Leukotriene B4 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 Ca2+ in the suspending medium and no production was observed without the addition of calcium. The concentrations of leukotriene B4 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 B4 in the presence of calcium, while N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), a calmodulin inhibitor, did. When leukotriene B4 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 Ca2+ concentrations but it could be induced even without the addition of Ca2+ to the medium. The cells treated with both cytochalasin B and TMB-8 in Ca2+-free medium showed a negligible production of superoxide on addition of leukotriene B4, but the production appeared upon addition of CaCl2. These findings suggest that the superoxide production stimulated by leukotriene B4 is associated with the influx of Ca2+.
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