Polymorphonuclear leukocyte-dependent modulation of platelet function: effect of cloricromene.

Cloricromene inhibits the activation of platelets and polymorphonuclear leukocytes (PMN) induced by specific stimuli. We report here that cloricromene caused a concentration-dependent reduction of platelet aggregation, beta-thromboglobulin (beta-TG) release and cytoplasmic Ca2+ movements induced by PMN stimulated with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), and enhanced the inhibitory action of unstimulated PMN on platelet responses to the stable endoperoxide analog U46619. These effects may be of pharmacological interest in view of the multiple interactions between platelets and leukocytes that occur in thrombotic and inflammatory diseases.