The Hydroxyl Radical Formation System in Polymorphonuclear Leukocytes

概要

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We studied the hydroxyl radical (OH・)-generating system in polymorphonuclear leukocytes (PMNs). When phenylalanine was incubated with the α, β and γ fractions prepared from pig polymorphonuclear leukocytes (PMNs) and hydrogen peroxide (H_2O_2), significant levels of formation of m- and o-tyrosine were observed in the α and β fractions, but not in the γ fraction. The amount of tyrosine formation per milligram of protein was greater with the β than with the α fraction. Further, when phenylalanine was incubated with α or β fractions with similar myeloperoxidase (MPO) activities in the presence of H_2O_2,tyrosine formation by the β fraction was also more effective. Using the β fraction in which the MPO activity was destroyed by heat treatment, no significant amount of tyrosine was formed. However, with the heat-treated β fraction and MPO preparations from human neutrophils in the presence of H_2O_2,the amount of tyrosine formation increased with the addition of increasing amounts of heat-treated β fraction. Tyrosine formation by the β fraction in the presence of H_2O_2 was significantly reduced by OH・scavengers. The above results suggest the existence of an OH・-generating system in which MPO and H_2O_2 participate in the granules of PMNs and, especially, in specific granules, there may exist some factors that cause more effective OH・generation.
公益社団法人日本薬学会の論文
1999-10-15