Enhancement by staurosporine of platelet-activating factor formation in N-formyl peptide-challenged human neutrophils is mediated by intracellular platelet-activating factor binding sites.

Staurosporine potentiates the formation of platelet-activating factor (PAF) and causes a sustained elevation of intracellular Ca2+ (Ca2+]i). WEB 2086, a specific PAF-receptor antagonist, inhibits both potentiation of PAF formation and elevation of Ca2+]i by 78% and 65%, respectively. Moreover, the PAF produced by FMLP and/or Staurosporine was completely retained in the cell. This suggests that the effect of staurosporine in FMLP-stimulated neutrophils may be mediated by the action of endogenously produced PAF, which in turn leads to an increase in Ca2+]i and PAF formation. We conclude that PAF is the major product of human neutrophils which reacts via specific intracellular PAF binding sites to stimulate the phospholipase A2, and its synthesis is under control of a staurosporine-sensitive protein kinase.