A comparison of sperm antibody assays

Sperm acrosome status and sperm antibodies in infertility

PURPOSE

We studied whether the spermatozoa from sperm autoimmune infertile men undergo premature acrosomal loss and whether this relates to the presence of sperm antibodies in wives.

MATERIALS AND METHODS

We evaluated acrosome status of live washed native and overnight capacitated spermatozoa from 17 sperm nonautoimmune fertile and 23 sperm autoimmune infertile men using an immunofluorescent peanut lectin binding assay. We used cytotoxic and immunobead binding assays to prescreen the serum and seminal plasma of these men, and serum and cervical mucus of the wives for immunological infertility. We performed immunofluorescent sperm antibody assays on all study samples to ascertain sperm antibody isotype levels in each sample. Levels of acrosomal loss in husband native and capacitated spermatozoa were correlated with levels of IgG, IgA and IgM sperm antibodies in the study samples.

RESULTS

Sperm autoimmune infertile men had a significantly larger percentage of sperm (p <0.0001) that had lost the acrosome and a lower percentage of sperm with intact acrosome (p <0.0001) in native and capacitated preparations in contrast to those of fertile controls. Levels of cytotoxic and IgA antibodies, especially in seminal plasma and cervical mucus, correlated significantly with percentages of sperm with a total loss of acrosome in native and capacitated sperm preparations (p < or = 0.01).

CONCLUSION

Infertile men with sperm antibodies in serum and seminal plasma undergo premature acrosome loss. This loss may expose the reproductive tract immune system, especially that involving IgA, in autoimmune infertile men and the wives to high immunogenic levels of sperm acrosome membrane antigens, thereby rendering them immunologically infertile.

The presence of a C1-inhibitor-like molecule (C1-INH-L) on human sperm: its involvement in sperm motility

PROBLEM

An 88-92-kDa C1-inhibitor-like molecule (C1-INH-L) was previously identified to elicit cytotoxic sperm antibody response in infertile men and women. Here, we document that it is present on the human sperm surface and could be detected by an enzyme-labeled immunoglobulin G (IgG) fraction of anti-human C1-INH antibody.

METHOD OF STUDY

Western blot analysis, enzyme-lined immunoadsorbent assay (ELISA) and computerized sperm motion analysis.

RESULTS

The existence of C1-INH-L on the sperm surface is calcium independent. Phosphatidylinositol-specific phospholipase C (PIPLC), EDTA, and acid (pH 3.0) could not remove the C1-INH-L from sperm, but trypsin did. Activated C1s was able to bind to the sperm surface. Immunofluorescence studies localized the protein to the head and midpiece of the sperm membrane. The C1-INH-L exists on both uncapacitated and capacitated sperm surfaces, which suggests that this protein is a sperm-surface protein. The heat-treated (56 degrees C, 30 min) IgG fraction of anti-C1-INH greatly reduced the percentage of motile spermatozoa and the progressive and path velocities in the absence of complement.

CONCLUSION

Our data suggest that C1-INH is a sperm membrane-anchored protein that may have complement and sperm motility regulatory function.

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.

Interlaboratory interprotocol comparison of indirect immunobead assay for sperm-associated antibodies in serum

This investigation was designed to study the effect of two different protocols on the indirect sperm-associated antibody test on serum performed using Bio-Rad immunobead (IBT) at two andrology laboratories. Aliquots of 31 serum samples from infertile couples were analyzed by both protocols. The IBT was negative by both protocols (100% concordance) for 18 serum samples. Seven of the 13 remaining samples were positive by both protocols (> or = 10% bead attachment by protocol A and > or = 20% bead attachment by protocol B), for a concordance of 54%. The remaining six samples were positive by one of the two protocols. The overall concordance for positive and negative results was 81% (25 of 31 samples). Protocol A detected a higher percentage of bead attachments for IgG and IgA, while protocol B detected a higher percentage of bead attachments for IgM. The discordance in the results of IgA attachment obtained by the two protocols was statistically significant (p < .05). A standardized, uniform protocol for the indirect IBT is needed.

Variation in antisperm antibody results using different assays

PROBLEM

The detection of various types of antisperm antibodies (ASA) in the serum varies among different assays. This variation may influence the diagnosis and management of infertile couples who are tested for such immunologic factors. This prospective study was conducted to determine the variation in the results of ASA as measured by the sperm immobilization (SI), sperm agglutination (SA), and the indirect immunobead (IB) assays.

METHOD

The sera of 79 patients that tested positive for ASA by at least one of the assays listed above were concurrently tested with all three assays.

RESULTS

Using an individual ASA assay, 66 (84%), 26 (33%) or 36 (46%) of sera tested positive by the SA, SI, or IB assays, respectively. However, using a combination of assays, 67 (85%), 78 (99%) or 40 (51%) of sera tested positive using either the SA+SI, SA+IB or SI+IB assays, respectively.

CONCLUSION

These findings suggest that the utilization of different assays to detect ASA may detect sera that are positive for ASA with more reliability than single assay testing.

A comparison of enzyme-linked immunosorbent assay (ELISA) with sperm immobilization test (SIT) in detection of antisperm antibodies in sera of infertile women

In the present study, an enzyme-linked immunosorbent assay (ELISA) for antisperm antibodies was compared with a traditional standard sperm immobilization test (SIT) in sera from 158 infertile women in order to evaluate their clinical usefulness for various causes of infertility. Ten pregnant and unmarried women were used as the control group. There was a higher incidence rate by ELISA (13.9%) compared with that by SIT (10.1%) after examination of overall samples, although the difference was not statistically significant. The unexplained infertility group exhibited the highest incidence among the various causes of infertility in both of these two methods. Fifteen (93.8%) of 16 patients with positive SIT showed positive reaction in ELISA method, indicating that a close correlation exists between the two methods. The positive predictive value (54.5%) of ELISA was significantly (p < 0.05) lower than that (87.5%) of SIT, as evaluated with the results of postcoital test (PCT) performed at periovulatory phase. This suggests that the ELISA method for antisperm antibodies is less specific than SIT in view of the PCT results. Nevertheless, no fresh sperms are not required for the ELISA examination. Thus, it seems that the ELISA method may provide a convenient and practical means for mass screening in detecting antisperm antibodies in clinical practice.

Antigens in capacitated spermatozoa eliciting autoimmune responses

We studied the possible qualitative antigenic differences between native and capacitated spermatozoa pertaining to immunological infertility. Western blot analysis was used to test serum and seminal plasma immunoglobulin G (IgG) from 18 infertile couples with sperm antibodies, and 14 fertile men and 9 fertile women without significant sperm antibodies against native and capacitated spermatozoa from fertile and infertile men. More fertile and infertile subjects had serum and seminal plasma IgG binding to antigens with molecular weights of 34/36, 46, 68, 97, 105, 115, 120, 130, 150 and 190 kDa. in capacitated versus native spermatozoa of all men. Of the other hand, immune reactivity to antigens with molecular weight 22/24, 30, 32, 50, 80, 88/92 and 180 kDa. found in native autoimmune spermatozoa was strongest in infertile couples with sperm antibodies. This reactivity significantly increased against capacitated autoimmune spermatozoa. Native spermatozoa from few fertile men had these antigens but they appeared after capacitation. It seems that certain antigens normally appearing or enhanced after capacitation are already present in native spermatozoa from infertile men, probably due to an inherent aberration or premature capacitation. This might account for the observed enhanced immune responses in infertile couples to sperm antigens from infertile husbands.