Formation of polymorphonuclear leukocyte elastase: alpha 1 proteinase inhibitor complex and a alpha (1-21) fibrinopeptide in human blood stimulated with the calcium ionophore A23187. a model to characterize inhibitors of polymorphonuclear leukocyte elastase

Pacholok, S.G.; Davies, P.; Dorn, C.; Finke, P.; Hanlon, W.A.; Mumford, R.A.; Humes, J.L.

Biochemical Pharmacology 49(10): 1513-1520


ISSN/ISBN: 0006-2952
PMID: 7763294
DOI: 10.1016/0006-2952(95)00031-t
Accession: 043147890

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Incubation of human blood with the secretagogue A23187 resulted in the formation of increased plasma concentrations of polymorphonuclear leukocyte (PMN) elastase: alpha 1 proteinase inhibitor (PMNE:alpha 1 PI) complex as well as A alpha(1-21) fibrinopeptide [A alpha(1-21)]. The formation of these species was both time and A23187 concentration dependent. Using a sandwich ELISA and a radioimmunoassay, we determined the comparative potencies of several compounds to inhibit the formation of PMNE: alpha 1 PI complexes and A alpha(1-21), respectively. L-658,758, a substituted cephalosporin, essentially irreversible elastase inhibitor, inhibited the formation of PMNE: alpha 1 PI and A alpha(1-21) with IC50 values of 38 and 15 microM, respectively. L-683,845, a monocyclic beta-lactam, was much more potent against isolated PMNE than L-658,758. However in this system it was approximately equivalent to L-658,758 with an IC50 of 15 microM against both species. ICI-200,880, a competitive slow-binding elastase inhibitor, was significantly less potent to inhibit A alpha(1-21), having an IC50 of 75 microM, while Declaben, a reversible noncompetitive inhibitor, was inactive at concentrations as great as 200 microM. We propose that evaluating inhibitors in the complex milieu of blood will provide a useful method to predict their therapeutic potential in vivo.