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

W-B irradiation of blood-platelet concentrates is used in transfusion practice to prevent the development of post-transfusion alloimmunization and inactivate 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 the chemiluminescence method (respectively 28 and 148.6% above the control). The superoxide radical level after UV-B irradiation measured by the cytochrome c reduction method shows only a slight increase (p > 0.05). Free radical generation induced by UV-B radiation is dependent partly on blood-platelet activation and enzymatic pathways, since we have shown that wortmannin, an inhibitor of phosphatidylinositide 3-kinase, reduces the level of radicals formed in blood platelets after W-B irradiation. This indicates that free radicals generated in blood platelets after stimulation by UV-B radiation are involved in platelet activation and metabolism of platelet polyphosphoinositides. (C) 2000 Elsevier Science S.A. All rights reserved.