title: Serine protease inhibitors block priming of monocytes for enhanced release of superoxide.
abstract: Monocytes freshly isolated from human blood produced large amounts of superoxide when triggered by phorbol ester. After monocytes were cultured for 18-24 hr in endotoxin-free, non-adherent conditions, they produced low amounts of superoxide. Addition of lipopolysaccharide (LPS), interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), or platelet-activating factor (PAF) at the beginning of culture 'primed' the monocytes, causing them to maintain a high superoxide response for at least 96 hr. Also, in response to LPS, monocytes secreted TNF-alpha. The ability of LPS, IFN-gamma, TNF-alpha or PAF to maintain the high superoxide response was blocked by addition of inhibitors of serine proteases, either 4-(2-aminoethyl)-benzenesulphonyl fluoride (AEBSF) or 3,4-dichloroisocoumarin. AEBSF was most effective at 200 microns, and required 6 hr for maximum effect. AEBSF did not affect phorbol-triggered superoxide release by unprimed monocytes. AEBSF did not affect cell viability, nor did it interfere with the TNF-alpha secretion in response to LPS. An analogue of AEBSF that lacked ability to inhibit proteases did not affect monocyte responses. 3,4-Dichloroisocoumarin blocked priming at a low concentration, 1 microM. We conclude that activity of a monocyte serine protease is required to maintain the high superoxide response in monocytes primed with LPS, IFN-gamma, TNF-alpha, or PAF.
authors.affiliation: Dental Research Center, University of Tennessee, Memphis 38163, USA.
authors.forename: P
authors.initials: P
authors.lastname: Megyeri
authors.forename: K M
authors.initials: KM
authors.lastname: Pabst
authors.forename: M J
authors.initials: MJ
authors.lastname: Pabst
mesh_terms: D018929:Cell Culture Techniques; D003374:Coumarins / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D049934:Isocoumarins; D007700:Kinetics; D008070:Lipopolysaccharides / Q000276:immunology; D009000:Monocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology; D013450:Sulfones / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D000096926:Benzenesulfonamides
chemical_list: D003374:Coumarins; D049934:Isocoumarins; D008070:Lipopolysaccharides; D015842:Serine Proteinase Inhibitors; D013449:Sulfonamides; D013450:Sulfones; D013481:Superoxides; D014409:Tumor Necrosis Factor-alpha; C002010:4-(2-aminoethyl)benzenesulfonylfluoride; C097944:4-(2-aminoethyl)benzenesulfonamide; D000096926:Benzenesulfonamides; C046235:3,4-dichloroisocoumarin