Effects of a protein kinase C inhibitor, K-252a, on human polymorphonuclear neutrophil responsiveness

We investigated the capacity of K-252a, an inhibitor of rat brain protein kinase C (PKC), to influence polymorphonuclear neutrophil (PMN) PKC and PMN activation with chemically and structurally dissimilar agonists. K-252a inhibited PMN PKC (IC50 = 0.58 microM), and caused a concentration-dependent (0.1-10 microM) inhibition of degranulation elicited with the chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP), the lipid agonists, 5(S), 12(R)-dihydroxy-5,14-cis-8,10-trans eicosatetraenoic acid (LTB4) and acetyl-sn-glyceryl-3-phosphorylcholine (AGEPC), and phorbol 12-myristate 13-acetate. Superoxide anion (O2-) production by PMNs exposed to these stimuli as well as sn-1,2-dioctanoylglycerol (diC8) was also suppressed by K-252a. PMN PKC activity was inhibited with concentrations of K-252a which suppressed PMN responsiveness. Therefore, K-252a appears to be a useful probe for examining the role of PKC in the underlying pathway(s) of PMN activation.