Inhibition of histamine secretion from rat peritoneal mast cells and rabbit leukocytes by p-bromophenacyl bromide, a phospholipase A2 inhibitor.

The present investigation was undertaken to explore the role of phospholipase A2 (PLA2) activation in histamine secretion from rabbit leukocytes and rat peritoneal mast cells (RPMC) by using p-bromophenacyl bromide (p-BPB), a potent inhibitor of PLA2. p-BPB exerted concentration dependent inhibition of allergic histamine release from RPMC and rabbit leukocytes as well as calcium ionophore A23187-stimulated histamine release from RPMC with IC50s of 36.2, 1.3 and 80.0 nM, respectively. pBPB exerted a bell-shaped (biphasic) concentration-effect (inhibition) curve on ragweed antigen-induced histamine secretion from rabbit leukocytes. The data obtained in this study suggest that PLA2 activation plays an essential role in histamine secretion from rabbit leukocytes and RPMC.