Characterization of humoral antibodies reactive with spermatozoa, N-acetyl galactosamine, and a putative blood group antigen in seminal plasma

Antisperm antibodies in sera of infertile women may react differently with spermatozoa of different men. We studied the reactivity of these antibodies with spermatozoa from men of varying blood group status. Increased immunoglobulin binding to sperm of group A or AB men was noted compared with group O men. A diminution in binding of immunoglobulins to spermatozoa after absorption of these sera with human group A or AB red blood cells was noted as well as after coincubation of sera and sperm with N-acetyl galactosamine, the terminal sugar of blood group antigen A. These observations suggest that antibodies directed against blood group antigens adsorbed to sperm of secretor males may account in part for variations in immunobead binding levels between sperm of different men.