Characterization of effect of N-formyl-methionyl-leucyl-phenylalanine on leukotriene synthesis in human polymorphonuclear leukocytes.

Human polymorphonuclear leukocytes (PMNLs) were exposed to N-formyl-methionyl-leucyl-phenylalanine (f-Met-Leu-Phe) in the presence or absence of exogenous arachidonic acid. Analysis of incubation mixtures by high-performance liquid chromatography showed that f-Met-Leu-Phe stimulated the synthesis of 5-hydroxy-eicosatetraenoic acid (HETE) and of leukotriene B4 (LTB4) which was rapidly metabolized into 20-OH-LTB4 and 20-COOH-LTB4. The stimulatory effect of f-Met-Leu-Phe was dose and time dependent. The tripeptide showed maximum stimulatory activity at the concentration of 1 microM and after 20-30 min of incubation. Addition of arachidonic acid to the f-Met-Leu-Phe-stimulated PMNLs resulted in an increase in the synthesis of LTB4 and 5-HETE. Pretreatment of the PMNLs with cytochalasin B strongly potentiated (up to six-fold) the stimulatory effect of f-Met-Leu-Phe on 5-lipoxygenase product synthesis, whereas cytochalasin B alone or with arachidonic acid had no significant effect. The tripeptide did not increase the synthesis of platelet-derived 12-HETE, and 12-hydroxyheptadecatrienoic acid, or of PMNL-derived 15-HETE, suggesting that its action was selective for PMNL 5-lipoxygenase. The present data indicate that f-Met-Leu-Phe causes the release of arachidonic acid from cellular lipids and activates the 5-lipoxygenase.