Production and release of platelet-activating factor (PAF); dissociation from degranulation and superoxide production in the human neutrophil

Abstract

The generation of human PAF was examined using purified neutrophils from normal and CGD donors. PAF release occurred in response to all of the neutrophil stimuli examined, including PMA and the calcium ionophore A23187, which initiate the relatively selective release of specific granule constituents. PAF release was dissociable from neutrophil degranulation by 1) the lack of correlation between PAF titers and extent of enzyme release for different stimuli, 2) the strict dependence of PAF release on the presence of extracellular Ca++, 3) the different kinetics for release of PAF and granule enzymes, and 4) the ability of neutrophils significantly depleted of azurophil and specific granule constituents to release normal levels of PAF when stimulated with opsonized zymosan. PAF release was also normal, if not elevated, in neutrophils from patients with chronic granulomatous disease, demonstrating that the formation and release of PAF does not depend upon an intact superoxide generating pathway.