Membrane-associated protein kinase C activity in superoxide-producing human polymorphonuclear leukocytes

Protein kinase C activity was studied in superoxide-producing human polymorphonuclear leukocytes. Using equivalent cell concentrations, superoxide production and particulate fraction-associated protein kinase C activity increased in parallel in phorbol 12-myristate 13-acetate (PMA), oleoyl-acetyl-glycerol (OAG), opsonized zymosan, and A23187-activated leukocytes. Also, an increase in particulate fraction-associated phospholipid-independent kinase activity was observed upon stimulation with these activators. In contrast, in formyl-methionyl-leucine-phenylalanine (FMLP)-activated cells the increase in superoxide production was only accompanied by an increase in particulate fraction-associated protein kinase C activity if the cells were pretreated with cytochalasin B. Purified protein kinase C activity was stimulated by OAG and PMA, whereas no stimulation was observed using A23187 or opsonized zymosan. It is suggested that the activation induced in human neutrophils by PMA, OAG, opsonized zymosan, and A23187 involves a tight membrane association of phospholipid-dependent and -independent protein kinase activity. This contrasts to FMLP-activated neutrophils, in which a membrane-bound form is only observed after pretreatment with cytochalasin B.