H₂O₂ GENERATING SYSTEM IN HUMAN BLOOD PLATELETS

Abstract

H₂O₂ plays a role in the thrombus formation in the endotoxin-induced disseminated intravascular coagulation(DIC) in rats.It has been al so shown that antioxidants,such as vit.E,could prevent the aggregation of platelets in this experimental DIC.It is now evident that human platelets produce oxidizing substances.Using a cytochemical ultrastructural method; we demonstrated that platelets carry an H₂O₂ producing NADH-dependent system,which is activated by im munologic stimuli.By a biochemical method,we quantified the H₂O₂ production(15 nmol/10⁹ plate lets/20 min)after opsonized-zymosan(opZ)stimulation.We also demonstrated that platelets,by the membrane H₂O₂ generating system,partecipate in non specific immune mechanisms in the recruitment of inflammatory cells.The addition of catalase to platelet suspensions activated by opZ caused a 60% drop in the aggregation and in the release of ATP.Immunologic stimuli caused a 40% decrease in platelet vit.E,which was inhibited by catalase.Our data suggest that H₂O₂ generating system could play a role in the pathogenesis of DIC in childood.

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