Effect of human seminal plasma on the lytic activity of natural killer cells and presumptive identification of participant macromolecules.

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