Auto- and iso-antigens of human spermatozoa detected by immunoblotting with human sera after SDS-PAGE.

A sodium dodecylsulphate-polyacrylamide gel electrophoretic system for analysis of the proteins of human spermatozoa was established. Subsequent immunoblotting of the gels with human sera gave a reproducible immunolabelling of distinctive polypeptide bands. To identify auto- and isoantigens, 28 well-characterized sera from the WHO Reference Bank for Reproductive Immunology (1977, Acta Pathol. Microbiol. Scand. Sect. C, Suppl. 252) containing agglutinating and complement fixating antibodies (9 female (F) and 19 male (M) and 30 normal sera (14 F and 16 M) were analysed with reference to binding of IgG. Three spermatozoal antigens with Mr values in reduced state of 120,000 (6), 41,000 (6) and 32,000 (15) were found to be specifically correlated to the agglutinating activity of the reactive sea. (The number of these are given in parentheses). Furthermore, IgG from 2 and 3 of the normal sera and 14 and 17 of the agglutinating sera reacted with 78 and 64 kDA polypeptide, respectively. Identical binding patterns of IgG to spermatozoal polypeptides were obtained with IgG from male and female sera. The IgG-binding could not be correlated to the modes of spermatozoal agglutination. In a similar analysis of the IgM binding antigens of 21 agglutinating and 12 normal sera no differences in binding between the sera were found, except for a specific reaction to a 78 kDa antigen for 5 of the agglutinating sera.