In vitro immune absorption of antisperm antibodies with immunobead-rise, immunomagnetic, and immunocolumn separation techniques

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.

Sex difference in anti-sperm antibodies

Background

Some diseases have sex differences. There have been no reports on the relationship between anti‐sperm antibodies (ASA) and sex differences.

Methods

ASA are detected by sperm‐immobilization test using patients' sera in women. In men, the ASA testing is generally performed by direct‐immunobead test.

Main findings

Sperm‐immobilizing antibodies in women inhibit sperm migration in their genital tract and exert inhibitory effects on fertilization. ASA bound to sperm surface in men also show inhibitory effect on sperm passage through cervical mucus. The fertilization rate of IVF significantly decreased when sperm were coated with higher numbers of ASA. For women with the antibodies, it is important to assess individual patients' SI₅₀ titers. In patients with continuously high SI₅₀ titers, pregnancy can be obtained only by IVF. For men with abnormal fertilizing ability by ASA, it is necessary to select intracytoplasmic sperm injection. Production of sperm‐immobilizing antibodies is likely to occur in women with particular HLA after exposure to sperm. The risk factors for ASA production in men are still controversial.

Conclusion

Attention to sex differences in specimens, test methods and the diagnosis of ASA should be paid. For patients with ASA, treatment strategies have been established by considering sex difference for each.

Utility of magnetic cell separation as a molecular sperm preparation technique

Assisted reproductive techniques (ARTs) have become the treatment of choice in many cases of infertility; however, the current success rates of these procedures remain suboptimal. Programmed cell death (apoptosis) most likely contributes to failed ART and to the decrease in sperm quality after cryopreservation. There is a likelihood that some sperm selected for ART will display features of apoptosis despite their normal appearance, which may be partially responsible for the low fertilization and implantation rates seen with ART. One of the features of apoptosis is the externalization of phosphatidylserine (PS) residues, which are normally present on the inner leaflet of the sperm plasma membrane. Colloidal superparamagnetic microbeads ( approximately 50 nm in diameter) conjugated with annexin V bind to PS and are used to separate dead and apoptotic spermatozoa by magnetic-activated cell sorting (MACS). Cells with externalized PS will bind to these microbeads, whereas nonapoptotic cells with intact membranes do not bind and could be used during ARTs. We have conducted a series of experiments to investigate whether the MACS technology could be used to improve ART outcomes. Our results clearly indicate that integrating MACS as a part of sperm preparation techniques will improve semen quality and cryosurvival rates by eliminating apoptotic sperm. Nonapoptotic spermatozoa prepared by MACS display higher quality in terms of routine sperm parameters and apoptosis markers. The higher sperm quality is represented by an increased oocyte penetration potential and cryosurvival rates. Thus, the selection of nonapoptotic spermatozoa by MACS should be considered to enhance ART success rates.

A prospective clinical trial investigating the efficacy of a method of preparing subpopulations of antibody-free spermatozoa from the ejaculates of antibody-positive patients

Couples undergoing in vitro fertilization treatment (IVF) were invited to take part in a controlled prospective clinical trial. The aim was to determine the effect on the fertilization rate of a technique devised to obtain an antibody-free preparation of spermatozoa from an antibody-positive ejaculate. Oocytes collected during IVF were allocated into one of two groups, ensuring that quality and maturity were comparable in each. One group, the control, was inseminated with Percoll-processed spermatozoa. The experimental group was inseminated with identical numbers of Percoll-processed spermatozoa which had been treated to obtain an antibody-free preparation. The treatment was found to have no beneficial effect on the fertilization rate at IVF. Laboratory studies were also performed on the ejaculates of antibody-positive volunteers to determine whether this treatment led to any effects, whether beneficial or detrimental, on sperm function. Membrane integrity was found to be unaffected, as was the percentage of spermatozoa undergoing the spontaneous acrosome reaction following overnight incubation. The percentage of spermatozoa undergoing the ionophore-induced acrosome reaction following treatment, however, was higher than that of the controls. The results of sperm-zona pellucida binding studies were equivocal. The findings indicated that the treatment procedure could not be justified for use in IVF, but may be beneficial for intrauterine insemination.

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.

Sperm-immunobead binding decreases with in vitro incubation

OBJECTIVE

To characterize the stability of the sperm-immunobead association over time.

DESIGN

Prospective evaluation of sperm-immunobead binding, using direct and indirect assays.

SETTING

Male Infertility Clinic, University of California, Davis, Davis, California.

PATIENTS

Eleven men with sperm surface antibodies and 25 men with serum antisperm antibodies volunteered.

MAIN OUTCOME MEASURES

Repeated assessment of sperm-immunobead binding over time.

RESULTS

Serum immunoglobulin (Ig)G decreased a mean of 42.6% over 30 minutes, and serum IgA decreased a mean of 22.7% over 30 minutes. Semen-derived IgG binding fell a mean of 59.9% and semen-derived IgA fell a mean of 27.0% over 25 to 40 minutes.

CONCLUSIONS

Sperm-immunobead coincubation results in a decrease in the number of sperm bound to immunobeads.

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.

Treatment of antibody-associated sperm with media containing high serum content: a prospective trial of fertility involving men with high antisperm antibodies following intrauterine insemination

PROBLEM

Antisperm antibodies (ASAs) associated with the sperm surface can significantly influence oocyte fertilization. We initiated a prospective trial comparing the effect of serum-medium dilution on ASA binding and/or distribution following ejaculation and on subsequent pregnancy rates following intrauterine insemination (IUI).

METHOD

Infertile couples (N = 16) were entered into this prospective randomized protocol where the husband's sperm was at least 50% positive for both IgA and IgG ASAs using the immunobead assay. Couples underwent IUI with washed sperm collected during ejaculation into (a) 10 ml of serum medium made up of 50% maternal serum (antibody negative) in Hepes-buffered medium (SM) or (b) in a sterile cup (DRY). For the following cycle, each couple received the alternate sperm treatment. All patients underwent at least two DRY and two SM collections prior to beginning IUI. Sperm from these collections were analyzed by manual semen analysis, computer-aided semen analysis (CASA), and immunobead testing. All sperm preparations for IUI were analyzed by manual analysis and CASA before IUI. Outcome measures were changes in the distribution and amount of sperm antibody binding, sperm motion parameters, and pregnancy rates following IUI. Statistical analysis was performed using Fisher's exact test.

RESULTS

Collection of sperm into SM significantly reduces (P < 0.01) the percentage of antibody-bound sperm (54.8% IgA, 60.0% IgG) versus 83.5% IgA and 87.7% IgG with DRY collection. The distribution or pattern of antibody binding to the sperm also was altered by SM. There was no significant difference between the motility of the sperm following collection with SM or DRY sperm as determined by manual and CASA methods. More importantly, there was no statistically significant difference in the pregnancy rates/treatment cycle following SM (3.1% 32 cycles) or DRY (6.7%, 30 cycles).

CONCLUSION

Our data suggests that SM collection alters immunobead detectable ASA binding. Localization of ASA binding sites suggests that head-bound antibodies are influenced by SM treatment with little effect on tail-bound antibodies. In spite of the significant reduction of ASAs present on the sperm following SM treatment, there was no influence on pregnancy rates.

In vitro sperm capacitation to treat antisperm antibodies bound to the sperm surface

Our objective was to study antisperm antibody bound to the acrosome region during in vitro capacitation and to determine whether acrosome-antibody free sperm can be obtained from previously acrosome-antibody-coated sperm. The spermatozoa from a selected series of 14 patients were tested for sperm antibodies bound to the sperm surface using d-IBT and focusing on the acrosome positivity. The tests were carried out before the incubation and after 3, 6, 9, and 12 h of incubation in Tyrode's solution with 0.5% human serum albumin as the capacitation medium. Tests to evaluate acrosome region, sperm motion parameters, and zonae binding ability were carried out. In this way we were able to evaluate sperm function during capacitation protocol. The patients were 14 subjects selected according to good seminal characteristics, good post-rise sperm parameters, and high percentage of ASA bound to the sperm surface. In all cases the results showed that antisperm antibodies bound to the acrosome region were shed prior to the acrosome reaction. During sperm capacitation in human a modification, migration, or shedding of plasma membrane molecules takes place. The presence of antibodies in such an important area of the sperm head could certainly interfere in the fertilization process. Our data indicate that in vitro capacitation could provide an in vitro therapy capable of eluting antibodies from the acrosome region.

Immunomagnetic separation of antibody-labelled from antibody-free human spermatozoa as a treatment for immunologic infertility. A preliminary report

A method is described where superparamagnetic polymer microspheres coated with monoclonal antibodies are used to isolate antibody-labelled from antibody-free spermatozoa in male autoimmune infertility. Autoimmune sperm samples or antibody-free spermatozoa adsorbed with antisperm-antibodies from sera were incubated with microspheres coated with a specific monoclonal antibody to murine immunoglobulins, after their preincubation with mouse anti-human IgG and IgA. Using a magnet, the microsphere-labelled spermatozoa were separated from the samples. Immunobead binding was performed before and after the treatment in order to detect changes in the percentage of antibody-bound spermatozoa. After the immunomagnetic separation, approximately 50% of the IgA-labelled spermatozoa was isolated while no difference was demonstrated when antisperm antibodies of IgG class were involved. The evaluation of sperm motility and membrane integrity after treatment seemed to indicate that the technique did not have any relevant effect on sperm characteristics. The fact that only a partial success in separation of IgA-bound spermatozoa and no success for IgG-labelled sperm was obtained indicates that the method needs to be improved before its clinical utilization might be postulated.

Evaluation of human sperm-zona pellucida tight binding by presence of monoclonal antibodies to sperm antigens

Characterized WHO monoclonal antibodies (MAbs) to human sperm antigens were evaluated as to whether they inhibited sperm-zona pellucida tight binding as assessed by the hemizona assay (HZA). Of the 26 MAbs tested, only one inhibited zona binding. The whole sperm-specific MAb inhibited zona binding by 70%. The MAb also caused strong agglutination. Two procedures, Sephadex column chromatography and papain digestion, were used to determine whether agglutination or steric hindrance was a factor in the capability of MAb to inhibit zona binding. However, inhibition remained comparable to previous results. The MAb did not prevent capacitation, nor calcium influx and the resulting increase in hyperactivated motility and acrosome reaction. Since its inhibitory influence is not due to agglutination factors, steric hindrance or prevention of normal pre-fertilization maturation, the MAb may be blocking a portion of the zona binding receptor and may be useful in elucidating sperm antigens important to sperm-egg interaction. The approach used in this study allows definition of sperm surface antigens involved in zona pellucida binding.

Normal fertilization in men with high antibody sperm binding by the addition of sufficient unbound sperm in vitro

A high incidence of fertilization failure has been reported in men with over 70% of their sperm bound with isoantibodies. In three men with greater than 80% antisperm antibody binding with IgG and IgA immunoglobulins, a normal rate of fertilization (29/46 oocytes; 63%) was achieved by adding a sufficient number of motile sperm to provide at least 50,000 unbound sperm per oocyte. This method appears to be simpler and more effective than attempting to separate unbound sperm in vitro.