NITRIC-OXIDE REGULATES THE CHEMILUMINESCENCE FROM STIMULATED HUMAN NEUTROPHILS

Nitric oxide, produced from L-arginine by a variety of cells, is a bio logically active compound that can react with iron and thiols. The obj ective of this study was to investigate the effects of nitric oxide on the respiratory burst from human neutrophils. Treatment with nitropru sside increased the chemiluminescence from neutrophils stimulated with PMA or collagen, but not from cells stimulated with FMLP. Addition of L-arginine increased the chemiluminescence after stimulation with any of the three stimuli, while Nw-nitro-L-arginine methyl ester decrease d it. Low doses of nitric oxide, either endogenously or exogenously pr oduced, probably inhibited catalase or glutathione, leading to an incr ease in hydrogen peroxide available for chemiluminescence detection. T his indicates that nitric oxide may reduce the protection against hydr ogen peroxide in tissue and in invading catalase-positive bacteria.