Fiedler J, Wheelan P, Henson P M, Murphy R C
Department of Pediatrics, Division of Basic Sciences, National Jewish Medical and Research Center, Denver, Colorado, USA.
J Pharmacol Exp Ther. 1998 Oct;287(1):150-6.
The effect of exogenous leukotriene B4 (LTB4) on opsonized zymosan-stimulated human neutrophil formation of 5-lipoxygenase products and arachidonic acid release was directly assessed using reverse-phase HPLC/tandem mass spectrometric methods for quantitation. Stable isotopically labeled LTB4, [1,2-13C2]LTB4, caused a dose-dependent inhibition of LTB4 production in isolated human neutrophils with significant inhibition (60 +/- 7% of control levels) when 0.12 nM [13C2]LTB4 was present. Production of 5-hydroxy-6,8,11,14-eicosatetraenoic acid and release of free arachidonic acid were also dose-dependently inhibited by exogenous LTB4. Metabolites of LTB4, 20-hydroxy-LTB4 and 3(S)-hydroxy-LTB4, also significantly reduced LTB4 production to levels as low as 10 +/- 6% and 10 +/- 7% of control levels, respectively, when present exogenously at 10 nM. Exogenous 5-hydroxy-6,8,11,14-eicosatetraenoic acid at concentrations as high as 10 nM produced no significant reduction in LTB4 biosynthesis during zymosan-stimulated human neutrophil production of LTB4. The inhibitory effect of LTB4 could be partially reversed by the LTB4 receptor antagonist U 75302. Furthermore, an alternative stimulus, N-formyl-methionyl-leucyl-phenylalanine (100 nM), did not inhibit the production of LTB4 in opsonized zymosan-stimulated human neutrophils. These results suggest that activation of the LTB4 receptor on the human neutrophil during phagocytosis limits the ultimate biosynthesis of LTB4. This autocrine effect is opposite to that observed when neutrophils have much of the signal transduction pathways bypassed when stimulated with calcium ionophore A23187 or treated with exogenous free arachidonic acid.
使用反相高效液相色谱/串联质谱法定量，直接评估外源性白三烯B4（LTB4）对调理酵母聚糖刺激的人中性粒细胞5-脂氧合酶产物形成和花生四烯酸释放的影响。稳定同位素标记的LTB4，即[1,2-13C2]LTB4，在分离的人中性粒细胞中引起LTB4产生的剂量依赖性抑制，当存在0.12 nM [13C2]LTB4时，抑制作用显著（为对照水平的60±7%）。外源性LTB4也剂量依赖性地抑制5-羟基-6,8,11,14-二十碳四烯酸的产生和游离花生四烯酸的释放。当外源性存在10 nM时，LTB4的代谢产物20-羟基-LTB4和3(S)-羟基-LTB4也分别将LTB4的产生显著降低至对照水平的10±6%和10±7%。浓度高达10 nM的外源性5-羟基-6,8,11,14-二十碳四烯酸在酵母聚糖刺激的人中性粒细胞产生LTB4的过程中，对LTB4生物合成没有显著降低作用。LTB4受体拮抗剂U 75302可部分逆转LTB4的抑制作用。此外，另一种刺激物N-甲酰甲硫氨酰-亮氨酰-苯丙氨酸（100 nM）在调理酵母聚糖刺激的人中性粒细胞中不抑制LTB4的产生。这些结果表明，吞噬过程中人类中性粒细胞上LTB4受体的激活限制了LTB4的最终生物合成。这种自分泌效应与用钙离子载体A23187刺激或用外源性游离花生四烯酸处理时中性粒细胞许多信号转导途径被绕过的情况相反。
