Superoxide production of human polymorphonuclear leukocytes stimulated by leukotriene B 4

Abstract

Leukotriene B 4 stimulated a transient production of superoxide anions (O − 2) by human polymorphonuclear leukocytes which continued for only about 1 min. The production was dependent on Ca 2+ in the suspending medium and no production was observed without the addition of calcium. The concentrations of leukotriene B 4 and calcium for the half-maximal production were about 1 μM and 200 μM, respectively. 8-( N, N,-Diethylamino)-octyl-3,4,5-trimethoxybenzoate (TMB-8), an intracellular calcium antagonist, did not inhibit the O − 2 production stimulated by leukotriene B 4 in the presence of calcium, while N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), a calmodulin inhibitor, did. When leukotriene B 4 was added to the cells treated with cytochalasin B, the production of O − 2 was biphasic: an initial rapid phase, followed by a slow one. The slow phase was also dependent on Ca 2+ concentrations but it could be induced even without the addition of Ca 2+ to the medium. The cells treated with both cytochalasin B and TMB-8 in Ca 2+-free medium showed a negligible production of superoxide on addition of leukotriene B 4, but the production appeared upon addition of CaCl 2. These findings suggest that the superoxide production stimulated by leukotriene B 4 is associated with the influx of Ca 2+.