Bacterial Killing by Phagocytes: Potential Role(s) of Hypochlorous Acid and Hydrogen Peroxide in Protein Turnover, DNA Synthesis, and RNA Synthesis
Although phagocytic cells clearly play a primary role in host defense against bacterial infection, the exact mechanisms of bacterial killing are largely unknown. Stimulation of an NADPH oxidase system during the “respiratory burst” in phagocytes generates a series of oxidants. Molecular oxygen is reduced to superoxide which then rapidly dismutates to form hydrogen peroxide (H2O2). Myeloperoxidase from phagocyte granules then uses the H2O2 to oxidize chloride ions to form hypochlorous acid (HOCl). The importance of these oxidants is underscored by studies of patients with chronic granulomatous disease (CGD). CGD patients suffer severe, recurrent bacterial infections (with catalase postive bacteria) because their neutrophils are unable to reduce oxygen to superoxide. The exact role(s) of oxygen metabolites (thought to act synergistically with cytotoxic proteins) in bacterial killing remain(s) undetermined.
KeywordsProtein Degradation Chronic Granulomatous Disease Hypochlorous Acid Form Hydrogen Peroxide Bacterial Killing
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