The role of prostaglandin E2 in seminal immunosuppression.

Seminal plasma, which has high antigenic potential and the capacity to induce immunosuppression, has been incriminated as a possible factor in the acquired immunodeficiency syndrome (AIDS). Seminal plasma contains high concentrations of prostaglandins, which are capable of inducing immunosuppression. As prostaglandin E2 is noted for its immunosuppressive actions, we designed this study to determine whether this prostaglandin is responsible for seminal immunosuppression. Diluted and undiluted samples of semen from 5 heterosexual donors induced a significant suppression of phytohaemagglutinin-stimulated thymidine incorporation into lymphocytes. However, when the prostaglandin E2 levels of the semen samples were extrapolated to a standard prostaglandin E2 dose-response curve, the estimated values did not agree with the prostaglandin E2 levels. We conclude that prostaglandin E2 may contribute to seminal immunosuppression, but is not solely responsible for it.