CHARACTERIZATION OF A SPERM COATING AUTOANTIGEN REACTING WITH ANTISPERM ANTIBODIES OF INFERTILE MALES USING MONOCLONAL-ANTIBODIES

Objective In a previous study a number of sperm-specific antigens were identified which reacted with antisperm antibodies from both infertil e and vasovasostomised males. To investigate the localisation and dist ribution of these antigens and their role in male fertility, monoclona l antibodies were raised against them; immunoblotting techniques were used to select only those antibodies which competed with human antispe rm antibodies for these human auto-antigens. Design One antibody, NW21 , reacted with an 18 kDa auto-antigen present on epididymal sperm but absent from testicular sperm. Immunohistochemical studies showed that the antigen is produced in small basal cells between the columnar epit helium of the corpus epididymis, passes up into the tubule and then co ats sperm passing along the epididymis. Sperm stored in the cauda epid idymis and ductus deferens stain strongly for this sperm coating glyco protein. Conclusions The localisation of this antigen supports the sug gestion that auto-immune infertility may represent a response to epidi dymal rather than testicular sperm. Monoclonal antibodies raised to un ique and immunologically accessible sperm coating proteins, produced i n the epididymis rather than in the testis, would seem to present an e xcellent theoretical solution to male contraception.