Cytokines regulate membrane-bound leukocyte elastase on neutrophils: a novel mechanism for effector activity.
Membrane-bound leukocyte elastase activity on neutrophils may have potent proinflammatory effects. Herein, we report the effects of tumor necrosis factor-alpha (TNF-alpha), platelet-activating factor (PAF), N-formyl-leucyl-methionyl-phenylalanine (fMLP), and interleukin-8 (IL-8) on membrane-bound elastase expression. TNF-alpha or PAF alone induced only approximately two- to threefold increases in membrane-bound elastase but exhibited marked dose- and time-dependent priming effects for subsequent stimulation with fMLP or IL-8 (up to 20-fold increases in membrane-bound human leukocyte elastase compared with unstimulated cells). Optimally PAF-primed and fMLP-stimulated cells expressed 1.105 +/- 0.25 (SD) x 10(-17) mol [6.65 +/- 1.51 (SD) x 10(6) molecules] membrane-bound elastase activity/cell or approximately 12% of the content of unstimulated cells. Elastase binds to the cell surface by a charge-dependent mechanism since 1) incubation of cells with cationic molecules abrogated agonist-induced upregulation of membrane-bound elastase and 2) elastase was progressively eluted from the cell surface by solutions with increasing ionic strength. Thus interactions between proinflammatory mediators strikingly upregulate membrane-bound elastase on neutrophils, which may promote inflammatory responses and/or contribute to tissue injury.
Owen
C A
CA
Department of Medicine, University of Utah Health Sciences Center, Salt Lake City 84132, USA.
Campbell
M A
MA
Boukedes
S S
SS
Campbell
E J
EJ
D006801:Humans; D007249:Inflammation / Q000201:enzymology; D016209:Interleukin-8 / Q000494:pharmacology; D007477:Ions; D019272:Leukocyte Elastase / Q000378:metabolism*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000201:enzymology*; D010972:Platelet Activating Factor / Q000008:administration & dosage; D013499:Surface Properties; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage; D015854:Up-Regulation
D016209:Interleukin-8; D007477:Ions; D010972:Platelet Activating Factor; D014409:Tumor Necrosis Factor-alpha; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019272:Leukocyte Elastase