The existence of NADPH oxidase in fish neutrophils

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During respiratory burst, eel neutrophils consumed oxygen, and produced active oxigens. Superoxide production was equivalent to oxygen consumption, and hydrogen peroxide production was approximately half of oxygen consumption or superoxide production. This correlation is stoichiometrically identical to that of oxygen metabolism caused by NADPH oxidase during the respiratory burst in mammalian phagocytes, demonstrating the existence of the similar mechanism of oxygen radicals in fish neutrophils to mammals. The amounts of ocygen consumed and oxygen radicals produced in irritant-elicited neutrophils were significantly higher than those in unelicited neutrophils. This indicates that elicited neutrophils which possess high bactericidal activity were released from hematopoietic tissue to inactivate an exclude foreign irritants.Cytochrome b558 is a membrance-bound component of NADPH oxidase present in mammalian phagocytes, and consisted of large and small subunits. Anti-Li antigocy against the synthetic peptide corresponding to the carboxyl terminal of human cytochrome b558 large subunit was produced. When western blotting was performed against Japanese ell neutrophil lysate, a broad band was specifically detected with the antibody at 80-110 kDa as well as human neutrophil smaple. Fluorescent antibody technique shows that the antibody recognized the epitope existed in eel neutrophils only after the cells were permeabilized with detergent. These results demonstrate tha the large subunit of cytochrome b558 exists in fish neutrophils and the caboxyl terminal is exposed to cytoplasmic sede, and suggest that NADPH oxidase is conserved in neutrophils across species.