muramidase and 4-bromophenacyl-bromide

We have studied the role of arachidonic acid (AA) metabolism in the release of lysosomal enzymes (beta-glucuronidase and lysozyme) from human polymorphonuclear leukocytes (PMNs). 5,8,11,14-Eicosatetraenoic acid (ETYA), which inhibits both the cyclo-oxygenase and the lipoxygenase pathways of AA metabolism, was found to cause a dose-dependent inhibition of lysosomal enzyme release from human PMNs induced by immunological (i.e., serum-treated zymosan: Zx) and nonimmunological stimuli (i.e., formyl methionine-containing peptide and the Ca2+ ionophore A23187). In contrast, the non-steroidal anti-inflammatory drugs (indomethacin, meclofenamic acid and aspirin), which only block the cyclo-oxygenase pathway of AA metabolism, had little effect on enzyme release from PMNs induced by the same stimuli. 5,8,11-Eicosatriynoic acid (ETI), a selective inhibitor of the lipoxygenase pathway of AA metabolism, caused a dose-dependent inhibition of lysosomal enzyme release elicited by Zx, f-met peptide, and A23187. p-Bromophenacyl bromide (BPB), which inhibits the phospholipase A2 (PLA2) activity in several tissues, was found to cause a dose-dependent inhibition of lysosomal enzyme release induced by the same immunological and non-immunological stimuli. The inhibitory effect of BPB on enzyme release was irreversible and extremely rapid. It appears that activation of PLA2 and the products of the AA metabolism, generated via a lipoxygenase pathway, play an essential role in the biochemical control of human PMNs activation and secretion.

Topics: 5,8,11,14-Eicosatetraynoic Acid; Acetophenones; Anti-Inflammatory Agents; Arachidonic Acids; Fatty Acids, Unsaturated; Glucuronidase; Humans; In Vitro Techniques; Lysosomes; Muramidase; Neutrophils; Phospholipases; Phospholipases A; Phospholipases A2

Two active site inhibitors of acid proteinases were tested for their effects on human neutrophil chemotaxis and lysosomal enzyme release. Both bromphenacyl bromide (BPAB) and epoxy-p-nitrophenoxypropane (EPNP) inhibited chemotaxis and chemotaxin-induced enzyme release elicited by pepstatin and formylmethionyl peptides, which share membrane receptors, and also by zymosan-activated serum, the major active component of which (C5a) occupies a different receptor. In contrast to the previously tested acid protease inhibitor diazoacetylnorleucine methyl ester, neither BPAB nor EPNP blocked binding of [3H]fMLP to neutrophils. Thus BPAB and EPNP inhibit chemotaxin-mediated neutrophil functions, but not by interaction with the chemotaxin receptor.

Topics: Acetophenones; Acid Phosphatase; Chemotaxis, Leukocyte; Dipeptides; Epoxy Compounds; Humans; Lysosomes; Muramidase; N-Formylmethionine; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Nitrophenols; Oligopeptides; Pepstatins; Protease Inhibitors