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

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.

Immunology of the Testis and Male Reproductive Tract

A large body of evidence points to the existence of a close, dynamic relationship between the immune system and the male reproductive tract, which has important implications for our understanding of both systems. The testis and the male reproductive tract provide an environment that protects the otherwise highly immunogenic spermatogenic cells and sperm from immunological attack. At the same time, secretions of the testis, including androgens, influence the development and mature functions of the immune system. Activation of the immune system has negative effects on both androgen and sperm production, so that systemic or local infection and inflammation compromise male fertility. The mechanisms underlying these interactions have begun to receive the attention from reproductive biologists and immunologists that they deserve, but many crucial details remain to be uncovered. A complete picture of male reproductive tract function and its response to toxic agents is contingent upon continued exploration of these interactions and the mechanisms involved.

Influence of autogenous leucocytes and Escherichia coli on sperm motility parameters in vitro

Urogenital infections are considered important factors in male infertility. In this in vitro study we have evaluated the impact of leucocytes in association with an artificial infection with Escherichia coli on the motility of human spermatozoa. Ejaculates and blood samples were obtained from healthy donors with normal semen parameters. Ejaculates were prepared by swim-up technique and five fractions were isolated for incubation. Leucocyte subtypes were separated from blood samples by gradient centrifugation. Purified sperm suspensions were adjusted to a concentration of 20 x 106 ml-1 and incubated with lymphocytes/ monocytes, polymorphonuclear granulocytes (PMN), and E. coli. Samples were incubated for up to 6 h at 37 degrees C. Motility analysis was performed using a computer-assisted sperm analyzer (CASA). Spermatozoa incubated with 3 x 106 PMN ml-1 revealed a significant (P=0.003) decrease in progressive motility after 2 h. This decrease remained weakly significant (P=0.024) after 4 and 6 h. Lymphocytes and monocytes had no effect on sperm motility. Spermatozoa incubated with granulocytes and E. coli demonstrated highly significant alterations in motility after 4 and 6 h of incubation (P < 0.001). The PMN indicate an effect on motility of spermatozoa under experimental conditions. However, the results suggest that bacteria are the primary agents that interfere with sperm motility.

Leukocyte detection in human semen using flow cytometry

This study set out to establish a new method, using flow cytometry, to evaluate leukocytes in semen. Ejaculates of 59 males, asymptomatic for genitourinary infections, were examined. Routine semen analyses were carried out as well as peroxidase and polymorphonuclear granulocyte-elastase detection. Leukocytes were detected combining flow cytometry and monoclonal antibodies (anti-CD45, anti-CD53). This technique reliably assessed the total number of leukocytes and differentiated subpopulations even at low concentrations. The peroxidase test and elastase determination showed good specificity, but only moderate sensitivity versus flow cytometry combined with monoclonal antibodies. No significant association was observed between semen parameters and leukocytospermia whether evaluated by conventional methods or flow cytometry except for a moderate correlation between spermatozoa and CD53-positive cell concentrations. A first comparison of data from patients grouped on the basis of leukocytospermia (>10(6) white blood cells, WBC/ml) or non-leukocytospermia revealed no significant differences in semen parameters; lowering the threshold value for leukocytospermia to 2x10(5) WBC/ml, sperm concentration was reduced in the group with a low number of WBC identified by monoclonal antibodies. Flow cytometry using monoclonal antibodies was seen to be a simple, reproducible method that enables leukocytes in semen to be accurately detected and to identify WBC subpopulations without preliminary purification procedures.

Antisperm antibodies and microorganisms in genital secretions--a clinically significant relationship?

In asymptomatic infertility patients, no significant relationship was found between the presence of antisperm antibodies (ASA) in serum and in semen samples (IgG and/or IgA ASA), differentiated with the mixed antiglobulin reaction (MAR), and the microbial colonization of ejaculates covering a broad spectrum of microorganisms. Likewise, there was no significant association of ASA with microbial findings in patients' female partners, who also presented without symptoms of genital tract infection and were screened at the same time. Furthermore, ASA in semen (IgG and IgA) were not significantly related to several potential markers of subclinical male sexual gland infection or inflammation (leukocytes, PMN elastase, albumin, C3c) evaluated in aliquots of the same ejaculates used for immunological testing.

Autoimmunogenicity of the human sperm protein Sp17 in vasectomized men and identification of linear B cell epitopes

OBJECTIVE

To assess whether human sera positive for antisperm antibodies have detectable levels of Sp17 autoantibodies and to determine the linear B cell epitopes to which these are raised for both native and recombinant Sp17.

DESIGN

Enzyme-linked immunoaborbent assays were performed against recombinant HSp17 on 15 serum samples from prevasovasostomy and postvasovasostomy patients. Positive sera then were used in mimotope analyses to determine HSp17 immunodominant linear B cell epitopes. These were compared with the linear B cell epitopes of recombinant HSp17.

SETTING

University research laboratory.

PATIENT(S)

Fifteen vasectomized or vasovasostomized men.

MAIN OUTCOME MEASURE(S)

Serum antibody reactivity to human Sp17.

RESULT(S)

Sera from vasectomized and vasovasostomized men exhibit Sp17 antibodies raised predominantly to two immunodominant linear B cell epitopes (amino acids 4 to 19 and amino acids 118 to 127), which differed from those of recombinant HSp17 (amino acids 52 to 79 and amino acids 124 to 136).

CONCLUSION(S)

The results show that Sp17 is an antigen to which vasectomized men raise autoantibodies. Two linear B cell epitopes predominate in native Sp17 and these differ from (but overlap with) those of the bacterially expressed recombinant protein.

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.

Complement-inhibiting activity of human seminal plasma and semen quality

Human seminal plasma (SP) contains potent complement inhibitors. This study examined the complement-inhibiting activity of individual SP samples from 118 patients with infertility and analyzed them in relation to various semen parameters. When 25% complement-inhibiting activity was considered the cut off value, less than 1 SD unit from the mean percentage of inhibition of SP samples with normal semen quality, 32 samples (27%) showed low inhibiting activity. Among the lower group, incidences of patients with asthenozoospermia (66%) and oligozoospermia (31%) were significantly (p < .01) higher than those (36 and 10%) in the group whose SP showed significant inhibiting activity. Partial characterization revealed that the component responsible for complement inhibition was heat labile, trypsin resistant, high molecular weight (>10 kD) glycoprotein that can inhibit alternative as well as classical complement pathways. Furthermore, since in the majority of SP samples the anticomplementary activity was blocked by monoclonal antibody against membrane cofactor protein (MCP) or decay accelerating factor (DAF), the complement-inhibiting factors that were identified are likely to be MCP and/or DAF, which are known to be present in human SP. These results suggest that complement-regulatory proteins in SP such as MCP and DAF may protect sperm cells against complement attack in the male reproductive tract.

Nonsperm cells in human semen: with special reference to seminal leukocytes and their possible influence on fertility

Nonspermatozoal cells (NSC) in semen, including immature germ cells, leukocytes (WBC) and epithelial cells, are normally found in a concentration less than 15% of the sperm concentration. Cytological staining methods and immunoenzymatic assays for characterization of seminal WBC and methods for detection of various enzymes from WBC are evaluated. Criteria for abnormally high levels of WBC in semen, caused by exogenic factors (e.g., infection) and possibly by endogenic factors (e.g., abnormal sperm), are discussed. Leukocytospermia is associated with reduced in vitro fertilization rate, and experimentally-measured sperm functions (e.g., motility) are inhibited by high concentrations of certain WBC products (e.g., reactive oxygen species and interferon-gamma). At the present stage, the following procedures could be used to evaluate WBC in ejaculates from infertile patients: (1) count the number of NSC using a hemocytometer. (2) Determine the number of WBC in percentage of NSC in smears using the Papanicolaou staining technique, or an immuno-enzymatic assay using monoclonal antibodies to the different kinds of WBC. (3) If, abnormally high levels of WBC (according to the WHO criteria or based on a percentile determined from examination of normal, fertile men) is detected, a second ejaculate should be examined 3 months later. (4) Persistent leukocytospermia should indicate physical and microbiological examinations, after which antibiotic treatment may be indicated.

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.

The biologic significance of white blood cells in semen

OBJECTIVE

To analyze the data available on the biologic significance of white blood cells (WBC) in semen of infertility patients.

DATA RESOURCES

The relevant literature was reviewed.

RESULTS

It is not possible to identify reliably WBC by conventional sperm staining techniques. The peroxidase method is sufficient for quantification of granulocytes, but immunocytology is the gold standard for the detection of all WBC populations in semen. Granulocytes are the most prevalent WBC type in semen (50% to 60%), followed by macrophages (20% to 30%) and T-lymphocytes (2% to 5%). The prevalence of leukocytospermia (> 10(6) WBC/mL semen) among male infertility patients is approximately 10% to 20%. There is controversy on the significance of WBC in semen. Whereas some authors did not observe sperm damage in the presence of leukocytospermia, others have found evidence that WBC are significant cofactors of male infertility: [1] seminal WBC numbers were higher in infertility patients than among fertile men; [2] leukocytospermia was associated with decreased sperm numbers and impaired sperm motility; [3] WBC damaged sperm function and hamster ovum penetration in vitro and were important prognostic factors for IVF-ET failure. Because of absence of clinical symptoms, the origin of WBC is difficult to determine. Normally, most WBC appear to originate from the epididymis because vasectomized men show very few WBC in semen. On the other hand, leukocytospermic samples show low citric acid levels, pointing to asymptomatic prostatitis as a source of WBC in semen. Surprisingly, approximately 80% of leukocytospermic samples are microbiologically negative. In some cases Chlamydia trachomatis might have triggered a persistent inflammatory reaction leading to leukocytospermia. Sperm damage by WBC can be mediated by reactive oxygen species, proteases and cytokines. Furthermore, genital tract inflammation facilitates the formation of sperm antibodies. As seminal plasma has strong anti-inflammatory properties and because there is only short contact between sperm and WBC in prostatitis and seminal vesiculitis, inflammations of the epididymis and testis are likely to have the largest impact on sperm.

CONCLUSIONS

There is ample evidence that WBC can affect sperm function. Further studies are needed to define cofactors that increase or decrease the risk of sperm damage by WBC.

Percoll density gradient centrifugation and consecutive flow cytometry do not identify leukocytes and leukocyte subtypes in ejaculate specimens

This paper describes an attempt to establish a new combined method of leukocyte analysis in human ejaculate by Percoll density gradient centrifugation and consecutive flow cytometry. As a first step, leukocyte separation was performed by Percoll density gradient centrifugation with consecutive enrichment of leukocytes, especially granulocytes, in the 40%/60% and 60%/80% Percoll interfaces. Then these fractions were stained with specific monoclonal antibodies and analysed in a Facscan flow cytometer. Flow cytometric analysis did not demonstrate identifiable leukocyte populations, indicating a questionable cross-reaction with spermatozoal elements. Therefore, the combined technique of Percoll density gradient centrifugation and flow cytometric analysis were considered unsuitable for clinical leukocyte determination.

Lack of expression of HLA antigens on immature germ cells from ejaculates with antisperm antibodies

PROBLEM

The lack of expression of HLA antigen on immature germ cells from ejaculates with antisperm antibodies has been reported.

METHOD

The expression of human leukocyte antigens on immature germ cells from ejaculates with antisperm antibodies (ASA) was investigated by indirect immunofluorescence using a panel of monoclonal antibodies (MAb) and automated flow cytometry. Patients were divided into two groups: fertile (prevasectomic; N = 10), and ejaculates with ASA (10 samples with IgG and IgA ASA, and five semen samples with only IgG ASA). ASA were detected on sperm using the direct immunobead test. After centrifuging semen samples on a Ficoll-Hypaque gradient, round cells obtained at the gradient interface were gated by a flow cytometer. The "immature germ cell window" was defined in terms of cellular volume and granularity.

RESULTS

The percentage of gated round cells from semen samples that reacted with anti-CD45 was always less than 5%, and with anti-CD44 less than 3%. This lack of reactivity of gated round cells with MAb specific for leukocytes and epithelial cells suggests that they were immature germ cells. Immature germ cells were unreactive with W6/32 and anti-beta-2-microglobulin MAb, which suggests that these cells do not express HLA class I molecules. Similarly, no reactivity of the immature germ cells with the MAb that recognize HLA class II molecules was found. No significant differences were observed in the expression of HLA molecules on immature germ cells between the different semen samples studied: fertile, and ejaculates with ASA.

CONCLUSION

The presence of ASA in ejaculate is not associated with abnormal HLA antigen expression on immature germ cells.

Leucocyte populations in semen and male accessory gland function: relationship with antisperm antibodies and seminal quality

Semen samples from 279 infertility patients attending an Immunological Centre were analysed to evaluate the relationship between the populations of leucocytes, seminal quality, antisperm antibodies, and seminal vesicle function. The most frequent finding between leucocytospermic samples was asthenozoospermia (57%), whereas in non-leucocytospermic samples normozoospermia was the most frequent finding (47%). In the samples with asthenozoospermia, granulocytes predominated, whereas in those with oligozoospermia and azoospermia a reduction in the number of macrophages and lymphocytes was observed, suggesting an obstructive process at the level of epididymis and/or vas deferens where these leucocytes are mostly produced. In the case of hypofunction of the seminal vesicles there was a predominance in granulocytes. The increased levels of each type of leucocytes affected seminal quality only when seminal vesicles were affected. Only the elevated granulocytes count was related to a decrease in sperm motility. In those samples with leucocytospermia, positive antisperm antibodies (ASA) were associated with low sperm motility, low sperm normal morphology, and low value of seminal corrected fructose, whereas, in the absence of leucocytospermia, ASA, were more related to low sperm counts. These data suggest that granulocytes were more related to seminal vesicles dysfunction and sperm motility changes, and that ASA may be observed in the presence or absence of leucocytospermia.

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.

Leukocytospermia and function of the seminal vesicles on seminal quality

OBJECTIVE

To determine possible relationships between number of leukocytes, function of seminal vesicles, and seminal quality.

DESIGN

The study was carried out on men who consecutively attended an infertility clinic between June 1989 to June 1991.

SETTING

This study was conducted in a private immunological center for infertility, a tertiary care center, The Centro Immunológico-Sección Esterilidad y Reproducción.

PATIENTS

Semen samples from 280 infertility patients attending an Immunological Center for Infertility were analyzed.

MAIN OUTCOME MEASURE

We evaluated the effect of leukocytospermia in the presence of normal or abnormal function of seminal vesicles on seminal quality.

RESULTS

Sperm count, percent of motile sperm, and percent of sperm vitality were significantly reduced when both leukocytospermia and hypofunction of seminal vesicles were present (P less than 0.01). Leukocytospermic subjects with normal function of seminal vesicles showed similar seminal parameters to those nonleukocytspermics. The incidence of subjects with antisperm antibodies measured by direct immunobeads was significantly higher in leukocytospermic men with hypofunction of seminal vesicles. No differences in the incidence of antisperm antibodies with nonleukocytospermic samples were observed in those with both leukocytospermia and normal function of seminal vesicles.

CONCLUSIONS

These data provide evidence that white blood cells were deleterious for seminal quality when seminal vesicles were also affected.

Seminal white blood cells in men with urethral tract infection. A monoclonal antibody study

Monoclonal antibodies were used to detect seminal leucocytes in 19 men with urethritis. A wide range in the number and type of leucocytes between individuals was documented (median 2.06 x 10(6)/ml, range 0.6-29.89 x 10(6)/ml); 22% of the men had less than 1 x 10(6) leucocytes/ml. The results suggest that the threshold of greater than or equal to 1 x 10(6)/ml proposed by the World Health Organisation to indicate genital tract infection is unsuitable for men with urethritis.

Detection of white blood cell populations in the ejaculates of fertile men

Using a now established, reliable technique for detecting white blood cells in human semen, we have examined the ejaculates of a fertile group of men. We have also highlighted the need for strict recruitment criteria to be established to enable accurate comparisons to be drawn between different patient groups and results from different laboratories.

Seminal peroxidase positive cells are not an adequate indicator of asymptomatic urethral genital infection

The relationship between asymptomatic urethral infection and seminal white blood cells, as detected using the peroxidase enzyme system, was examined. Eighty-four semen donors were tested. Twenty-four (29%) were diagnosed as having an active urethral genital infection. There was no statistical relationship between the total number of concentrations of peroxidase-positive cells and a urethral genital infection. Further studies should concentrate on the subtypes of seminal leucocytes and their surface receptors using monoclonal antibodies.