Effect of boar seminal immunosuppressive fraction on B lymphocytes and on primary antibody response.

Repeated i.p. or rectal treatment of male and female mice with an immunosuppressive component isolated from boar seminal vesicle secretion reduced responses of B lymphocytes to mitogen as evaluated by [3H]thymidine or bromo-deoxyuridine incorporation. The proliferative activity of T lymphocytes was not affected. By means of the immunofluorescence method, the seminal immunosuppressive component was detected on the membranes of B lymphocytes separated from the spleens of mice treated in vivo with immunosuppressor. An i.p. injection or rectal infusion of the immunosuppressive component also led to a suppression of primary antibody response to soluble and particulate antigens. These findings indicate that in vivo deposition of semen may compromise some aspects of the immune system and may be an important cofactor in the development of viral and bacterial infections in homosexual men.