Cooper GW, Rosenreid DL: Sperm antibodies: Their role in infertility. Fertil Steril 42: 171, 1984

18. Cooper NR: The complement system. In Stites DP, Stobo JB, Wells JV (eds): Basic and Clinical Immunology, 6th ed, pp 114–127. Norwalk, Appleton & Lange, 1987

19. Bronson RA, Cooper GW, Rosenreid DL: Correlation between regional specificity of antisperm antibodies to the spermatozoan surface and complement-mediated sperm immobilization. Am J Reprod Immunol 2: 222, 1982

20. Tung KSK, Cooke WD Jr, McCarthy TA et al: Human sperm antigens and antisperm antibodies. Part 11. Age related incidence of antisperm antibodies. Clin Exp Immunol 25: 72, 1976

21. Hjort T, Hansen RB: Immunofluorescent studies on human spermatozoa, Part I. The detection of different spermatozoal antibodies an their occurrence in normal and infertile women. Clin Exp Immunol 8: 9, 1971

22. Landers DV, Bronson RA, Pavia CS: Reproductive Immunology. In Stites DP, Terr AI (eds): Basic Human Immunology, pp 200–216. Norwalk, Appleton & Lange, 1990

23. Haas GG Jr, D'Cruz OJ: Quantitation of immunoglobulin G on human sperm. Am J Reprod Immunol 20: 37, 1989

24. Jager SS, Kremer J, Van Slochteren-Draaisma T: A simple method of screening for antisperm antibodies in the human male: Detection of spermatozoal surface IgG with the direct mixed agglutination reaction carried out in the untreated fresh human semen. Int J Fertil 23: 12, 1978

25. Bronson RA, Cooper GW, Rosenfeld DL: Membrane-bound sperm specific antibodies. Their role in infertility. In Vogel H, Jagiello G (eds): Bioregulators in Reproduction. p 526. New York, Academic Press, 1981

26. Clarke GN, Stojanoff A, Cauchi MN: Immunoglobulin class of sperm-bound antibodies in semen. In Bratanov K (ed): Immunology of Reproduction. pp 482–485. Sophia, Bulgarian Academy of Sciences Press, 1982

27. Bronson RA: Immunobead binding: Present and future uses. In Mathur S, Fredricks C (eds): Perspectives in Immunoreproduction. p 102. New York, Hemisphere, 1988

28. Bronson RA, Cooper GW, Hjort T et al: Antisperm antibodies detected by agglutination immobilization, microcytoxicity and immunobead binding assays. J Reprod Immunol 8: 279, 1985

29. Kibrick S, Belding DL, Merrik B: Methods for the detection of antibodies against mammalian spermatozoa. Part II. A gelatin agglutination test. Fertil Steril 3: 430, 1952

30. Friberg J: Immunological studies on sperm agglutinating sera from men. Acta Obstet Gynecol Scand (suppl) 36: 43, 1974

31. Rose NR, Hjort T, Rumke P et al: Techniques for detection of iso- and autoantibodies to human spermatozoa. Clin Exp Immunol 23: 175, 1976

32. Mettler L, Czuppon AB, Alexander N et al: Antibodies to spermatozoa and seminal plasma antigens detected by various enzyme-linked immunosorbent (ELISA) assays. J Reprod Immunol 8: 30, 1985

33. Bronson RA, Cooper GW, Witkin SS: Detection of spontaneously occurring sperm-directed antibodies in infertile couples by immunobead binding and enzyme-linked immunosorbent assay. Ann NY Acad Sci 438: 504, 1984

34. Clarke GN: Lack of correlation between the immunobead test and the enzyme-linked immunosorbent assay for sperm antibody detection. Am J Reprod Immunol 18: 44, 1988

35. Pavia CS, Stites DP, Bronson RA: Reproductive immunology, In Stites DP, Stobo JD, Wells JU (eds): Basic and Clinical Immunology. 6th ed. p 619. Norwalk, Appleton & Lange, 1987

36. Hellstrom WJG, Overstreet JW, Samuels SJ et al: The relationship of circulating antisperm antibodies to sperm surface antibodies in infertile men. J Urol 140: 1039, 1988

37. Bronson RA, Cooper GW, Rosenfeld DW et al: Comparison of antisperm antibodies in homosexual and infertile men with auto-immunity to spermatozoa. Presented at the 30th annual meeting of the Society for Gynecologic Investigation, Washington, DC. March 17–20, 1983

38. Mesteky J, McGhee JR: Immunoglobulin A (IgA): Molecular and cellular interactions involved in IgA biosynthesis and immune response. Adv Immunol 40: 153, 1987

39. Wira CR, Stern JE: Endocrine regulation of the mucosal immune system in the female reproductive tract: Control of IgA, IgG and secretory components during the reproductive cycle, at implantation and throughout pregnancy. in Pasqueline R, Scholler R (eds): Hormones and Fetal Pathophysiology, New York, Marcel Decker, (in press)

40. Fowler JE Jr, Mariano M: Immunologic response of the prostate to bacteriuria and bacterial prostatis, Part II. Antigen specific immunoglobulin in prostatic fluid. J Urol 128: 105, 1982

41. Kutteh WH, Hatch KD, Blackwell RE et al: Secretory immune system of the female reproductive tract, Part I. Immunoglobulin and secretory component-containing cells. Obstet Gynecol 71: 56, 1988

42. Kutteh WH, Blackwell RE, Gore H et al: Local immune system in normal and infected human fallopian tube. Fertil Steril 54: 55, 1990

43. Wira CR, Sandoe CP: Specific IgA and IgG antibodies in the secretions of the female reproductive tract: Effects of immunization and estradiol on expression of this response in vivo. J Immunol 138: 4159, 1987

44. Cooper GW, Bronson RA: Characterization of humoral antibodies reactive with spermatozoa, N-acetyl galactose-amine and a putative blood group antigen in seminal plasma. Fertil Steril 53: 888, 1990

45. Bronson RA, Cooper GW, Rosenreid DL: Sperm antibodies: Their role in infertility. Fertil Steril 42: 171, 1984

46. Bronson RA, Tung KSK: Spermatozoa antibodies: Detection and clinical significance. In Tan E (ed): Laboratory Manual of Clinical Immunology. (in press)

47. Primakoff P, Lathrop W, Bronson RA: Identification of human sperm surface glycoproteins recognized by autoantisera from immune infertile men, women and vasectomized men. Biol Reprod 42: 929, 1990

48. Bronson RA, Cooper GW, Phillips DM: Effects of antisperm antibodies on human sperm ultrastructure and function. Hum Reprod 4: 653, 1989

49. Aitkin RJ, Hulme MJ, Henderson CT et al: Analysis of the surface labelling characteristics of human spermatozoa and the interaction with antisperm antibodies. J Reprod Fertil 80: 473, 1987

50. Mahoney MC, Blakemore PF, Bronson RA, Alexander N J: Inhibition of human sperm: Zona pelluida tight binding in the presence of antisperm antibody positive polyclonal patient sera. J Reprod Immunol 19: 287, 1991

51. Burkman LJ, Coddington CC, Franken DR et al: The hemizona assay (HZA), development for the binding of human spermatozoa to the human hemizona pellucida to predict fertilization potential. Fertil Steril 49: 608, 1988

52. Bronson RA: Immunologic infertility. In Rajfer J (ed): Infertility and Impotence, pp 93–100. Chicago, Year Book Medical Publishers, 1990

53. Jager S, Kremer J, Kuiken J et al: Induction of the shaking phenomenon by pretreatment of spermatozoa with sera containing antisperm antibodies. Fertil Steril 36: 784, 1984

54. Wang C, Baker HWG, Jennings MG et al: Interactions between cervical mucus and sperm surface antibodies. Fertil Steril 44: 484, 1985

55. Bronson RA, Cooper GW, Rosenfeld DL: Auto-immunity to spermatozoa: Effects on sperm penetration of cervical mucus as reflected by post-coital testing. Fertil Steril 41: 609, 1984

56. Fjallbrant B: Interaction between high levels of sperm antibodies, reduced penetration of cervical mucus by spermatozoa and sterility in men. Acta Obstet Gynecol Scand 47: 102, 1968

57. Jager S, Kremer J, Kuiken J et al: The significance of the Fc part of antispermatozoal antibodies for the shaking phenomenon in the sperm-cervical mucus contact test. Fertil Steril 36: 792, 1981

58. Bronson RA, Cooper GW, Rosenreid DL et al: The effect of IgA1 protease on immunoglobulins bound to the sperm surface and sperm cervical mucus penetrating ability. Fertil Steril 47: 985, 1987

59. Bronson RA, Cooper GW: Effects of sperm-reactive monoclonal antibodies on the cervical mucus penetrating ability of human spermatozoa. Am J Reprod Immunol Microbiol 14: 59, 1987

60. Price RJ, Boettcher B: Presence of complement in cervical mucus and its possible relevance to infertility in women with complement-dependent sperm immobilizing antibodies. Fertil Steril 31: 61, 1979

61. Ishahakia MA: Characterization of baboon testicular antigens using monoclonal antisperm antibodies. Biol Reprod 39: 889, 1988

62. Dym M: The fine structure of the monkey (Macaca) sertoli cell and its role in maintaining the blood-testis barrier. Anat Rec 175: 639, 1973

63. Tung KSK, Yule TD, Mahi-Brown CA et al: Distribution of histopathotogy and Ia positive cells in actively induced and passively transferred experimental autoimmune orchitis. J Immunol 138: 752, 1987

64. Mahi-Brown CA, Yule TD, Tung KSK: Evidence for active immunological regulation in prevention of testicular autoimmune disease independent of the blood-testis barrier. Am J Reprod Immunol 16: 165, 1988

65. James K, Hargreave TB: Immunosuppression by seminal plasma and its possible clinical significance. Immunol Today 5: 357, 1984

66. Lord EK, Senabaugh GF, Stites DP: Immunosuppressive activity of human seminal plasma. Part I. Inhibition of in vitro lymphocyte activation. J Immunol 118: 1706, 1977

67. Quayle AJ, Kelly RW, Hargreave TB et al: Immunosuppression by seminal prostaglandins. Clin Exp Immunol 75: 387, 1989

68. Williams-Ashman HG, Lockwood DH: Role of polyamines in reproductive physiology and sex hormone action. Ann NY Acad Sci 171: 882, 1970

69. Mukherjee DC, Agrawal AK, Manjunath I et al: Suppression of epididymal sperm antigenicity in the rabbit by uteroglobulin and transglutaminase. Science 219: 989, 1983

70. Witkin SS, Richards JM, Bangiovanni M et al: An IgG Fc binding protein in seminal fluid. Am J Reprod Immunol 3: 23, 1983

71. Hertenbach U, Shearer GM: Germ cell induced immune suppression in mice: Effect of inoculation of syngeneic spermatozoa on cell-mediated immune responses. J Exp Med 155: 1719, 1982

72. Allen RD, Roberts TK: Role of spermine in the cytotoxic effects of seminal plasma. Am J Reprod Immunol Microbiol 13: 4, 1987

73. Szymaniec S, Quayle AJ, Hargreave TB et al: Human seminal plasma suppresses lymphocyte responses in vitro in serum free medium. J Reprod Immunol 12: 191, 1987

74. Peterson BH, Lammel CJ, Stites DP et al: Human seminal plasma inhibition of complement. J Lab Clin Med 96: 582, 1980

75. Menge AC, Peegel H: Antibody activities of serum and uterine fluid samples from rabbits isoimmunized against sperm factors. Arch Androl 4: 171, 1980

76. Menge AC, Burkons DM, Friedlander GE: Occurrence of embryonic mortality in rabbits iso immunized against semen. Int J Fertil 17: 93, 1972

77. Menge AC, Naz RK: Immunologic reactions involving sperm cells and preimplantation embryos. Am J Reprod Immunol Microbiol 18: 17, 1988

78. Anderson DJ, Johnson PM, Alexander NJ et al: Monoclonal antibodies to human trophoblast and sperm antigens. J Reprod Immunol 10: 231, 1987

79. Gaunt SJ: Spreading of a sperm surface antigen within the plasma membrane of the egg after fertilization in the rat. J Embryol Exp Morphol 75: 259, 1985

80. Hamilton MS: Maternal immune response to oncofetal antigens. J Reprod Immunol 5: 249, 1983

81. Witkin SS, Chaudry A: Circulating interferon in women sensitized to sperm: New mechanisms of infertility. Fertil Steril 52: 867, 1989

82. Jones WR: Immunologic infertility: Fact or fiction? Fertil Steril 33: 577, 1980

83. Margalioth EJ, Sauter E, Bronson RA et al: Intrauterine insemination as treatment for antisperm antibodies in the female. Fertil Steril 50: 441, 1988

84. Anderson DJ, Hill JA: Cell mediated immunity in infertility. Am J Reprod Immunol 17: 22, 1988

85. Kamat BR, Isaacson PG: The immunocytochemical distribution of leukocytic subpopulation in human endometrium. Am J Pathol 127: 66, 1987

86. Bulmer JM, Sunderland CA: Immunohistological characterization of lymphoid cell populations in the early human placental bed. Immunology 52: 349, 1984

87. Xu C, Hill JA, Anderson DJ: Identification of T lymphocyte subpopulations in normal and abnormal human endometrial biopsies. Society for Gynecologic Investigation, Atlanta, Georgia, March 18–21, 1987

88. Hill JA, Cohen J, Anderson DJ: The effects of lymphokines and monokines human sperm fertilizing ability in the hamster egg penetration test. Am J Obstet Gynecol 160: 1154, 1989

89. Hill JA, Haimovici F, Anderson DJ: Products of activated lymphocytes and macrophages inhibit mouse embryo development in vitro. J Immunol 139: 2250, 1987

90. Mahi-Brown CA, Yanagimachi R, Hoffman JC et al: Fertility control in the bitch by active immunization with porcine zona pellucida: Use of different adjuvants and patterns of estradiol and progesterone levels in estrous cycles. Biol Reprod 32: 761, 1985

91. Dunbar BS, Lo C, Powell LJ et al: Use of synthetic peptide adjuvant for the immunization of baboons with denatured and deglycosylated pig zona pellucida glycoproteins. Fertil Steril 52: 31 l, 1989

92. East IJ, Mattison DR, Dean J: Monoclonal antibodies to the major protein of the murine zona pellucida: Effects on fertilization and early development. Dev Biol 104: 49, 1984

93. Shivers CA, Dunbar BS: Autoantibodies to zona pellucida: A possible cause for infertility in women. Science 197: 1082, 1977

94. Sacco AG, Moghissi KS: Antizona pellucida activity in human sera. Fertil Steril 31: 503, 1979

94. Karuchi H, Wakimoto H, Sakumoto T et al: Fertil Steril 41:901, 1984

95. Nishimoto T, Mori T, Yamata F et al: Autoantibodies to zona pellucida in infertile and aged women. Fertil Steril 34: 552, 1980

96. Kamada M, Hasehe H, Irahara M et al: Detection of antizona pellucida activities in human sera by the passive hemagglutination reaction. Fertil Steril 41: 901, 1984

96. Dakhno FU, Hjort T, Grischenko UI: J Reprod Immunol 2:281, 1980

97. Dunbar B: Ovarian antigens and infertility. Am J Reprod Immunol 21: 28, 1989

98. Tung KSK: Human sperm antigens and antisperm antibodies, Part 1. Studies on vasectomy patients. Clin Exp Immunol 20: 93, 1975

99. Alexander NJ, Free MJ, Paulsen CA et al: A comparison of blood chemistry, reproductive hormones and the development of antisperm antibodies after vasectomy in men. J Androl 1:40. 1980

100. Alexander NJ, Clarkson TB, Fulgham DL: Circulating immune complexes and antisperm antibodies in vasectomized and vasovasotomized macaques. Ann NY Acad Sci 438: 5011, 1984

101. Lobatto S, Daha MR, Veerman AA et al: Clearance of soluable aggregates of immunoglobulin G in healthy volunteers and chimpanzees. Clin Exp Immunol 68: 133, 1987

102. Alexander NJ: Vasectomy: Long-term effects in the rhesus monkey. J Reprod Fertil 31: 399, 1972

103. Marsh LD, Alexander NJ: Vasectomy: Effects on the efferent ducts in Macaca mulatta. Am J Pathol 107: 310, 1982

104. Alexander NJ, Fulgham DL, Plunkett ER et al: Antisperm antibodies and circulating immune complexes of vasectomized men with and without coronary events. Am J Reprod Immunol Microbiol 12: 38, 1986

105. Alexander NJ, Clarkson TB: Vasectomy increases the severity of diet-induced athero-sclerosis in Macaca fasicularis. Science 201: 538, 1978

106. Goldacre MJ, Holford TR, Vessey MP: Cardiovascular disease and vasectomy. N Engl J Med 308: 805, 1983

107. Massey FJ et al: Vasectomy and health: Results from a large cohort study. JAMA 252: 1023, 1984

108. Chi I-C, Ko UR, Wilkens LR et al: Vasectomy and non-fatal acute myocardial infarction: A hospital-based case control study in Seoul, Korea. Int J Epidemiol 19: 32, 1990

109. Beer AE, Neaves WB: Antigenic status of semen from the viewpoints of the female and male. Fertil Steril 29: 3, 1978

110. Vander Merwe JP, Kruger TF, Windt ML et al: Treatment of male sperm autoimmunity by using the gamete intrafallopian transfer procedure with washed spermatozoa. Fertil Steril 53: 682, 1990

111. Shulman S: Treatment of immune male infertility with methyl prednisolone. Lancet 2: 1243, 1976

111. Hendry W et al: Fertil Steril 36:351, 1981

112. Shulman JF, Shulman S: Methylprednisolone treatment of immunologic infertility in the male. Fertil Steril 38: 591, 1982

112. Hargreave T, Elton RA: Fertil Steril 38:586, 1982

113. Hendry WF, Treehuba K, Hughes L et al: Cyclic prednisolone therapy for male infertility associated with auto-antibodies to spermatozoa. Fertil Steril 45: 249, 1986

114. Alexander NJ, Sampson JH, Fulgham DL: Pregnancy rates in patients treated for antisperm antibodies with prednisone. Int J Fertil 28: 63, 1983

115. Ayvaliotis B, Bronson RA, Cooper GW, Rosenreid D: Conception rates in couples where auto-immunity to sperm is detected. Fertil Steril 43: 739, 1985

116. DeAlmeida M, Jouannet P: Dexamethasone therapy in infertile men with auto-antibodies: Immunological and sperm follow-up. Clin Exp Immunol 44: 507, 1981

117. Haas GG Jr, Manganiello P: A double blind, placebo-controlled study of the use methylprednisolone in infertile men with sperm-associated immunoglobulins. Fertil Steril 47: 295, 1987

118. Haas GG: Immunological infertility. Obstet Gynecol Clin North Am 14: 1069, 1987

119. Kemmenn E, Bohrer M, Sheldon R et al: Active ovulation management increases the monthly probablity of pregnancy occurrence in ovulatory women who receive intrauterine insemination. Fertil Steril 48: 916, 1987

120. Dodson WC, Whitesides DB, Hughes CL et al: Superovulation with intrauterine insemination in the treatment of infertility: A possible alternative to gamete intrafallopian transfer and in vitro fertilization. Fertil Steril 48: 441, 1987

121. Yovich JL, Stanger JD, Day D et al: In vitro fertilization of oocytes from women with serum antisperm antibodies. Lancet 1: 369, 1984

122. Mandelbaum SL, Diamond MP, DeCherney AH: Relationship of antisperm antibodies to oocyte fertilization in vitro fertilization-embryonic transfer. Fertil Steril 47: 644, 1987

123. Clarke GN, McBain JC, Lopata A et al: In vitro fertilization. results for women with sperm antibodies in plasma and follicular fluid. Am J Reprod Immunol Microbiol 8: 130, 1985

124. Vasquez-Levin M, Kaplan P, Guzman I et al: The effect of female antisperm antibodies on in vitro fertilization, early embryonic development and pregnancy outcome. Fertil Steril 56: 84, 1991

125. Bronson RA: Immunity in sperm and in vitro fertilization. J In Vitro Fert Embryo Transfer 4:195. 1987

126. Clarke GN, Lopata A, McBain JC et al: Effect of sperm antibodies in males in human in vitro fertilization (IVF). Am J Reprod Immunol 17: 65, 1988

127. DeAlmeida M, Gazagne I, Jeulin C et al: In vitro processing of sperm with auto-antibodies and in vitro fertilization results. Hum Reprod 4: 49, 1989

128. Saling PM, Irons G, Waibel R: Mouse sperm antigens that participate in fertilization, Part I. Inhibition of sperm fusion with egg plasma membrane using monoclonal antibodies. Biol Reprod 33: 515, 1985

129. Saling PM, Lakoski HA: Inhibition of sperm penetration through zona-pellucida using monoclonal antibodies. Biol Reprod 33:515. 1985

130. Eider KT, Wick KL, Edward RG: Seminal plasma antisperm antibodies and IVF: The effect of semen sample collection into 50% serum. Hum Reprod 5: 170, 1990

131. Hamilton F, Gutlay-Yeo AL, Meldrum DR: Normal fertilization in men with high antibody sperm binding by the addition of sufficient unbound sperm in vitro. J In Vitro Fert Embryo Transfer 6: 342, 1989

132. Cohen J, Malter H, Weight G et al: Partial zona dissection of human oocytes when failure of zona pellucida penetration is anticipated. Hum Reprod 4: 435, 1989

133. Ng SC, Bongso TA, Sathananthan H et al: Micromanipulation: Its relevance to human in vitro fertilization. Fertil Steril 53: 203, 1990

134. Kola I, Lacham O, Jansen RPS et al: Chromosomal analysis of human oocytes fertilized by microinjection of spermatozoa into the perivitelline space. Hum Reprod 5: 575, 1990

135. Martin R: Analysis of human sperm chromosome complements. In Bavister BD, Cummins J, Roldan ERS (eds): Fertilization in Mammals, pp 365–372. Serono Symposia, USA, Norwell, MA, 1990

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