Influence of antisperm antibodies on human sperm function.

Antisperm antibodies have been found in about 8% of men with infertility and in 60 to 80% of patients following vasectomy. In order to investigate the way antibodies influence sperm function we studied serum and seminal plasma from patients with infertility (n = 61) or undergoing vasovasostomy (n = 25). These antisera were characterised to determine their TAT titre, the nature of the target antigens and their capacity to interfere directly with fertilisation. The results indicate that antibodies from both groups of patients exhibit a capacity to stimulate or suppress sperm/oocyte fusion. The proportion of samples showing stimulatory activity was higher (50%) in the vasovasostomised population than in patients with infertility (21%). The remainder of the antisera suppressed sperm/oocyte fusion. There was no correlation between the titre of antisperm antibodies and their capacity to influence sperm function, indicating that it is the nature of the target antigens which is of significance rather than the antibody concentration. Western blot analysis indicated that these antisera targeted a group of sperm surface antigens with molecular weights of 30kD (35,45,66,90 and 115kD). Monoclonal antibodies are now being prepared in order to determine which of these specific components are involved in the suppression of sperm function.