Platelet-activating factor acetylhydrolase in human seminal plasma

To search for the presence of platelet-activating factor (PAF) acetylhydrolase activity in human seminal plasma. Experimental. Reproductive laboratory in a university-affiliated hospital research center. Human male volunteers were selected on the basis of apparent normal health. Human seminal plasma contained significant levels of PAF-acetylhydrolase activity. Enzymatic hydrolysis of PAF displayed typical kinetics and was a calcium-independent process. Platelet-activating factor acetylhydrolase in seminal plasma was associated with a very high-density lipoprotein fraction. Enzymatic activity was independent of sperm count and motility. Human seminal plasma contains significant levels of PAF acetylhydrolase. This enzyme may be an important factor in the regulation of PAF concentration and activity.