Neutrophil degranulation inhibits potential hydroxyl-radical formation. Relative impact of myeloperoxidase and lactoferrin release on hydroxyl-radical production by iron-supplemented neutrophils assessed by spin-trapping techniques.
Hydroxyl radical (.OH) formation by neutrophils in vitro requires exogenous iron. Two recent studies [Britigan, Rosen, Thompson, Chai & Cohen (1986) J. Biol. Chem. 261, 17026-17032; Winterbourn (1987) J. Clin. Invest. 78, 545-550] both reported that neutrophil degranulation could potentially inhibit the formation of .OH, but differed in their conclusions as to the responsible factor, myeloperoxidase (MPO) or lactoferrin (LF). By using a previously developed spin-trapping system which allows specific on-line detection of superoxide anion (O2-) and .OH production, the impact of MPO and LF release on neutrophil .OH production was compared. When iron-diethylenetriaminepenta-acetic acid-supplemented neutrophils were stimulated with phorbol myristate acetate or opsonized zymosan, .OH formation occurred, but terminated prematurely in spite of continued O2- generation. Inhibition of MPO by azide increased the magnitude, but not the duration, of .OH formation. No azide effect was noted when MPO-deficient neutrophils were used. Anti-LF antibody increased both the magnitude and duration of .OH generation. Pretreatment of neutrophils with cytochalasin B to prevent phagosome formation did not alter the relative impact of azide or anti-LF on neutrophil .OH production. An effect of azide or anti-LF on spin-trapped-adduct stability was eliminated as a confounding factor. These data indicate that neutrophils possess two mechanisms for limiting .OH production. Implications for neutrophil-derived oxidant damage are discussed.
Britigan
B E
BE
Department of Medicine, Veterans Administration Medical Center, Iowa City, IA.
Hassett
D J
DJ
Rosen
G M
GM
Hamill
D R
DR
Cohen
M S
MS
D000906:Antibodies; D001386:Azides / Q000494:pharmacology; D015550:Cell Degranulation; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006801:Humans; D006878:Hydroxides / Q000097:blood*; D017665:Hydroxyl Radical; D066298:In Vitro Techniques; D007501:Iron / Q000494:pharmacology*; D007781:Lactoferrin / Q000097:blood*; D007782:Lactoglobulins / Q000097:blood*; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D010101:Oxygen Consumption; D009195:Peroxidase / Q000097:blood*; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000097:blood; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015054:Zymosan / Q000494:pharmacology
D000906:Antibodies; D001386:Azides; D005609:Free Radicals; D006878:Hydroxides; D007782:Lactoglobulins; D013481:Superoxides; D017665:Hydroxyl Radical; D015054:Zymosan; D007501:Iron; D009195:Peroxidase; D013482:Superoxide Dismutase; D007781:Lactoferrin; D013755:Tetradecanoylphorbol Acetate