Anti-sperm IgA antibodies against the equatorial segment of the human spermatozoon are associated with impaired sperm penetration and subfertility

OBJECTIVE

To determine the prevalence of antibodies directed against the equatorial segment of the spermatozoon in (a) serum in both sexes in relation to age and fertility status and (b) semen of infertile men with tail-to-tail sperm agglutination in relation to in vitro sperm penetration capacity.

MATERIAL

Serum samples were obtained from 30 neonates, 11 prepubertal children, 30 adolescents, 60 adults aged 20-50 years, and 60 adults over the age of 70. Semen samples were obtained from 62 men with normal sperm counts and sperm morphology but with tail-to-tail agglutination.

METHODS

Sperm antibodies were demonstrated with an immunoperoxidase assay. Sperm penetration capacity was measured with a modified Kremer capillary test.

RESULTS

Serum anti-sperm antibodies were absent in children but appeared in teen-age boy (10%) and in adult men (20%) and women (30%). Lower prevalence of serum anti-sperm antibodies was noted for old individuals of both sexes (6-10%). Among individuals with a history of infertility, a significantly higher frequency of anti-sperm antibody-positive men (P < .001) and (P < .05) was found as compared to fertile controls. Presence of IgA antibodies bound to the equatorial segment of spermatozoa was associated with impaired in vitro sperm penetration capacity. No IgG or IgM anti-sperm antibodies bound to the equatorial segment were demonstrable.

CONCLUSIONS

Seminal IgA antibodies bound to sperm are associated with impaired sperm penetration.

Sharing of human leukocyte antigens in couples with unexplained infertility affects the success of in vitro fertilization and tubal embryo transfer

OBJECTIVE

The purpose was to test further our hypothesis that genes, or genetic defects, linked to the major histocompatibility complex affect reproduction by correlating human leukocyte antigen sharing with the success or failure of in vitro fertilization and tubal embryo transfer in couples having unexplained infertility.

STUDY DESIGN

Seventy-six couples with unexplained infertility who failed superovulation and intrauterine insemination at least three times were typed for human leukocyte antigens and treated by in vitro fertilization and tubal embryo transfer. The results were correlated with the sharing of human leukocyte antigens in the couples.

RESULTS

Thirty-four of the women had successful pregnancies, 36 did not become pregnant, and six became pregnant but aborted shortly thereafter. There was a highly significant excess of human leukocyte antigen sharing in the couples who failed treatment: three of the A, B, DR, and DQ antigens (p = 0.015) or two of the B, DR, and DQ antigens (p = 0.015). No specific human leukocyte antigen alleles were present in excess.

CONCLUSIONS

Genes, or genetic defects, linked to the major histocompatibility complex significantly affect the success of in vitro fertilization and tubal embryo transfer just as they affect the prevalence of recurrent spontaneous abortion, cancer, and congenital anomalies. It appears as if the critical genes, or genetic defects, are located in the B-DR-DQ region of the major histocompatibility complex.

Determination of antisperm antibodies in serum samples by means of enzyme-linked immunosorbent assay--a procedure to be recommended during infertility investigation?

The clinical significance of antispermatozoal antibody (ASA) testing in serum samples with an enzyme-linked immunosorbent (ELISA) technique using a commercially available kit was evaluated in 95 randomly chosen couples under infertility investigation. Results were related to many other parameters of male and female fertility, e.g. outcome of sperm analysis, testing of sperm functional capacity including the crossed in-vitro sperm-cervical mucus penetration test (SCMPT), results of a microbial screening in genital secretions, testing for local IgG- and IgA-class sperm antibodies in semen by means of the mixed antiglobulin reaction (MAR) and the subsequent pregnancy rate in a prospective study. Results of ASA testing did not show any relationship with medical history and results of clinical examination, the semen quality including sperm function tests and seminal cultures, outcome of the crossed SCMPT, and local ASA. All patients with MAR (IgG or IgA) positive ejaculates were ELISA negative in serum samples. No significant difference with regard to circulating ASA (ELISA) was found in couples with and without a subsequent pregnancy. Furthermore there was no significant difference of antibody levels in subfertile female patients, virgins (n = 36), 'normal' pregnant women (n = 39) and prostitutes (n = 40). In summary, the results of this study clearly demonstrate that the use of this method for detection of antisperm antibodies during infertility investigation cannot be recommended.

HLA class I, class II, and class III antigen sharing is not found in couples with unexplained infertility

OBJECTIVE

To find the degree of HLA antigen sharing in couples with infertility of unknown etiology and compare it with that in couples with infertility of known etiology as well as couples with normal fertility.

SUBJECTS

Eleven couples with infertility of unknown etiology, 26 with infertility of known etiology, and 31 fertile couples were tested for HLA class I (A, B, C), class II (DR, MLC), and class III (Bf) antigens and GLO alleles. HLA lymphocytotoxic antibodies and anti-sperm antibodies in both partners were also searched.

RESULTS

Gene frequencies and the number of HLA antigens shared between the two members of the couple were similar in all groups. When "intra-couple" MLC reactivity was measured, no quantitative differences were found in the infertile group with unknown etiology, as compared to the group of known etiology: spouses in couples of either group usually reacted in both ways as expected for unrelated individuals" lymphocytes. Lymphocytotoxic antibody frequency did not differ between the nonfertile groups, and anti-sperm antibodies, found in ten patients in the group of known etiology, were not associated with any HLA antigen. In spite of that, GLO and all the HLA antigen classes described (I, II and III) were analyzed.

CONCLUSIONS

Although the results are negative, these and others' (negative) results concerning couples with infertility of unknown etiology do not disprove that HLA has a role in fertilization, because HLA-related factors still unknown may exist. Exhaustive HLA available marker typing in international cooperative efforts may be needed to reach a significant number of carefully selected couples fully HLA typed to elucidate this problem.

Complement in human reproduction: activation and control

The behaviour of the complement system during human reproduction is now the focus of much scientific attention. The presence of antisperm antibodies in the reproductive tracts of some infertile individuals, and of complement in cervical and ovarian follicular fluid, suggests that complement-mediated damage of spermatozoa is involved in some cases of infertility. Further, deposition of maternal IgG and of complement in the extrafetal tissues indicates that complement activation occurs within the fetoplacental unit. Recently, three complement-regulatory proteins--decay-accelerating factor, membrane cofactor protein and CD59--have been detected on spermatozoa and in the extrafetal tissues. It is likely that these inhibitors are essential for normal reproductive function. This article reviews current understanding of the interaction of the complement system with cells and tissues involved in reproduction, with emphasis on the nature and function of the controlling proteins.

Relationship of sperm antibodies in women and men to human in vitro fertilization, cleavage, and pregnancy rate

PROBLEM

The presence of anti-sperm antibodies (ASA) in female serum has been correlated with decreased fertilization in the in vitro fertilization (IVF) program; however, the impact of each type of ASA (IgG, IgA, IgM) is not known.

METHOD

To clarify the role of each ASA subtype, the immunobead binding technique was used to identify IgG, IgA, and IgM ASA in the female sera and on the spermatozoa from 137 couples undergoing the IVF program.

RESULTS

Couples with ASA on spermatozoa had a lower fertilization rate and lower number of transferred embryos: and IgG was the major immunoglobin involved. Couples with ASA in female sera showed significant decreases in the rates of fertilization, cleavage, and number of transferred embryos only when IgM was detected, but not IgG or IgA. However, the presence of IgA ASA in female sera was only associated with a decrease in pregnancy rate, although the number of transferred embryos was not reduced.

CONCLUSION

These findings suggest that ASA can influence the results of IVF and that the specific effect is dependent upon the subtypes of ASA.

Detecting semen antisperm antibodies in the clinical laboratory

Although antisperm antibodies are associated with infertility, many hospital laboratories do not test for these antibodies. This study included 520 males who were referred for infertility evaluation. Semen samples from all patients were tested for antisperm antibodies by using the mixed antiglobulin reaction and immunobead binding tests. These results were correlated with the findings of semen analyses, postcoital tests, and sperm penetration assays. Eighty-eight men (16.9%) tested positive for IgG, IgA, or IgM antisperm antibodies. More samples tested positive for IgG antibodies by the mixed antiglobulin reaction than by the immunobead test (n = 71 vs n = 42); 57 samples tested IgA positive. Both methods showed good reproducibility (97.6%). Antibody-positive males had a higher incidence of abnormal semen analyses (92% vs 74%) and other immune-related fertility test results (94.2% vs 38.4%). The presence of antisperm antibodies correlates with other abnormal semen parameters. Testing for these antibodies should be included in an infertility evaluation and could be readily implemented in a clinical laboratory.

Intrauterine insemination with husband's sperm: comparison of pregnancy rates in couples with cervical factor, male factor, immunological factor and idiopathic infertility

Intrauterine insemination with husband's sperm (IUI) is offered to couples with infertility due to various causes although there is no general agreement on which of these causes should be so treated. In this report 77 couples were diagnosed as having either cervical factor, male factor, immunological factor or unexplained infertility. Insemination was performed 24-32 hours after a rapid rise in the serum LH level. Two of 16 pregnancies which resulted miscarried, 1 was ectopic and the remainder were full term. Eleven occurred in the cervical factor group, 3 in the immunological factor and only 1 in each of the male factor and unexplained infertility groups. The differences in the number of pregnancies between the cervical factor and male and unexplained infertility groups are significant but not between the groups with cervical and immunological factors. The majority of pregnancies (81%) were achieved in the first 4 cycles. Patients with the cervical factor as the cause of their subfertility are likely to benefit from the IUI with their husband's sperm. The small number of patients with the immunological factor in this study does not allow for a conclusion. In our experience the male factor and unexplained infertility patients are unlikely to benefit from intrauterine insemination with husband's sperm.

Frequency and predictive value of antisperm antibodies among infertile couples

Although sperm-associated antibody could impair fertility through various mechanisms, the results of follow-up studies do not uniformly confirm that pregnancy rates are lower when one of the infertile partners demonstrates antibody to spermatozoa. We conducted a prospective double-blind cohort comparative analysis in which antibody assay results were not available to physicians or patients for clinical management. The diagnostic protocol included mid-luteal progesterone, semen analysis, hysterosalpingogram and laparoscopy. The serum of each partner was assayed by immunobead testing, tray agglutination testing and a gelatin agglutination test. Data on relevant clinical characteristics and events during follow-up were collected prospectively. Among 471 couples in whom both partners were evaluated, 42 (8.9%) tested positive for anti-sperm antibodies by one or more assays, including 38 (8.1%) male partners and 6 (1.3%) female partners. The number of conceptions was 118/429 (27.5%) in antibody negative couples, 9/38 (23.7%) in male partner-positive couples and 1/6 (16.7%) in female partner-positive couples. With proportional hazards analysis, antibody status in either partner was not a significant independent predictor of time to pregnancy.

Immunologic infertility: a basic review

Antisperm antibodies interfere with the human reproductive events and once they have been produced, antisperm antibodies bind to the spermatic surface and affect both the transport of spermatozoa and the interactions between the gametes. The formation of antisperm antibodies has still not been completely explained and the antigen map of the spermatic surface has not been yet established. The antibody levels in the serum generally do not reflect the immunoglobulin present in the secretions of reproductive tract and in the immunologic screening of the infertile couple we need of direct analysis of antisperm antibodies on the spermatic surfaces. We have many diagnostic procedures but actually very few therapeutic options: to improve the last question, a better understanding of the phenomena that lead to fertilization is imperative.

Histocompatibility in in vitro fertilization couples

Major histocompatibility differences between mother and fetus may facilitate implantation and maintenance of pregnancy. Thus, we have investigated the compatibility of HLAs in couples with three successive failed IVF-ET cycles. The study couples (n = 15) shared a statistically greater number of HLAs than IVF couples achieving a viable pregnancy with their first IVF-ET attempt (n = 15) and a control group of 100 fertile couples. No difference between fertile and infertile control couples was observed regarding HLA sharing. Thus, we conclude that some cases of unsuccessful ETs after IVF might be caused by underlying close histocompatibility between partners.

[Comparison of the indirect immunobead test and the sperm immobilization test for detection of antisperm antibody]

The indirect immunobead test (indirect IBT; IgG.IgA) and the sperm immobilization test (SIT) were carried out for 75 infertile patients to detect antisperm antibodies in the sera. The results were as follows. 1) Twenty three cases showed positive results in the IBT, and 14 out of the 23 showed also positive in the SIT. 2) Fifty two cases which had negative results in IBT also had negative results in SIT. 3) IgG-IB attached to sperm were observed in 14 with positive SIT, but no IgA-IB were observed in 4 cases out of the 14. 4) IgG-IB attached to both the sperm head and end-tail in 12 cases out of the 14, but only to the sperm end-tail in the other 2 cases. We therefore concluded that, 1) IBT detected anti-sperm antibodies more readily than SIT. 2) IBT was an alternative to SIT for screening. 3) Sperm immobilization antibodies appeared to be in the IgG class rather than in the IgA class. 4) It appeared that sperm immobilization antibodies might be able to attach to the sperm tail as well as the head.

[Cell-mediated immune reactivity to sperm in disorders of human reproduction]

Besides the pathological anti-sperm humoral immunity, pathological anti-sperm cell-mediated immunity is considered as a crucial facet of the disturbances of human reproduction (male and female infertility, recurrent abortions, endometriosis, late EPH gestosis, fetal hypotrophy). A precise and objective method is designed, based on a one-step agarose Leukocyte Migration Inhibition Factor assay. The migration areas are evaluated by a computer-assisted image analysis system. Optimal concentrations of leukocytes and sperm, as well as technical conditions are described. The Radius Migration Indexes and Area Migration Indexes are computed and expressed as a Migration Index percentage for each patient or control. Preliminary clinical results indicate a highly significant association between leukocyte migration inhibition and cases of "immunopathological" infertility and repeated fetal loss.

Characterization of human sperm antigens and antisperm antibodies in infertile patients

OBJECTIVE

To identify which sperm antigens may elicit the production of functionally important antisperm antibodies.

DESIGN

Immunoblot analysis was performed on 69 serum and 9 seminal plasma samples from infertile patients, using detergent extracts of pooled donor sperm as the antigen source. Serum and seminal plasma had been previously tested by an indirect immunobead binding test (IBT); 61 IBT-positive and 17 IBT-negative samples were included in the study. Proteins recognized by IBT-positive but not IBT-negative samples were most likely to be cell surface antigens, whereas proteins recognized by both IBT-positive and IBT-negative samples were probably intracellular. Antibodies directed toward surface antigens would be most likely to affect fertilization. Characterization of sperm surface proteins on both acrosome-intact and -reacted sperm used labeling of cell surface proteins with an N-hydroxysuccinimide ester of biotin, fractionation of sperm heads and tails, and lectin binding to determine glycosylation.

RESULTS

Specific immunoreactivity (with respect to IBT results) was observed to 35K, 40 to 45K, 57K, 66K, and 88 to 90K MW proteins. Characterization studies identified an 88K MW glycosylated plasma membrane protein, a 66K MW inner acrosomal membrane protein, a 34K MW inner acrosomal membrane protein, and a 35K MW prominent tail protein.

CONCLUSION

Immunological infertility may involve several antigens characterized in this study. Further studies are necessary to determine if antibodies to these specific proteins interfere with sperm function.

Amphiphilic and hydrophilic domains of human sperm membrane antigens recognized by immunoinfertile sera

Selected sera from married couples with immunological infertility were used to identify antigens on hydrophilic and amphiphilic domains of human sperm membrane. Out of eight sera, six recognized proteins from the hydrophilic as well as amphiphilic regions of the sperm membrane. Sera were either reactive to acrosome or to equator and tail of human sperms in indirect immunofluorescence assay.

The clinical significance of antisperm antibodies in infertile couples

Sera from 150 women and 162 men with unexplained infertility were examined using a commercial enzyme-linked immunosorbent assay (ELISA) kit for antisperm antibodies. The results were compared to those of the Friberg agglutination test, the post-coital test, the sperm-cervical mucus contact (SCMC) test and the pregnancy rate. We also tested follicular fluids obtained from 38 women who underwent in-vitro fertilization (IVF). These data were compared with those obtained in serum, post-coital test data and with the later development of the oocyte in IVF. Antibodies in follicular fluid were found only in women with antibodies circulating in serum. The correlation coefficient between these was 0.88 (P < 0.001). There was no correlation between antisperm antibodies in serum found with the ELISA test, and with the agglutination test, the post-coital test or the SCMC test. Neither was there any correlation between antibodies in follicular fluid and the post-coital test, the pregnancy rate or successful IVF.

Immunological factors in infertility

Immune infertility can result from destruction of gametes by antisperm antibodies (ASA) or anti-ovary antibodies, by inhibition of sperm-zona pellucida binding by ASA, or by prevention of embryo cleavage and early development. Condoms, immunosuppressive therapy, sperm processing, and intrauterine insemination have been widely applied, but with controversial results.

[Anti-sperm antibodies in women and men in infertile marriages]

The authors examined the serum of 76 women and 33 men from infertile marriages for the presence of antispermatozoal antibodies. Seropositivity was revealed in 19 women (25%) and in 12 men (36%). In control groups of healthy men and women seropositivity was substantially less frequent. In women the difference was statistically significant, but not in men. The ELISA method which was applied for examination appears to be a useful tool for screening of immunological factors of infertility, in particular in couples who where infertile for prolonged periods and where no unequivocal cause of infertility was found. Only more detailed comprehensive examination can explain immunologically conditioned cases of infertility and lead to selection of an optimal therapeutic strategy.

Identification of human sperm antigens reacting with antisperm antibodies from sera and genital tract secretions

OBJECTIVE

To identify sperm antigens reacting with antisperm antibodies relevant in human infertility.

DESIGN

The reactions of separated sperm antigens with antibodies present in sera and genital tract secretions from infertile and fertile females and males were examined by immunoblotting techniques.

SETTING

The patients were followed in an outpatient setting of a hospital clinic.

PATIENTS

One hundred consecutive infertile males and females, referred for determinations of antisperm antibodies, comprised the study group. Fifty hospital and faculty employees with proven fertility served as a control group.

RESULTS

A high proportion of sera from fertile and infertile humans contained antibodies reacting with at least one sperm antigen. However, two discrete bands of antigenic proteins with molecular weights of 44 and 72 kd reacted significantly more frequently with serum antibodies from infertile females than from fertile females. No apparent correlation could be demonstrated between any particular antigen and serum antibodies from infertile males. Nevertheless, antigenic proteins of 62 kd were identified as the major sperm antigens reacting with antibodies present in seminal plasmas from infertile males.

CONCLUSIONS

The major sperm antigens reacting with systemic antibodies differ from the antigens recognized by local antisperm antibodies. Sperm antigens exhibiting relative molecular weights of 62 kd are major antigens reactive with local antisperm antibodies from infertile humans.

Effects of human antisperm antibodies on development of preimplantation embryos

The effects of antisperm antibodies (ASAs) present in sera of immunoinfertile patients and vasectomized men were investigated on preimplantation embryonic development in mice. Of the nine immunoinfertile sera tested, two were effective in inhibiting blastulation rates of in vitro cultured murine 2-cell embryos (p less than .05 to .002). Similarly, sera from two of the three vasectomized men were capable of affecting early embryonic development in mice (p less than .05 to .002). Specificities of the embryotoxic effects of ASAs were further confirmed by culturing embryos in the presence of affinity-purified monovalent Fab' antibodies isolated from these sera. Fab' antibodies from only one of the two immunoinfertile patients whose sera affected blastulation rates, and from one of the three vasectomized men were effective in influencing blastulation rates of in vitro cultured 2-cell murine embryos (p less than .05 to .001), mainly due to an arrest of development at 2 to 8-cell and morula stages. In the Western blot procedure, none of the immunoinfertile Fab' antibodies recognized any specific band on blots of extracts from murine ova or 2-cell embryos. However, all the immunoinfertile Fab', but not fertile control Fab', specifically recognized a protein band in the M(r) 25 +/- 2 kD region, on the Western blots of extract from murine blastocyst stage embryos. In addition, Fab' from one immunoinfertile serum, which inhibited embryonic development, reacted specifically with a protein band in the lower molecular range (approximate M(r) 12 kD) on Western blot involving exact from blastocysts. Fab' antibodies of sera from vasectomized men did not react with any specific protein band on blots of extracts from murine ova, 2-cell embryo, or blastocyst. These results suggest that ASAs from some immunoinfertile patients and vasectomized men, especially those reacting with 12-kD blastocyst protein, are capable of affecting preimplantation embryonic development in mice, and thus may contribute toward immunologically medicated infertility both at fertilization and postfertilization stages.

In vitro fertilisation in immunological infertility

Fertilisation occurs through a complex and orderly sequence of changes in both the oocyte and the spermatozoon. Although mechanisms have evolved to protect spermatozoa from recognition by the immune system, there is evidence that a breakdown in protection can occur resulting in homologous or heterologous antisperm antibodies which can immobilise or agglutinate spermatozoa leading to infertility. Antisperm antibodies may affect the reproductive process by interfering with sperm survival and motility and sperm transport through cervical mucus. Fertilisation is also affected, and those oocytes that do fertilise go on to develop poorly. Antisperm antibodies appear to inhibit sperm attachment to and penetration of the zona pellucida. Immune recognition of sperm antigens, which are normally present on the surface of the embryo once fertilisation has occurred, may lead to abortion after implantation. Despite the adverse effects of antisperm antibodies on fertilisation and embryo development, acceptable pregnancy rates can be achieved with assisted reproductive techniques using sperm-washing to remove antibody and using a protein source other than female serum. Further study is necessary to understand the mechanism of immunological infertility and to evaluate newer techniques using micromanipulation of gametes to achieve fertilisation.

Sperm antibodies

Anti-sperm antibodies (ASA) occur in 1% to 30% of infertile couples. Mechanisms by which ASA impair fertility include prevention of fertilization by decreasing acrosome reaction and/or zona pellucida binding, and postfertilization effects. Treatment for ASA involves assisted reproductive technologies.

Gonadotropin-releasing hormone neuronal cell lines

Gonadotropin-releasing hormone (GnRH) cell lines were developed by genetically targeted tumorigenesis in transgenic mice. The cell lines designated GT1 cells have a neuronal phenotype, express neuronal but not glial markers and express the GnRH gene at high levels. The GnRH prohormone is processed in the cells to multiple molecular forms including biologically active GnRH and GnRH-associated peptide. Basal secretion of GnRH from the cells is regulated in part by fast Na+ channels necessary for propagated action potentials. In many instances, basal GnRH release is pulsatile with an interpulse frequency similar to that seen in castrated rodents, suggesting that GnRH neurons are the pulse generator and are capable of synchronizing their secretion in vitro. The secretion of GnRH is stimulated by depolarization and by the neurotransmitter norepinephrine. In related studies we have demonstrated that expression of Simian virus 40 T antigen in GnRH neurons of transgenic mice leads to hypothalamic hypogonadism due to the inability of GnRH nerve terminals to organize in the median eminence. These findings support the use of genetically-directed tumorigenesis to establish highly differentiated GnRH neuronal cell lines that are a valuable model to study the cell biology and regulation of the neurons.

Infertility induced in rats by immunization with synthetic peptide segments of a sperm protein

Three peptide segments (YAL-198, YAL-201 and YAL-212) corresponding to the extracellular domain of a human sperm protein designated as YWK-II antigen were synthesized as multiple antigen peptide (MAP). Male and female rats were immunized with the YWK-II-MAPs and fertility determined. In a group of 12 female rats immunized with YAL-198, seven animals were infertile and two animals were subfertile. When immunized with YAL-201 and YAL-212, 4 and 2 animals were infertile, respectively. In a group of 15 males immunized with YAL-198, 2 animals were infertile and 6 were subfertile. Two animals immunized with YAL-201 were subfertile. All control male and female rats immunized with bovine serum albumin and adjuvant were fertile. Sera obtained from infertile rats immunized with YAL-198 contained higher titers of antibodies compared to those obtained from fertile animals. The present study shows that immunization with synthetic peptide segments of a sperm protein can effectively reduce fertility.