Serine protease inhibitors block priming of monocytes for enhanced release of superoxide

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 (IF...

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Bibliographic Details
Published in:Immunology 1995-12, Vol.86 (4), p.629-635
Main Authors: Megyeri, P, Pabst, K M, Pabst, M J
Format: Article
Language:English
Subjects:
Cell Culture Techniques
Coumarins - pharmacology
Dose-Response Relationship, Drug
Humans
Kinetics
Lipopolysaccharides - immunology
Monocytes - drug effects
Monocytes - immunology
Monocytes - metabolism
Serine Proteinase Inhibitors - pharmacology
Sulfonamides - pharmacology
Sulfones - pharmacology
Superoxides - metabolism
Tumor Necrosis Factor-alpha - metabolism
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Summary: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.
ISSN:0019-2805
1365-2567