title: A peroxidase-independent method for the quantitation of extracellular hydrogen peroxide generated by activated phagocytes in vitro.
abstract: A peroxidase-independent method for the determination of phagocyte-derived hydrogen peroxide in vitro is described. The method is based on the catalase-inhibitable oxidation of added cysteine. Human blood neutrophils (1 x 10(6)/ml) were coincubated with the myeloperoxidase (MPO) inhibitor, sodium azide (10 micrograms/ml), for 30 min at 37 degrees C followed by addition of phorbol 12-myristate 13-acetate (PMA, 10 ng/ml), a potent activator of membrane-associated oxidative metabolism. After incubation at 37 degrees C the cells were removed and the supernatants aliquoted and incubated with and without catalase (500 U/ml) for 10 min at room temperature followed by addition of cysteine (50 microM). Thereafter the catalase-inhibitable, H2O2-mediated oxidation of added cysteine was assayed spectrophotometrically following the addition of the thiol-reactive agent 5,5'-dithiobis-(2-nitrobenzoic acid), and the H2O2 concentration determined using a standard curve constructed from difference data based on the oxidation of cysteine by H2O2 (0-200 nmol). The average amount of H2O2 produced by 10(6) PMA-activated neutrophils was 47 +/- 7 nmol/30 min. This sensitive assay procedure is likely to be particularly useful for investigating the effects of pharmacological agents and anti-oxidant nutrients on H2O2 production by activated phagocytes, since these agents are generally unsuited for use in peroxidase-based assays.
authors.affiliation: Department of Immunology, University of Pretoria, South Africa.
authors.forename: R
authors.initials: R
authors.lastname: Anderson
mesh_terms: D001386:Azides / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism; D003545:Cysteine; D004228:Dithionitrobenzoic Acid; D006801:Humans; D006861:Hydrogen Peroxide / Q000032:analysis*; D009504:Neutrophils / Q000378:metabolism; D009195:Peroxidase / Q000037:antagonists & inhibitors; D010544:Peroxidases; D010586:Phagocytes / Q000378:metabolism*; D019810:Sodium Azide; D013053:Spectrophotometry / Q000379:methods; D013481:Superoxides / Q000032:analysis
chemical_list: D001386:Azides; D013481:Superoxides; D019810:Sodium Azide; D004228:Dithionitrobenzoic Acid; D006861:Hydrogen Peroxide; D010544:Peroxidases; D002374:Catalase; D009195:Peroxidase; D003545:Cysteine