Histoimmunochemical localization of three guinea-pig spermatozoal autoantigens.

By the indirect immunofluorescence technique three distinct guinea-pig spermatozoal autoantigens named S, P and T have been localized. Autoantigen S is present on proacrosomal granules, acrosomal granules, acrosome and head cap of spermatids and spermatozoa. Autoantigen P is present on the same formations except the head cap. Autoantigen T is also localized on acrosomes and head caps but probably on their membranes as well as on the cytoplasmic membranes of spermatozoa and spermatids. These three autoantigens are testis specific since they were not found in other organs in guinea-pigs; moreover S was detected on the acrosomal apparatus in rabbits, rats and mice. The natural antispermatozoal antibodies found in guinea-pig serum do not combine with autoantigens S and P, but the possibility that they could react with autoantigen T is considered. The cytological localization of S, P and T together with their previously described physicochemical and immunological properties allow a tentative explanation of their and immunopathological properties.