EFFECT OF SODIUM AZIDE ON CHEMILUMINESCENCE OF GRANULOCYTES - EVIDENCE FOR GENERATION OF MULTIPLE OXYGEN RADICALS

Abstract

Granulocytes generate superoxide .**GRAPHIC**. as well as H2O2 during phagocytosis. The chemiluminescence (CL) generated by phagocytes appears dependent on these O2 radicals (OR). Recent studies suggest that O2 molecules, including singlet (1O2) or hydroxyl radicals .**GRAPHIC**. may also be generated during phagocytosis and contribute to the CL. Human granulocyte CL was studied in the presence of 0.1 mM sodium azide, a known inhibitor of myeloperoxidase and catalase and a scavenger of 1O2. The effects of azide on CL were correlated with the effects of this compound on hexose monophosphate shunt (HMPS) activity, nitroblue tetrazolium (NBT) dye reduction, formate oxidation and cytochrome c reduction. CL generated by granulocytes during the phagocytosis of zymosan particles was markedly impaired by azide (24-47% of control values). Phenomena dependent in part on the presence of O2 radicals, i.e., reduction of NBT dye and cytochrome c, were apparently not impaired by the presence of azide. Inhibition of catalase by azide virtually abolished the oxidation of formate, but the burst in HMPS activity associated with phagocytosis was further augmented. The latter observation indicates that azide did not impair generation of H2O2 but increased the relative amount detoxified via the HMPS. Radicals other than .**GRAPHIC**. and H2O2 seem to be generated during phagocytosis and these radicals may be major contributors to the CL phenomenon.