Autoimmunity to sperm antigens in vasectomized men

Sera from vasectomized men were tested for the presence of antibodies directed against sperm antigens. A high percentage (about 55%) of the vasectomized men developed agglutinating antibodies. A lower percentage (22%) also developed low titres of antibodies to human protamine, as detected in the indirect IFT on swollen sperm heads and 22% developed cytotoxic antibodies. A correlation was found between the presence of anti-protamine antibodies and the presence of agglutinating and of cytotoxic antibodies. This correlation, and also the fact that they developed after vasectomy, indicates that the formation of antibodies against human protamine is a result of an autoimmune response to spermatozoa. The indirect IFT was also performed on 'normal' unswollen spermatozoa. All the sera were positive at least on one of the sperm antigens located in the acrosome, equator, or post-nuclear region, but no increase nor decrease in titre was found after vasectomy.