Effect of platelet-activating factor on human polymorphonuclear leukocyte enhancement of chemiluminescence and antibody-dependent cellular cytotoxicity.

The effect of platelet-activating factor on human granulocytes was determined by luminol-dependent chemiluminescence (CL), antibody-dependent cellular cytotoxicity (ADCC), and rosette assay. An activation of the respiratory burst could be measured by CL and be shown to depend on the presence of extracellular calcium. This direct stimulation of PMN was proved to be inhibited by oxygen radical scavengers as well as by the calcium channel blocker diltiazem. Furthermore, the presence of PAF enhanced the activation of PMN via Fc- or C3b-receptors, as demonstrated by CL and ADCC. On the other hand, no influence on the rosette-forming capacity of PMN could be detected. The results support the concept of the import role of PAF in inflammatory processes.