H 0 plays a role in the thrombus formation 2 2 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 H 0 producing NADH-dependent system,which is by im munologic stimuli.By a biochemical methog,wequantified the H 202production(15 nmol/10 lets/20 min)after opsonized-zymosan(opZ)stimulation.We also demonstrated that platelets,by the membrane H 0 generating system,partecipate in non specifig immune mechanisms in the recru itment of inflammatory cells.The addition ofcatalase to platelet suspensions activated by opZ caused a 60% drop in the aggregation and in the release of ATP.lmmunologic stimuli caused a 40% decrease in platelet vit.E,which was inhibited by catalase.Our·data suggest that H 0 generating system could' play a role in the of DIe in childood.

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