Activation of nitric oxide release and oxidative metabolism by leukotrienes B-4, C-4, and D-4 in human polymorphonuclear leukocytes

Because arachidonate metabolites are potent mediators of inflammation, we h ave studied the effects of leukotriene B-4 (LTB4) and the cysteinyl leukotr ienes C-4 and D-4 (LTC4 and LTD4) on the release of nitric oxide (NO), in v itro, by human polymorphonuclear granulocytes (PMN). Two independent and hi ghly sensitive real-time methods were used for these studies, ie, the NO-de pendent oxidation of oxyhemoglobin (HbO(2)) to methemoglobin and a NO-sensi tive microelectrode. When activated with LTB4, LTC4, or LTD4, but not with other lipoxygenase products such as 5S-HETE, 5-oxo-ETE or 5S,12S-diHETE, PM N produced NO in a stimulus- and concentration-dependent manner. The rank o rder of potency was LTB4 = LTC4 > LTD4, corresponding to 232 +/- 50 pmol of NO/10(6) PMN for 100 nmol/L LTB4 after 30 minutes. The kinetic properties of the responses were similar for all three leukotrienes with a maximum res ponse at 13 +/- 3 minutes. Cysteinyl leukotriene and LTB4 antagonists inhib ited the agonist-induced NO production by 70%, and treatment with Bordetell a pertussis toxin, or chelation of cytosolic Ca2+, [Ca2+](i), also efficien tly inhibited this response. In contrast, treatment of PMN with cytochalasi n B (5 mu g/mL) enhanced the LTB4-induced NO formation by 86%. Thus, this i s the first demonstration that the cysteinyl leukotrienes LTC4 and LTD4, as well as LTB4 activate NO release from human PMN by surface receptor, G-pro tein and [Ca2+](i)-dependent mechanisms. This effect differs from activatio n of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, for w hich only LTB4 is an activator. (C) 1999 by The American Society of Hematol ogy.