Studies on the immunosuppressive effect of seminal plasma.

In vitro suppression of immune responses by seminal plasma is well documented, but the mechanism by which it exerts its effects remains to be established. Our studies on T-lymphocyte proliferation and natural killer cell target-cell lysis reveal that seminal plasma mediated suppression is dose-dependent and temperature-dependent, and that cells which have been activated are less susceptible to suppression. In the case of mitogen-induced T-cell responses this results in a decrease in the expression of the Interleukin-2 receptor whose generation is essential to T-cell proliferation. These studies provide further evidence about suppression of the immune response by seminal plasma. This may be a contributory factor in the aetiology of AIDS, other sexually transmitted diseases, infertility and malignancies of the urogenital tract including carcinoma of the cervix.