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

Immunology. 1995 Dec;86(4):629-35.

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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cell Culture Techniques
  • Coumarins / pharmacology
  • Dose-Response Relationship, Drug
  • Humans
  • Isocoumarins
  • 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

Substances

  • Coumarins
  • Isocoumarins
  • Lipopolysaccharides
  • Serine Proteinase Inhibitors
  • Sulfonamides
  • Sulfones
  • Tumor Necrosis Factor-alpha
  • Superoxides
  • 4-(2-aminoethyl)benzenesulfonylfluoride
  • 4-(2-aminoethyl)benzenesulfonamide
  • 3,4-dichloroisocoumarin