title: Biochemical, metabolic and morphological characteristics of human neutrophil activation with pepstatin A.
abstract: Pepstatin A, a chemotactic pentapeptide, elicited a concentration-dependent extracellular release of granule-associated beta-glucuronidase and lysozyme from, and generation of superoxide anion (O2-) by, cytochalasin B (CB)-treated human neutrophils. Prior exposure of neutrophils to pepstatin A before the addition of CB, suppressed, in a time-dependent fashion, the subsequent production of O2- and exocytotic response. The rate and amount of enzymes released and O2- generated by pepstatin A-activated neutrophils were significantly enhanced in the presence of extracellular calcium. Pepstatin A-elicited degranulation and O2- production were suppressed by the intracellular calcium antagonist, 8-(N,N-diethylamino)-octyl-(3, 4, 5-trimethoxy) benzoate hydrochloride (TMB-8). Granule exocytosis and O2- generation by pepstatin A-treated neutrophils were suppressed by the sulphydryl reagents, N-ethylmaleimide (NEM) and iodoacetic acid (IA), and by the glycolytic inhibitor, 2-deoxy-D-glucose (2-DG). Sodium cyanide was inactive. Preincubation of neutrophils with pepstatin A "desensitized' the cells to a subsequent exposure to pepstatin A or the chemotactic tripeptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP). Pepstatin A-induced desensitization of granule enzyme release and O2- generation appears to be stimulus-specific in that phorbol myristate acetate (PMA) was capable of eliciting normal responses from pepstatin A-pretreated cells. The morphological changes observed in pepstatin A-treated neutrophils are reminiscent of those seen in cells exposed to FMLP.
mesh_terms: D002118:Calcium / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D005089:Exocytosis / Q000187:drug effects; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005966:Glucuronidase / Q000378:metabolism; D006801:Humans; D008854:Microscopy, Electron; D009113:Muramidase / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D009842:Oligopeptides / Q000494:pharmacology*; D010436:Pepstatins / Q000494:pharmacology*; D013481:Superoxides / Q000378:metabolism
chemical_list: D009842:Oligopeptides; D010436:Pepstatins; D013481:Superoxides; C014195:Streptomyces pepsin inhibitor; D003571:Cytochalasin B; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D009113:Muramidase; D005966:Glucuronidase; D002118:Calcium; C031375:pepstatin