Evidence for production of oxidizing radicals by the particulate O₂^--forming system from human neutrophils

The particulate O₂^- forming system from human neutrophils was found to oxidize methional and 2-keto-4-methylthiobutyric acid (KMB) to ethylene, indicating the formation by this system of strongly oxidizing radicals. Conforming this interpretation was the observation that ethylene production was inhibited by the radical scavengers benzoaste, ethanol, and mannitol. Ethylene production was also sharply reduced by superoxide dismutase, implicating O₂^- as a precursor of oxidizing radicals. In our system catalase only partially inhibited ethylene generation from either methional or KMB, suggesting that oxidizing radicals are generated at least in part by the reaction of O₂^- with compounds other than H₂O₂. We propose that in neutrophils oxidizing radicals are formed in a reaction between O₂^- and a peroxide according to the following equation: O₂^- + ROOH ?RO OH^- O₂ in which ROOH may be hydrogen peroxide, an alkyl peroxide, or an acyl peroxide (i.e, a peroxy acid).