Suppressor T lymphocytes and cross-reactive sperm antigens in human semen

Studies were initiated to further explore possible interrelationships between semen and the immune system. Ejaculates from healthy donors were found to contain an average of 2.6 X 10(6) mononuclear cells and 0.8 X 10(6) lymphocytes. These seminal lymphocytes exhibited suppressor activity when co-cultured with autologous peripheral blood lymphocytes. Reactivity of monoclonal antibodies to all human T lymphocytes (OKT3) and to T suppressor/cytotoxic lymphocytes (OKT8) with purified T lymphocytes was shown by enzyme-linked immunosorbent assay (ELISA) to be reduced by 70-90% following pre-incubation of the antibodies with ejaculated human spermatozoa. Reactivity of mononuclear antibody to T helper/inducer lymphocytes (OKT4) with T lymphocytes was unaffected by spermatozoa. Since T suppressor lymphocytes present in sperm-containing fractions could be responsible for any reactivity of OKT3 and OKT8 antibodies with spermatozoa, lymphocyte-free sperm preparations were prepared. OKT3 and OKT8, but not OKT4, were shown by ELISA to react with purified human spermatozoa. Shared antigenic determinants between lymphoid cells and spermatozoa and/or the occurrence of lymphocytes in semen may, in some situations, induce alteration in immune functions following exposure to semen.