Antibody-Mediated Causes of Male Infertility

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.

Sperm surface antigens and the prospects for contraceptive vaccine development

It has been estimated that 500 million couples world-wide have no access to contraception and that approximately 20% of births between 1995 and 2000 will be unwanted. Such statistics have important implications for the rate of world population growth and the possibility of maintaining a sustainable population. Although political change and the empowerment of women across the world will help address these issues, it will also be important to increase the availability of contraceptives; not only the modalities that are in current use, but also novel methods that will satisfy needs that are presently unfulfilled. One such alternative could be a vaccine targeting the human spermatozoon.

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.

Predictive parameters for microsurgical reconstruction

Microsurgical techniques have made vasectomy reversal a realistic option for the restoration of fertility in a man who has previously undergone vasectomy. Factors that can affect the success of these procedures may become known preoperatively and intraoperatively; this article reviews each of those factors.

Quantification of C3 and C4 in infertile men with antisperm antibody in their seminal plasma

PROBLEM

Previous studies showed that some infertilities are caused by antisperm antibodies (ASAs). It was shown that some major complement (C) components are present in seminal fluid. Due to the role of C in the pathogenesis of ASAs, the existence and amount of two key C components (C3 and C4) were investigated in seminal plasma (SP).

METHOD OF STUDY

Single radial immunodiffusion assay and a sandwich-type enzyme-linked immunosorbent assay (ELISA) were used for C3 and/or C4 quantification, respectively, in serum and SP, and the tray agglutination test was used for ASA detection in 12 fertile and 53 infertile men (18 ASA-positive [ASA+] and 35 ASA-negative [ASA-] men).

RESULTS

Of the 18 ASA + infertile men, 61.11% had positive C3, whereas 27.77% showed positive C4 levels. ASA + infertile men showed significant differences in seminal plasma C3 mean values compared with ASA- infertile (P < 0.01) and fertile (P < 0.05) men, but the seminal plasma C4 values only showed differences compared with ASA- infertile men (P < 0.05). No significant differences were observed in serum C3 and/or C4 levels of ASA+ infertile men compared with other groups. No significant correlation was found between ASA titer and C3 and C4 levels in SP. A significant correlation existed between SP and serum C3 levels of ASA+ (r = 0.522, P < 0.01) and ASA- (r = 0.451, P < 0.01) infertile men, but no correlation was observed between C4 levels.

CONCLUSIONS

In the presence of ASAs, the C system has no definitive activity in blood serum or outside the male genital tract. In SP, and in association with ASAs, C has no lytic activity by the classical pathway. The excess of C3 in SP of ASA+ infertile men may participate in other C-mediated activities in the male reproductive tract.

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.

Detection of antibodies toward epididymal sperm antigens--an obligatory step in evaluation of human immunologic infertility?

PROBLEM

To test the relative impact of epididymal versus ejaculated sperm in immunologic infertility.

METHOD

Human antibody binding to epididymal and ejaculated spermatozoa was compared by flow cytometry (FCM) since it allows quantitative analysis of viable sperm while ignoring nonsperm cells. To select sera for FCM, GAT, TAT, and ELISA were applied on 145 sera from fertile men, idiopathically infertile and varicocele patients.

RESULTS

All GAT/TAT-positive infertile patients, a representative group of varicocele patients and the fertile control, were assessed by FCM. Higher reactivity toward epididymal sperm revealed 18/22 sera while only four out of them bound to ejaculated sperm stronger than the control. All varicocele sera were positive against epididymal while negative against ejaculated spermatozoa.

CONCLUSIONS

Epididymal sperm antigens may play a predominant role in some cases of immunologic infertility. Such patients might not be adequately diagnosed and respectively treated due to the limitations of diagnostic procedures applying only ejaculated spermatozoa.

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.

Late postoperative results in males treated for testicular torsion during childhood

Successful preservation of a testis that has undergone torsion is directly related to the duration and degree of torsion. From 1979 to 1991, 75 cases of testicular torsion were treated. Eleven orchiectomies were performed; operative detorsion was done in the other 64 cases, with concurrent orchiopexy of both testicles. Twenty-five patients were reexamined 1 to 12 years after the surgery. Age of torsion, duration of symptoms, and operative findings were reevaluated. Testicular volume was determined using Prader's orchidometer, a pachymeter, and ultrasonography. In four postpubertal patients, semen analysis was performed. According to clinical data, results of testicular atrophy correlated with duration of symptoms and operative findings. In all cases of surgical detorsion in which torsion lasted more than 24 hours and viability of the testis was questionable, subsequent atrophy was the rule.

Acute experimental unilateral orchitis in the rabbit and its effect on fertility

We examined the nature of contralateral damage following unilateral orchitis to see if an immunologically mediated mechanism was present. Experimentally induced orchitis in 18 white New Zealand rabbits were examined and compared to 20 in the control groups. Serum antisperm antibody presence and bilateral testicular biopsies (Johansen biopsy score, mean seminiferous tubule diameter) were examined and pregnancy rates were noted. Acute orchitis seemed to be a causative factor in production of antisperm antibody and the presence of antisperm antibody caused histologic changes in contralateral testicles and therefore impaired fertility.

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.

Treatment of male sperm autoimmunity by using the gamete intrafallopian transfer procedure with washed spermatozoa

Sixteen couples were diagnosed as having immunological infertility. To detect sperm-bound immunoglobulin (Ig), i.e., IgA, IgG, and IgM antibodies, the direct immunobead test (IBT) was used. In each individual patient, the direct IBT was greater than or equal to 70% positive for either IgA or IgG or both. The indirect IBT was positive for IgA and IgG antibodies in the serum of all the patients. Semen was collected in 15 mL medium (Ham's F10 [Gibco, Grand Island, NY] + 10% whole blood serum) and prepared with the wash and swim-up method. Patients in the study group were treated for their immunological infertility problem by performing the gamete intrafallopian transfer (GIFT) procedure. An ongoing pregnancy was achieved in 7 of the 16 (43%) couples treated with the GIFT procedure with an ongoing pregnancy rate of 24.1% (7 of 29) per cycle. The GIFT procedure appears to be an effective and safe way of treating male immunological infertility.

Effect of rapid dilution of semen on sperm-bound autoantibodies

The effect of rapid dilution of autoantibody-positive semen on sperm-bound antibodies was studied in 12 male patients (0-100% IgA and 10-100% IgG). The direct immunobead test (IBT) and the sperm cervical mucus contact (SCMC) test were used to detect sperm-bound antibodies on spermatozoa before and after rapid dilution and swim up in HAM F-10 + 10% human blood serum. All patients tested had normal semen parameters. Sperm-bound antibodies detected after swim-up of semen samples ejaculated into 15 ml HAM F-10 + 10% serum (diluted) did not differ significantly from undiluted samples. Most values were lower (IBT and SCMC) but were not statistically significant. Sperm motility, forward progression, and morphology were statistically improved. Pregnancies resulting from washed semen (diluted) in combination with artificial insemination (AIH) or gamete intrafallopian tube transfer (GIFT) took place in spite of antibodies still present on the sperm membrane and can probably be attributed to improved semen quality, minimizing of ovum-sperm distance, and cervical mucus elimination.