5804 INDUCIBLE BINDING OF BlOACTlVE CATHEPSIN G TO NEUTROPHILS
نویسنده
چکیده
Catalytically active cathepsin G that is bound to the cell surface of human neutrophils may play a variety of roles in normal neutrophil biology and in pathobiology associated with inflammation. In this study, we describe expression of neutrophil cell surface-bound cathepsin G in response to TNF-a and platelet-activating factor (PAF) under conditions in which minimal free release of cathepsin C is detected. TNF-a and PAF alone induced modest (two-to threefold) increases in cell surface-bound cathepsin C, but exhibited a marked dose-and time-dependent priming effect for subsequent chemoattractant-induced responses (up to 15-to 25-fold increases in cell surface expression). When optimally primed (TNF-a, 100 U/ml, or PAF, lo-' M), neutrophils expressed five-to sixfold more cell surface-bound cathepsin G , in comparison with cells exposed to FMLP alone. Priming responses were more rapid with PAF (15 s to 5 min) than with TNF-a (1 to 60 min). Optimally primed and FMLP-stimulated neutrophils express-1 60 ng of catalytically active cathepsin C per 1 O6 cells, which represents-1 1 YO of the cellular content of unstimulated cells. Cathepsin G binds to the cell surface by a charge-dependent mechanism since: 1) incubation of
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