Abnormal distribution of epididymal antigens on spermatozoa from infertile men.

An antiserum raised against human epididymal proteins associated with ejaculated sperm was used to test the hypothesis that the amount and/or localization of these antigens may be altered in men with infertility. With the use of immunofluorescence we found that in sperm from fertile donors 88.4% of the cells had the antigens localized over the acrosomal cap only and 1.3% had most of the antigens at extraacrosomal sites. Fifteen of the 26 infertile men (P1) studied had a similar relative distribution of antigens, but the remaining 11 patients (P2) had a 38-fold increase in cells with extraacrosomal localization of the antigens (40%, P less than 0.005). Using flow cytometry to quantitate immunofluorescence, content of antigen on sperm from patients from population P1 (680 +/- 60 V X 10(-4)) was not different from that of control (835 +/- 53 V X 10(-4], whereas it was significantly lower in sperm from patients from population P2 (554 +/- 64 V X 10(-4), P less than 0.005). Differences could not be correlated with parameters measured by routine semen analysis. Our results suggest a possible relationship between the decreased amount of epididymal antigens or their altered localization on sperm and the infertility of patients from population P2.