Effect of protein kinase C inhibitors on calcium ionophore-induced arachidonic acid mobilization in human leukocytes.

Arachidonic acid mobilization in human polymorphonuclear leukocytes stimulated with calcium ionophore A23187 was amplified by synthetic diacylglycerol and, to a much lesser extent, by phorbol ester. The effect was synergistic and dependent upon influx of calcium ions. Thin layer chromatographic analysis of phospholipids of stimulated cells revealed a loss of arachidonic acid associated with phosphatidylinositol and phosphatidylcholine. The synergistic response was unaffected by treatment of cells with two inhibitors of protein kinase C, namely, polymyxin B and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine. Moreover, both agents consistently augmented the cellular response to A23187 alone. These findings suggest that A23187-induced arachidonic acid mobilization in leukocytes is independent of protein kinase C activity.