Identification of Human Sperm Antigens to Antisperm Antibodies*

ABSTRACT: We have successfully applied SDS (so-dium dodecyl sulfate) gel/protein blot radioimmu-nobinding method to identify the molecular size of sperm antigens that elicit antisperm antibodies from patients with unexplained infertility. Following the transfer of renatured proteins from SDS gel of human sperm extract onto nitrocellulose strips, the radioim-munobinding was performed by incubating the strips with patients ' sera at 1:100 dilution and then with p25_ labeled goat antihuman immunoglobulin G (lgG) or protein A as detecting probes. Unique sperm anti-gens that reacted with some patients ' sera were iden-tified following the autoradiography of the incubated paper strips. Among the fifty-nine standard serum samples from the Reference Bank of the World Health Organization, about one-fourth of them were found to react predominantly with a sperm protein band having the reference value (Rf value) of 0.2 and the approximate molecular weight of 90,000 dalton. A similar analysis was also performed with serum sam-ples from vasectomized patients. Some of them also revealed a specific binding with the sperm antigents) of similar molecular weight. The results of this anal-ysis were also compared with those of conventional tests for sperm antibodies as well as those of micro-plate radioimmunoassays and enzyme-linked im-munoassays. This study suggests that SDS gel/pro-tein blot radioimmunobinding method can be a useful tool for the molecular identification of unique human sperm antigen(s) that elicit naturally occurring an-tisperm antibodies in patients with unexplained in