Activation of monocytes by interferon-gamma has no effect on the level or affinity of the nicotinamide adenine dinucleotide-phosphate oxidase and on agonist-dependent superoxide formation.
Human monocytes purified by elutriation were cultured for 3 d in Teflon bags with or without human recombinant interferon-gamma (rIFN gamma). The cells were then collected and used in suspension to determine the rate of stimulus-dependent superoxide or hydrogen peroxide formation as a measure of the NADPH-oxidase. The treatment with IFN gamma increased this rate two- to threefold when phorbol myristate acetate (PMA) was used as the stimulus. By contrast, no IFN gamma-dependent increase in superoxide production was observed when the cells were stimulated with different concentrations of the receptor agonist N-formyl-methionyl-leucyl-phenylalanine (f-Met-Leu-Phe) alone or in combination with another receptor agonist, platelet-activating factor (PAF). At optimum concentrations, f-Met-Leu-Phe elicited rates of superoxide formation that could not be exceeded under other stimulatory conditions including PMA after treatment with IFN gamma. It thus appears that f-Met-Leu-Phe can lead to maximum activation of the NADPH-oxidase, and that this response is not influenced by IFN gamma. Treatment with IFN gamma also failed to affect the affinity of PMA- or f-Met-Leu-Phe-stimulated oxidase for NADPH, the Km values being 30 to 40 microM under all conditions. IFN gamma did not alter the cellular levels of cytochrome b558, as measured by low-temperature spectroscopy, and protein kinase C, as measured by [3H]phorbol dibutyrate binding, and did not appreciably influence the stimulus-dependent increase of cytosolic free calcium. These results indicate that activation of human mononuclear phagocytes by IFN gamma does not affect the level and the kinetic properties of NADPH-oxidase or its activation by receptor agonists. They confirm, however, that IFN gamma enhances the respiratory burst response to PMA.
Thelen
M
M
Theodor-Kocher Institut, University of Bern, Switzerland.
Wolf
M
M
Baggiolini
M
M
D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003573:Cytochrome b Group / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology*; D007700:Kinetics; D009000:Monocytes / Q000201:enzymology / Q000378:metabolism*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D019255:NADPH Oxidases; D010101:Oxygen Consumption; D010972:Platelet Activating Factor / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D003573:Cytochrome b Group; D010972:Platelet Activating Factor; D011994:Recombinant Proteins; D013481:Superoxides; D009249:NADP; D009240:N-Formylmethionine Leucyl-Phenylalanine; D007371:Interferon-gamma; D006861:Hydrogen Peroxide; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium