Effect of Human Seminal Plasma on the Lytic Activity of Natural Killer Cells and Presumptive Identification of Participant Macromolecules

ABSTRACT: Using the lytic activity of natural killer (NK) cells as an in vitro parameter, the immunoregulatory properties of human seminal plasma (SeP1) and participant macromolecules have been investigated. Significant (P < 0.05) suppression of NK cell activity by SeP1 and chromatographically separable fractions was demonstrated in association with high and low molecular weight (M_r) macromolecules. SePl suppression was retained after heating to 56°C for 30 min, and appeared to function at the level of the effector, rather than target cell. Physicochemical characterization of high and low M_r fractions provided presumptive identification of the participation of transglutaminase and prostaglandins as the principal molecules contributory to SeP1 immunosuppression.