Release of leukotriene B4 from human neutrophils and its relationship to degranulation induced by N-formyl-methionyl-leucyl-phenylalanine, serum-treated zymosan and the ionophore A23187

Abstract

The release of leukotriene B4 (LTB4) from human neutrophils and its relationship to degranulation induced by the divalent cation ionophore A23187, serum-treated zymosan (STZ), N-formyl-methionyl-leucyl-phenylalanine (FMLP) and arachidonic acid (AA) have been studied. Greatest release of LTB4, measured by specific radioimmunoassay, occurred in response to A23187 (5-10 ng/10(6) cells); lower concentrations were obtained after incubation with STZ (0.2-0.8 ng/10(6) cells) and AA (0.3-2.6 ng/10(6) cells) and low (0.02 ng/10(6) cells) or not detectable amounts from cells incubated with FMLP. Release of LTB4 induced by STZ, FMLP and submaximal concentrations of A23187 was potentiated by simultaneous addition of AA. Lower amounts (0.06-0.3 ng/10(6) cells) of thromboxane B2 (TXB2) were also released by these stimuli, however this release of TXB2 was not potentiated by exogenous AA. The secretion of beta-glucuronidase induced by A23187, STZ and FMLP was not quantitatively related to release of LTB4 or TXB2 and was not potentiated by exogenous AA. Furthermore, FMLP induced degranulation was cytochalasin B (Cyt B)-dependent, whereas LTB4 release in response to this stimulus was only marginally increased by pretreatment of the cells with Cyt B. These data indicate that LTB4 does not mediate degranulation induced by these stimuli.