Free-radical and cyclooxygenase-catalyzed lipid peroxidation in membranes of blood cells under UV irradiation.

The data on the role of lipid peroxidation in the effects of UV irradiation of blood are reviewed. Lipid photoperoxidation in blood cells is the result of photochemical transformation of lipid hydroperoxides, both existing and newly formed ones, into free radicals and direct photolysis of photooxidants. Dark lipid autoperoxidation is also induced by UV radiation. Both peroxidation and photooxidation of lipids are inhibited by low concentrations of antiradical antioxidants. The cyclooxygenase-catalyzed peroxidation of arachidonic acid in blood cells is stimulated by UV radiation. This process is suppressed by acetylsalicylic acid and indomethacin. The therapeutic activity of the blood that was UV-irradiated and then infused into rats with peritonitis was due to the cyclooxygenase activation.