Prostaglandin E2 administered via anus causes immunosuppression in male but not female rats: a possible pathogenesis of acquired immune deficiency syndrome in homosexual males.

To explain a possible pathogenesis of acquired immune deficiency syndrome (AIDS) in homosexual males, we propose the following hypothesis. Prostaglandin E2 in human semen given via anus during anal intercourse may cause an immune dysregulation in the male semen recipients; this immunosuppressive effect of prostaglandin E2 may be one of the underlying factors that stimulate AIDS-associated virus infection or that trigger the latent AIDS-associated virus. This hypothesis is supported by the following experimental results. Anal infusion of prostaglandin E2 or D2 into male rats reduced in vitro responses of T lymphocytes to phytohemagglutinin. However, the T-cell response of female rats was not reduced significantly by the anal infusion of seminal prostaglandins.