UV-B-induced generation of free radicals in blood platelets

W-B irradiation of blood-platelet concentrates is used in transfusion pract ice to prevent the development of post-transfusion alloimmunization and ina ctivate viruses and bacteria in the concentrates. W-B radiation may affect the blood-platelet metabolism and function; therefore we have investigated the effect of W-B irradiation on free radical production in blood platelets . Our results show that exposure of pig blood platelets to W-B radiation (0 .36 and 1.08 J/cm(2)) induces the generation of free radicals measured by t he chemiluminescence method (respectively 28 and 148.6% above the control). The superoxide radical level after UV-B irradiation measured by the cytoch rome c reduction method shows only a slight increase (p > 0.05). Free radic al generation induced by UV-B radiation is dependent partly on blood-platel et activation and enzymatic pathways, since we have shown that wortmannin, an inhibitor of phosphatidylinositide 3-kinase, reduces the level of radica ls formed in blood platelets after W-B irradiation. This indicates that fre e radicals generated in blood platelets after stimulation by UV-B radiation are involved in platelet activation and metabolism of platelet polyphospho inositides. (C) 2000 Elsevier Science S.A. All rights reserved.