Characterization of monoclonal antibodies against human sperm antigens by immunoassays including sperm function assays and epitope evaluation.

Fifteen monoclonal antibodies (MAbs) raised against human sperm cells were evaluated for reactions against human sperm by indirect immunofluorescence, immunocytochemistry, agglutination, complement-dependent immobilization, cervical mucus penetration, and hamster egg penetration assays. The MAbs were analyzed for specificity by immunofluorescent reactions with peripheral blood lymphocytes and sperm and classified into three main groups based on regional staining, ie, acrosome, plasma membrane, or tail. One MAb (218) bound to the sperm neck. Three MAbs, (80, 85, and HS-126) were found to react with lymphocytes. Three of five acrosome-reactive MAbs (11, 63, 106), two of five tail-staining MAbs (97, HS-30), and the neck reactor (218) showed significant to highly significant inhibition of sperm penetration of eggs but without significant effects on sperm agglutination, immobilization, or the mucus penetration assay. The three non-specific MAbs gave strong plasma membrane reactions in the agglutination and immobilization assays and also caused highly significant inhibition of sperm penetration of both cervical mucus and zona-free ova. Preliminary analysis of the complementary antigens suggested that epitopes reacting with MAbs 33 (acrosome) and 85 (plasma membrane) were carbohydrate chains on glycoproteins. Three of five MAbs recognizing tail antigen, the neck-staining MAb, and the non-specific MAb (HS-126) appeared to be reactive against glycolipid moieties. Seven of the 12 specific MAbs also reacted in indirect immunofluorescence with mouse and rabbit sperm in patterns similar to those observed with human sperm.