TY - JOUR
T1 - Spin trapping evidence for myeloperoxidase-dependent hydroxyl radical formation by human neutrophils and monocytes
AU - Ramos, C. L.
AU - Pou, S.
AU - Britigan, B. E.
AU - Cohen, M. S.
AU - Rosen, G. M.
PY - 1992
Y1 - 1992
N2 - Using the electron spin resonance/spin trapping system, 4-pyridyl 1-oxide N-tert-butylnitrone (4-POBN)/ethanol, hydroxyl radical was detected as the α-hydroxyethyl spin trapped adduct of 4-POBN, 4-POBN-CH(CH3)OH, from phorbol 12-myristate 13-acetate-stimulated human neutrophils and monocytes without the addition of supplemental iron. 4-POBN-CH(CH3)OH was stable in the presence of a neutrophil-derived superoxide flux. Hydroxyl radical formation was inhibited by treatment with superoxide dismutase, catalase, and azide. Treatment with a series of transition metal chelators did not appreciably alter 4-POBN-CH(CH3)OH, which suggested that hydroxyl radical generation was mediated by a mechanism independent of the transition metal- catalyzed Haber-Weiss reaction. Kinetic differences between transition metal- dependent and -independent mechanisms of hydroxyl radical generation by stimulated neutrophils were demonstrated by a greater rate of 4-POBN- CH(CH3)OH accumulation in the presence of supplemental iron. Detection of hydroxyl radical from stimulated monocyte-derived macrophages, which lack myeloperoxidase, required the addition of supplemental iron. The addition of purified myeloperoxidase to an enzymatic superoxide generating system resulted in the detection of hydroxyl radical that was dependent upon the presence of chloride and was inhibited by superoxide dismutase, catalase, and azide. These findings implicated the reaction of hypochlorous acid and superoxide to produce hydroxyl radical. 4-POBN-CH(CH3)OH was not observed upon stimulation of myeloperoxidase-deficient neutrophils, whereas addition of myeloperoxidase to the reaction mixture resulted in the detection of hydroxyl radical. These results support the ability of human neutrophils and monocytes to generate hydroxyl radical through a myeloperoxidase-dependent mechanism.
AB - Using the electron spin resonance/spin trapping system, 4-pyridyl 1-oxide N-tert-butylnitrone (4-POBN)/ethanol, hydroxyl radical was detected as the α-hydroxyethyl spin trapped adduct of 4-POBN, 4-POBN-CH(CH3)OH, from phorbol 12-myristate 13-acetate-stimulated human neutrophils and monocytes without the addition of supplemental iron. 4-POBN-CH(CH3)OH was stable in the presence of a neutrophil-derived superoxide flux. Hydroxyl radical formation was inhibited by treatment with superoxide dismutase, catalase, and azide. Treatment with a series of transition metal chelators did not appreciably alter 4-POBN-CH(CH3)OH, which suggested that hydroxyl radical generation was mediated by a mechanism independent of the transition metal- catalyzed Haber-Weiss reaction. Kinetic differences between transition metal- dependent and -independent mechanisms of hydroxyl radical generation by stimulated neutrophils were demonstrated by a greater rate of 4-POBN- CH(CH3)OH accumulation in the presence of supplemental iron. Detection of hydroxyl radical from stimulated monocyte-derived macrophages, which lack myeloperoxidase, required the addition of supplemental iron. The addition of purified myeloperoxidase to an enzymatic superoxide generating system resulted in the detection of hydroxyl radical that was dependent upon the presence of chloride and was inhibited by superoxide dismutase, catalase, and azide. These findings implicated the reaction of hypochlorous acid and superoxide to produce hydroxyl radical. 4-POBN-CH(CH3)OH was not observed upon stimulation of myeloperoxidase-deficient neutrophils, whereas addition of myeloperoxidase to the reaction mixture resulted in the detection of hydroxyl radical. These results support the ability of human neutrophils and monocytes to generate hydroxyl radical through a myeloperoxidase-dependent mechanism.
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M3 - Article
C2 - 1314821
AN - SCOPUS:0026644780
VL - 267
SP - 8307
EP - 8312
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 12
ER -