Mechanisms of active suppression of the immune response to spermatozoa

Anti-sperm Antibodies as an Increasing Threat to Male Fertility: Immunological Insights, Diagnostic and Therapeutic Strategies

It is a fact that sperm possess antigenic properties. Substantial scientific research suggests that specific antibodies that attach to sperm antigens can induce infertility in both humans and other species. Antisperm antibodies (ASA) represent a significant etiology of infertility in humans, leading to immunoinfertility. The association between ASA and infertility is multifaceted. The observation of sperm agglutination, although not conclusive for the diagnosis of immunological infertility, may suggest the presence of ASA. Nevertheless, ASA may also manifest in the lack of any sperm agglutination. Managing ASA from an andrological perspective depends on the underlying cause and the specific approaches healthcare professionals adopt. The precise etiology of male infertility resulting from ASA remains unclear. Current research has examined the impact of ASA and its prevalence among infertile males to understand the relationship between ASA and changes in semen parameters. However, the findings have been inconclusive. Numerous techniques have been documented for the management of immunoinfertility. This review examines the importance of ASA in the context of infertility, encompassing the postulated mechanisms underlying the development of ASA, the various assays employed for detecting them, and the available treatments.

Reproductive immunology in viviparous mammals: evolutionary paradox of interactions among immune mechanisms and autologous or allogeneic gametes and semiallogeneic foetuses

Literally, reproductive immunology was born in bovine on-farm reproduction where seminal experiments intended for developing methods for embryo transfer in cattle were performed. Actually, these experiments led to two of major concepts and fundamental principles of reproductive immunology using the bovine species as a model for biomedical research, namely the concept of acquired immunological tolerance and the paradox of the semiallogeneic bovine foetus whereby such organism can develop within an immunologically competent host. Peter Medawar, a scientist who together with Frank Macfarlande Burnet shared the 1960 Nobel Prize in physiology or medicine for discovery of acquired immunological tolerance, while studying dizygotic cattle twins, thereby giving birth to reproductive immunology. Also, these findings significantly influenced development of organ transplants and showed that using farm animals as models for studying transplantation immunology had general relevance for mammalian biology and health including those of humans. However, the interest for further research of the fascinating maternal immune influences on pregnancy and perinatal outcomes and of the prevention and treatment of immunologically mediated reproductive disorders in viviparous mammals of veterinary relevance by veterinary immunologists and reproductive clinicians have been very scarce regarding the application of nonspecific immunomodulatory agents for prevention and treatment of subfertility and infertility in pigs and cattle, but still broadening knowledge in this area and hold great potential for improving such therapy in the future. The aim of the current overview is to provide up-to-date information and explaining/translating relevant immunology phenomena into veterinary practice for specialists and scientists/clinicians in reproduction of animals.

Diabetes Mellitus and Infertility: Different Pathophysiological Effects in Type 1 and Type 2 on Sperm Function

Although the prevalence of sub-infertility in diabetic patients in childbearing age is known, the mechanisms by which diabetes mellitus (DM) causes male infertility are not completely explained. This detrimental effect is achieved with a variety of mechanisms that include pre-testicular, testicular, and post-testicular pathogenetic moments and can be different in type 1 diabetes mellitus (DM1) and type 2 diabetes mellitus (DM2) patients because of type of diabetes, duration of disease, and glycemic metabolic compensation. Aim of this study was to evaluate whether diabetic disease can be considered a risk factor for infertility considering the etiopathogenetic differences between DM1 and DM2 on sperm function. We enrolled 38 DM1 patients and 55 DM2 patients with idiopathic infertility history >12 months, and 100 healthy fertile subjects. The following outcomes were evaluated in optical microscopy and flow cytometry: sperm function (by conventional and biofunctional sperm parameters) and signs of urogenital infection/inflammation (by sperm leukocyte concentrations and indices of oxidative stress). Moreover, an andrological evaluation (by didymo-epididymal ultrasound evaluation, serum total testosterone, LH, and FSH measurements) was performed in DM1 and DM2 patients compared to controls. Diabetic patients showed a higher risk of becoming infertile and the pathophysiological mechanisms of damage were different in DM1 and DM2. Conventional sperm parameters of diabetic patients are worse than controls (p < 0.05). The DM2 caused an inflammatory condition with increased oxidative stress resulting in decreased sperm vitality and increased sperm DNA fragmentation. DM1 altered epididymal voiding causing low ejaculate volume and mitochondrial damage resulting in decreased sperm motility. These findings and evidences support the contention that DM could be regarded as cause of male infertility suggesting that the prevention of diabetic disease in DM2 and the follow-up of seminal parameters in DM1 could prevent fertility decline in these categories of patients.

Immune regulation in the male genital tract

Spermatozoa are not produced until puberty, long after the establishment of tolerance to self-antigens. Therefore, sperm-specific antigens are immunogenic in men. Most men, however, do not produce antibodies to their own gametes. Development of mechanisms to prevent or limit autoimmune responses to spermatozoa were essential for preservation of reproductive capacity. Tight junctions between adjacent Sertoli cells, as part of the blood-testis barrier, prevent sperm-immune cell contact. In some portions of the genital tract this barrier is thin or incomplete. Immune mechanisms have evolved to actively suppress the autoimmune response to spermatozoa within the genital tract. Unlike in the circulation where CD(4+) helper T lymphocytes predominate, CD(8+) suppressor/cytotoxic T lymphocytes are the most prominant T cells in the epididymis and vas deferens. In addition, spermatozoa suppress pro-inflammatory lymphocyte immune responses, possibly by inducing production of anti-inflammatory cytokines. Antisperm antibody production is induced in the male genital tract when a local infection or disruption in the genital tract physical barrier leads to an influx of CD(4+) T cells. In response to induction of a productive immune response, two additional mechanisms downregulate humoral immunity within the genital tract. T lymphocytes possessing the gammasigma form of the antigen receptor (gammasigma T cells) are concentrated in the male genital tract and in semen. These cells become activated and proliferate in men with evidence of sperm autoimmunity. Activated gammasigma T cells inhibit production of antibodies by activated B lymphocytes, thereby limiting antisperm antibody production. Heat shock proteins (hsps) are also present in semen in association with infection and antisperm antibody formation. Hsp gene transcription leads to inhibition of transcription of the genes coding for pro-inflammatory cytokines and, conversely, to activation of gammasigma T cells. Activated gammasigma T cells also promote hsp synthesis. The mechanisms to inhibit immunity to sperm may hinder effective immune elimination of microoganisms in the male genital tract.

Immune pathogenesis of asymptomatic chlamydia trachomatis infections in the female genital tract

Chlamydia trachomatis (CT) infections of the female genital tract, although frequently asymptomatic, are a major cause of fallopian-tube occlusion and infertility. Early stage pregnancy loss may also be due to an unsuspected and undetected CT infection. In vitro and in vivo studies have demonstrated that this organism can persist in the female genital tract in a form undetectable by culture. The mechanism of tubal damage as well as the rejection of an embryo may involve an initial immune sensitization to the CT 60 kD heat shock protein (HSP), followed by a reactivation of HSP-sensitized lymphocytes in response to the human HSP and the subsequent release of inflammatory cytokines. The periodic induction of human HSP expression by various microorganisms or by noninfectious mechanisms in the fallopian tubes of women sensitized to the CT HSP may eventually result in tubal scarring and occlusion. Similarly, an immune response to human HSP expression during the early stages of pregnancy may interfere with the immune regulatory mechanisms required for the maintenance of a semiallogeneic embryo.

Screening of an antigen target for immunocontraceptives from cross-reactive antigens between human sperm and Ureaplasma urealyticum

Epidemiologic studies indicated that some infertile men who were infected with Ureaplasma urealyticum displayed positive antisperm antibodies in their serum and/or semen. The purpose of this study was to investigate the possible mechanism of antisperm antibodies production after infection with U. urealyticum and to analyze the relationship between U. urealyticum and infertility. The existence of cross-reactive antigens (61, 50, and 25 kDa) between U. urealyticum and human sperm membrane proteins was confirmed. Among the cross-reactive antigens, the urease complex component UreG of U. urealyticum was determined. By searching the Swiss-Prot protein database, a pentapeptide identity (IERLT) between UreG and human nuclear autoantigenic sperm protein (NASP) was found. Furthermore, using Western blot analysis and enzyme-linked immunosorbent assay, the cross-reaction between the NASP and UreG was verified. Both anti-rUreG antibody and the antiserum against the synthetic peptide NASP393-408 containing the pentapeptide inhibited mouse sperm egg binding and fusion. After immunization by rUreG or the synthetic peptide, 81.2 and 75% female mice became sterile, respectively. The effect on fertility in mice immunized with the synthetic peptide was reversible. These findings proved for the first time that it was feasible to screen antigens for immunocontraceptives from cross-reactive antigens between sperm and microorganisms which induce infertility.

Tissue microcircumstances for leukocytic infiltration into the testis and epididymis in mice

Spermatozoa do not appear in the seminiferous epithelium until puberty, when immune tolerance has already been established. Therefore, they contain various autoimmunogenic materials which are recognized as foreign by the self immune system. However, the testis and epididymis are known as immunologically privileged organs. In particular, the blood-testis barrier (BTB) formed by Sertoli cells and the blood-epididymal barrier formed by epididymal epithelial cells protect autoimmunogeneic spermatozoa from attack by the self immune system. The immune privileged circumstances in the testis and epididymis have been demonstrated by many studies to involve a local transplantation system. We review here the immune privileged status of these organs from the viewpoint of induction of inflammatory cell responses in mice. The testicular interstitium in mice is resistant to vasculitis, lymphangitis, spermatic granuloma and polymorphonuclear cell infiltration: however, the epididymal interstitium is vulnerable to them. Therefore, the testicular tissue outside BTB is also protected from inflammatory cell infiltration, although many resident macrophages are normally present in the testis. In sharp contrast, subcutaneous injection of viable syngeneic testicular germ cells (TGC) alone induces autoimmune orchitis with no involvement of the epididymitis in mice. In the testes of TGC-immunized animals, severe lymphocytic infiltration with aspermatogenesis was seen in spite of no use of adjuvants. Unexpectedly, injections of viable epididymal spermatozoa (ES) did not evoke any autoimmune inflammation in the epididymides. Therefore, the testis rather than the epididymis may easily become an unprivileged organ as to autoimmunity under some special conditions.

Decreased suppression of antibody-dependent cellular cytotoxicity by seminal plasma in unexplained infertility

OBJECTIVE

To determine whether seminal plasma (SP) from unexplained infertile males has different suppressive activity on antibody-dependent cellular cytotoxicity (ADCC) than SP from fertile males or SP from males of couples with known infertility factor.

DESIGN

Comparative clinical/experimental study.

SETTING

In vitro fertilization program in a university hospital and a hospital research laboratory.

PATIENT(S)

A total of 245 SP samples from 174 infertile and 16 fertile couples were compared.

INTERVENTION(S)

SP suppression of ADCC was measured by using human 51chromium-labeled red blood cells (RBC), sensitized with IgG-rabbit-anti-human-RBC as targets and peripheral blood lymphocytes as effector cells.

MAIN OUTCOME MEASURE(S)

Suppressive activity of each sample was determined by calculating 51Cr-release in the presence and absence of SP.

RESULT(S)

When analyzed with respect to sperm number, motility, and morphology, suppressive activities of samples with normal semen analyses (n = 142) were significantly higher (x = 37% +/- 14%) than suppressive activities of abnormal samples (n = 103; x = 32% +/- 13%). There was no strong correlation of suppressive activity to other semen parameters. Within the andrologically normal males, SP from the unexplained infertile couples (n = 15) showed significantly lower suppressive activity (x = 24% +/- 11%) compared with the SP from fertile males (n = 16; x = 35% +/- 13%) and from couples with female infertility factor (n = 65; x = 39% +/- 14%).

CONCLUSION(S)

Loss of suppressive activity is associated with unexplained infertility, even in male patients who previously were considered normal by traditional methods of semen analysis.

Seminal plasma immunoglobulin concentrations in autoimmune male subfertility

The presence of anti-sperm antibodies (ASAs) in seminal plasma is associated with infertility. They have been shown to reduce sperm motility, interfere with cervical mucus penetration and gamete interaction, and have been shown to reduce spontaneous fertilization and pregnancy rates. Although some causes can be determined, in the majority of cases the initial event causing the immune sensitisation and the reasons for the continuing antibody secretion remains unknown. Quantitative determination of total IgG, IgA and IgM within seminal plasma had not been previously reported in patients with and without specific ASAs. Semen samples from 512 men presenting with infertility were analyzed. One hundred and forty-six men (28.5%) had seminal fluid ASAs as determined by the MAR or TAT tests. The total seminal plasma IgG and IgA concentrations were significantly elevated in the ASA-positive groups compared with ASA-negative groups (IgG: 8.83 mg/100 ml vs. 7.15, P = 0.0008; and IgA: 2.88 mg/100 ml vs. 1.64, P = 0.0001). Only 19 samples showed seminal fluid IgM, and there was no difference between the ASA positive or ASA negative samples. The significance of these findings is discussed.

Characterization of anti-sperm antibodies and their coding cDNA sequences by Epstein-Barr virus transformed B cell lines from lymphocytes of infertile women possessing anti-sperm antibodies

Epstein-Barr virus (EBV)-transformed B cell lines that produce human antisperm antibodies were established using peripheral blood lymphocytes (PBLs) from infertile women with sperm immobilizing antibodies in their sera. We obtained three stable cell populations (designated B1, B2, D5) of transformed PBLs originating from three different patients. They produced IgM sperm-reacting antibodies directed against the tail of live, methanol-fixed and NaIO4-treated human spermatozoa. The established antisperm antibodies recognized noncarbohydrate sperm membrane antigens with different specificity and distribution in the male reproductive system. Antisperm antibody-B2 corresponding antigen appears to be specific for the male reproductive system. This antigen is excreted from the epithelial cells of the ductus epididymidis and bound to the spermatozoa in the lumen of the ductus. Antisperm antibodies B1 and D5 corresponding antigens were expressed on the spermatozoa in the seminiferous tubules and were common to the secretions of the ductus epididymidis, prostate and some other somatic organs. The cDNA of the immunoglobulin heavy chain genes were analyzed by reverse transcription polymerase chain reaction (RT-PCR) using RNA extracted from these clones. The immunoglobulin heavy chain cDNA sequences of these antisperm antibodies showed extremely high homology to previously reported immunoglobulin germline DNA sequences, implying that these antisperm antibodies might be natural autoantibodies rather than antibodies stimulated by external antigen.

Expression of human leukocyte antigens in patients with autogenic and allogenic circulating antisperm antibodies

Circulating antisperm antibodies have been shown to have an adverse effect on a couple's ability to achieve fertilization. This study investigated the HLA class II pattern in couples with infertility associated with antisperm antibodies. Forty-nine couples with significant circulating antisperm antibodies confirmed with immunofluorescence technique and 15 control couples had HLA class II-DR, DQ typing. The Terasaki lymphotoxicity test was used. In women with antisperm antibodies, HLA class II haplotypes DR4, DR6, and DQW3 were more common than in the control group. For the men, DR6 and DQ7 were more common in those with antisperm antibodies, than in controls. With sharing of the haplotypes by the couples, DR4, DR6, and DQ7 were more common in couples with antisperm antibodies, but deficient in DQW3. HLA class II-DR4, DR6, and DR7 sharing in couples and deficiency of DQW3 may be associated with circulating antisperm antibody production.

Clinical and biological aspects of male immune infertility: a case-controlled study of 86 cases

A case-control study of clinical, endocrine and seminal characteristics in 86 infertile men and a prospective study of conception rates during 804 follow-up cycles among 75 infertile couples with male immune infertility were performed. Genito-urethral infections or surgery, and palpable epididymal abnormalities were more common among the immunological cases than among the non-immunological infertile controls (n = 180), but sperm concentration, motility and morphology were similar. The spontaneous conception rate in 70 cases was 1.7% per cycle. Treatment by intra-uterine insemination (IUI) resulted in 8.6% pregnancies per cycle, conventional in vitro fertilization (IVF) had a 18.4% success rate per attempt, and two out of three couples treated by intracytoplasmic sperm injection (ICSI) attained pregnancy. Minimal sperm quality required for successful IUI was not lower than that recorded in couples with spontaneous conception. It is concluded that immunological infertility, as diagnosed by a positive mixed antiglobulin reaction (MAR) test, is associated with a low spontaneous conception rate. Techniques of assisted reproduction are useful in the management of couples with infertility resulting from this pathology, but sperm characteristics required for successful IUI are much higher than those needed for successful IVF. A strategy for the logical management of this pathology is proposed.

Sperm immobilization antibodies in infertile male sera decrease the acrosome reaction: a possible mechanism for immunologic infertility

OBJECTIVE

To study the effect of sperm-immobilizing antibodies from male sera on spontaneous and A23187-induced acrosome reactions (AR).

DESIGN

Swim-up spermatozoa obtained from three fertile donors were incubated with 13 sera with sperm-immobilizing antibodies obtained from infertile men and three control sera obtained from healthy fertile males. Sperm acrosomes were examined by staining with pisum sativum agglutinin labeled with fluorescein isothiocyanate (30 micrograms/ml; Sigma Chemical Co., St. Louis. MO) as spontaneous and A23187 (used at a final concentration of 10 microM; Sigma Chemical Co.) induced.

RESULTS

The incidence of spontaneous AR of spermatozoa incubated with antisperm antibody positive male sera (6.2 +/- 0.7) was significantly (P < 0.001) lower than that of spermatozoa incubated with control sera (10.7 +/- 0.5). And the incidence of A23187-induced and -inducible (incidence of induced minus spontaneous) ARs of spermatozoa incubated with sperm antibody-positive male sera (12.4 +/- 1.9 and 6.2 +/- 1.9) was significantly lower (P < 0.001) than that of spermatozoa incubated with control sera (31.0 +/- 0.5 and 20.3 +/- 0.9). Sperm-immobilizing antibody-positive sera decreased spontaneous, A23187-induced, and inducible ARs.

CONCLUSIONS

Sperm-immobilizing antibodies from male sera interfere with fertilization by inhibiting the AR.

Infertility due to antisperm antibodies

Immunoinfertility is an important problem, involving a significant number of infertile couples. Although the presence of antibodies on sperm has better prognostic value than those in serum or seminal plasma, it may not be the sole authentic evidence of immunoinfertility. Infertility from antisperm antibodies is likely only when they bind to a relevant sperm antigen involved in a specific fertility function. The variance in functional deficits seen in immunologic infertility is most likely related to antibodies directed at different sperm antigens or different class, subclass, or isotypes. Antibodies to FA-1 seem to be of significant importance in human immunoinfertility. In approaching couples with infertility, a high index of suspicion for antibodies is necessary to avoid misdiagnosis. In the optimal situation, all semen analyses should be screened for sperm-bound antibodies, but if this is impractical, testing should be performed on high-risk individuals (Table I). In couples in which the man has sperm-bound antibodies, and in whom there is no identifiable female factor, treatment should be instituted. Most treatments for immunoinfertility have been disappointing because of poor results, adverse effects, or high cost. Corticosteroid therapy has shown some promise in published reports (mostly poorly designed studies), but increase in pregnancy rate is modest and adverse effects may be significant. In our opinion, informed consent should be documented prior to institution of corticosteroid therapy, and subjects should be closely monitored. Advanced reproductive technologies offer a higher safety profile, and, with increasing technology, higher pregnancy rates. We recommend progressing from "low-tech" procedures, such as IUI and reserving the higher level procedures, such as IVF and ICSI, for those couples in whom pregnancy does not occur. The highest level reproductive technologies give the best current prospects for pregnancy in patients with this difficult problem but also are invasive and costly. It is hoped that further work in the laboratory will give rise to newer, safer, and less expensive effective treatments in the very near future.

Identification of human seminal plasma components that bind IgG2 variant

Human seminal plasma (hsp) contains soluble proteins capable of binding immunoglobulin (Ig) G. Two novel components with estimated molecular sizes of 90 and 21 kD interact specifically with a variant of IgG2 found in 20% of human sera tested. The common IgG2 present in human sera and other subclasses of IgG did not bind with the hsp components. The present findings shows that the interacting IgG2 is a variant and not the common or prevalent species. The 90-kD component of hsp with IgG2 binding property is probably a nonglycosylated protein, whereas the 21-kD component is a glycosylated protein. The 90- and 21-kD components were detected in 20% of hsp specimens tested. Thus they are not present in the majority of hsp. Since the IgG2 binding components of hsp and the serum IgG2 variant are found in 20% of men and 20% of individuals, respectively, they can be used as genetic markers.

Antisperm antibodies: origin, regulation, and sperm reactivity in human infertility

OBJECTIVE

To follow-up and expand discussion on the action mechanisms of antisperm antibodies in human infertility, the etiology and control of antisperm antibody induction, sperm antigens involved in immunoinfertility, and strategies for therapy.

DESIGN

A review of the recent literature with an emphasis on female immunoinfertility.

RESULTS

The role of antisperm antibodies in clinical infertility continues to be defined. Through assisted reproductive technologies, antisperm antibodies were shown to exert detrimental effects on different prefertilization and possibly postfertilization events. The female reproductive tract is part of the common mucosal immune system and is able to mount effective immune responses against infectious agents, foreign antigens, and, occasionally, sperm cells. Sperm membranes and constituents contain numerous antigenic components foreign to the human body, and yet antisperm antibodies become problematic in few women exposed to semen. Semen and sperm cells contain immunosuppressive factors capable of inhibiting different immune cells. Fertile women apparently produce antisperm antibodies but also possess neutralizing serum anti-idiotypic antibodies that are lacking in virgin and immunoinfertile women.

CONCLUSIONS

Antisperm antibodies can affect adversely human fertility but normally may be controlled by anti-idiotypic antibodies, which along with immunosuppressor factors in semen prevent their induction to a significant degree. This balance between detrimental and "beneficial" immune response to sperm may be shifted toward an antisperm antibody response by stimulatory factors such as infection. Therapies may be devised to stimulate the anti-idiotypic antibody system, to induce immune tolerance to sperm antigens, and to use antigens to adsorb antisperm antibodies from spermatozoa.

The role of antisperm antibodies in infertility

OBJECTIVE

To discuss the role of antisperm antibodies (Ab) in infertility, including proposed mechanisms of antisperm Ab formation, assays for their detection, and treatments for immune-mediated infertility.

DESIGN

Major studies in the published literature and data from The University of Texas Southwestern Medical Center, Division of Reproductive Endocrinology. Reports were reviewed that investigated the development and impact of alloimmunity and autoimmunity to spermatozoa in men and alloimmunity in women and the current methods of treatment for resultant subfertility.

RESULTS

The exposure of spermatozoal antigens to the mucosal and systemic immune systems results in development of immunity to a multiplicity of spermatozoal epitopes. The evaluation of studies that examine the role of antisperm Ab in infertility is complicated by the lack of standardization of antisperm Ab assays and the difficulty in identifying those epitopes for antisperm Ab binding that are responsible for subfertility. Sperm-associated antisperm Ab and antisperm Ab in cervical mucus (CM) reduce sperm mobility and may also impair sperm-ovum interaction. The clinical significance of serum antisperm Ab in both men and women, however, is controversial. Current therapy for antisperm Ab associated infertility is empiric and largely unproven.

CONCLUSIONS

Antisperm Ab on the sperm surface and in CM are implicated in the pathogenesis of a subset of patients with infertility. Further studies that determine the clinically relevant sites of antisperm Ab interaction will aid in directing the treatment of subfertility mediated by antisperm Ab.

Enrichment of gamma delta T lymphocytes in human semen: relation between gamma delta T cell concentration and antisperm antibody status

The presence and relative concentrations of T lymphocytes bearing the alpha beta and gamma delta cell receptor (TCR) in human semen were assessed and related to the occurrence of auto-antibodies to sperm in semen and peripheral blood. Using an immunoperoxidase technique, and monoclonal antibodies to the beta chain and delta chain of the human TCR, both alpha beta and gamma delta T cells were detected in each of 30 semen samples examined. In seven men with antisperm antibodies both on their ejaculated sperm and in their serum, the mean concentrations of gamma delta and alpha beta T cells were 3,560 and 3,230 cells/ml semen, respectively. In seven men with antisperm antibodies in serum only, the concentrations of gamma delta and alpha beta T cells were 860 and 1,280 cells/ml, while in 16 men with no evidence of auto-immunity to sperm there was a mean of 350 gamma delta T cells and 610 alpha beta T cells/ml. In contrast, the concentrations of gamma delta and alpha beta T cells in peripheral blood from these same men were unrelated to antisperm antibody status. The mean ratio of alpha beta to gamma delta T cells in peripheral blood of all subjects was 12. The ratio of alpha beta to gamma delta T cells in semen were 0.9 for men with sperm-bound and serum antisperm antibodies, 1.5 for men with antisperm antibodies in serum only and 1.7 for men lacking these auto-antibodies. These results were confirmed by FACS analysis. Thus, gamma delta T cells in human semen comprise a greatly increased proportion of the total T cell population as compared to the circulation. In addition, the relative and absolute concentration of gamma delta T cells are further elevated in semen from men with evidence of localized auto-immunity to their own sperm. These results suggest that gamma delta T cells may function in immune surveillance in the non-sterile proximal portions of the male genital tract and that replication of T cells bearing the gamma delta TCR accompanies an autoimmune response to sperm.

Antisperm antibodies to sperm surface antigens in women with genital tract infection

Antisperm antibodies to sperm surface antigens in nulligravid women with primary upper genital tract infections were measured by the sperm mixed agglutination reaction assay. As many as 56% of women with a primary episode of pelvic inflammatory disease had antisperm antibodies. In addition, 69% of those women with no history of genital tract infection but with laparoscopic evidence of past pelvic infection had significant levels of circulating antisperm antibodies. Electroimmunoblots of sperm preparations probed with the sera of women who had either known or presumed upper genital tract infection revealed a uniformly recognized 69 kd antigen. In contrast, women with circulating antisperm antibodies before primary upper genital tract infection recognized up to five distinct sperm antigen determinants of 27, 54, 131, 146, and 174 kd. It is a distinct possibility that genital tract infections may lead to immunopotentiation of antisperm antibodies that could affect fertility.

Antisperm antibodies in women undergoing intrauterine insemination

Intrauterine insemination is widely used for the treatment of infertility as a result of cervical or male factors or empirically before in vitro fertilization or gamete intrafallopian transfer. This study was designed to confirm or refute the theoretical concern that intrauterine insemination may induce antisperm antibodies in such women. Serum and cervical mucus were obtained at the first, fourth, and sixth intrauterine inseminations. The serum was screened by the Immunobead test for IgG and IgA. If screening results were positive (greater than 10% binding), antisperm antibodies were titered by the microimmobilization and microagglutination tests. The Immunobead test was performed on the cervical mucus after liquefication with bromelin. Ninety-three patients were followed up prospectively. Of these, 40 completed six intrauterine insemination cycles and the remaining 53 completed four cycles. Low transient antisperm antibody levels were detected in 10.8% of the patients and would not be expected to affect the prognosis for fertility. It is concluded that intrauterine insemination does not induce significant antisperm antibody production in women.

Antisperm antibodies and lymphocyte subsets in semen--not a simple relationship

The significance of white blood cells in the ejaculate remains a matter of controversy. Several authors have suggested that such cells are important in the modulation of an antisperm antibody response, i.e. a predominance of suppressor/cytotoxic to helper/inducer T cells may prevent the development of antisperm antibodies. In order to examine this relationship further we have documented the white blood cell types, with emphasis on the T-lymphocyte populations, in the ejaculates of men from infertile couples with and without antisperm antibodies; the latter group was divided further into two groups--vasovasostomized men and idiopathic men. All seven of the men without antisperm antibodies had a predominance of suppressor/cytotoxic T cells to helper/inducer T cells in the ejaculate. However, only in some of the men with antibodies was there a predominance of T-helper/inducer cells. It is clear that the relationship between antisperm antibodies and seminal leucocytes is therefore not as straightforward as has been proposed.

Relationship between circulating antisperm antibodies in women and autoantibodies on the ejaculated sperm of their partners

The relationship between antibodies on the surface of ejaculated sperm and circulating antibodies in female partners was evaluated. Of 616 couples examined by the immunobead binding test, there was a 12.4% incidence of sperm-surface antibodies in men whose wives had antisperm antibodies in their sera, but only a 6.5% incidence in partners of women who lacked these antibodies (p less than 0.025). Sperm-bound immunoglobulin G and immunoglobulin A both occurred at a significantly higher frequency (p less than 0.05) in partners of women with serum antisperm antibodies. Increased incidence of both immunoglobulin G (p less than 0.01) and immunoglobulin M (p less than 0.005) circulating antisperm antibodies in females were observed when the male partners had antibody-bound sperm. Antibody-coated sperm may activate lymphocytes in the female partners after coitus, thus leading to the production of antisperm antibodies. This may be an additional mechanism that leads to female isoimmunity to sperm and infertility.

Failure of sperm-induced immunosuppression: association with antisperm antibodies in women

The ability of husbands' sperm to inhibit proliferation of their wives' lymphocytes was measured. Seventeen of 27 sperm samples tested (63%) inhibited lymphocytes from responding to Candida antigens. Eleven of the 27 women (41%) had sera that were positive for antisperm antibodies; sperm from only four of their husbands (36%) were immunosuppressive. In contrast, 13 of the 16 women (81%) without antisperm antibodies had partners with suppressive sperm. Lymphocytes from four women with antisperm antibodies were inhibited by sperm from a fertile donor although not inhibited by their husband's sperm, whereas in three other antibody-positive women neither the husbands' nor donors' sperm were inhibitory. Antisperm antibodies in some women may arise as a consequence of a failure of sperm from their male partners to inhibit lymphocyte activation.

Association between recurrent spontaneous abortions and circulating IgG antibodies to sperm tails in women

The isotype and regional specificity of antisperm antibodies in the circulation of women with recurrent spontaneous abortions was examined. There was a statistically significant association (P less than 0.005) between the presence of IgG tail-directed antisperm antibodies and a history of unexplained recurrent spontaneous abortion. These antibodies were detected in 36.4% of 44 women with recurrent abortions and 14.6% of 616 female partners of infertile marriages. In contrast, no differences in IgG sperm head-directed antibodies or in IgA and IgM antisperm antibodies were observed between the two groups. Husbands of women in the miscarriage or infertile groups had similar semen evaluations. Antisperm antibodies may be a marker for defective immunosuppression in women with recurrent miscarriages. Alternatively, exposure of sperm-sensitized pregnant women to sperm may activate the maternal immune system to respond to paternal antigens present on the embryo.

Reduced levels of T suppressor/cytotoxic lymphocytes in semen from vasovasostomized men: relationship to sperm autoantibodies

The regulation of lymphocyte populations in semen and their function remains unknown. Using monoclonal antibodies and immunohistochemical techniques we compared the levels of mononuclear cells in ejaculates obtained from 14 men with intact vas deferens and 13 men who had undergone both a vasectomy and a microsurgical vasovasostomy. The presence of antisperm antibodies was also assessed by the immunobead binding assay. Semen from both groups contained about 10(3) T and B lymphocytes and monocytes. In men with intact vasa, T suppressor/cytotoxic cells predominated. In contrast, in vasovasostomized men the levels of T suppressor/cytotoxic cells were significantly reduced (P less than 0.005) and T helper/inducer cells predominated in their semen. Concentrations of seminal T helper/inducer lymphocytes, B lymphocytes and monocytes were similar in both groups. Antisperm antibodies were detected on sperm, in seminal fluid and/or in serum of all the vasovasovasostomy patients but in none of the controls, T suppressor/cytotoxic cells may limit the immune response to sperm within the male reproductive tract. Chronic obstruction resulting in damage to the integrity of the excurrent ducts may induce alterations in T cell regulation leading to a decrease in T suppressor/cytotoxic cells and create conditions permissive for the formation of autoantibodies to sperm-specific antigens.