Herrmann Jens Martin, Bernardo John, Long Heidi J, Seetoo Kurt, McMenamin Mary E, Batista Eraldo L, Van Dyke Thomas E, Simons Elizabeth R
Department of Biochemistry, Boston University School of Medicine, 80 East Concord Street, Boston, MA 02118, USA.
Infect Immun. 2007 Aug;75(8):3989-98. doi: 10.1128/IAI.00388-07. Epub 2007 May 25.
Human polymorphonuclear neutrophils (PMN) chemotax to a foreign entity. When the chemoattractants' origins are reached, specific receptors bind to the invader's surface, initiating phagocytosis, phagosome formation, and fusion with granule membranes, generating the bactericidal oxidative burst, and releasing lytic enzymes, specific peptides, and proteins. We explored the initial signaling involved in these functions by observing naïve, unprimed PMN in suspension using fluorescent indicators of cytoplasmic signals (DeltaCa(2+) and DeltapH(i)) and of bactericidal entities (oxidative species and elastase) exposed to N-formyl-methionyl-leucyl-phenylalanine (fMLP) and/or multivalent immune complexes (IC). fMLP and IC each initiate a rapid transient rise in Ca(2+), mostly from intracellular stores, simultaneously with a drop in pH(i); these are followed by a drop in Ca(2+) and a rise in pH(i), with the latter being due to a Na(+)/H(+) antiport. The impact of a second stimulation depends on the order in which stimuli are applied, on their dose, and on their nature. Provided that Ca(2+) is restored, 10(-7) M fMLP, previously shown to elicit maximal DeltaCa(2+) but no bactericidal functions, did not prevent the cells' responses with DeltaCa(2+) to a subsequent high dose of fMLP or IC; conversely, cells first exposed to 120 mug/ml IC, previously shown to elicit maximal DeltaCa(2+) and bactericidal functions, exhibited no subsequent DeltaCa(2+) or DeltapH(i) to either stimulus. While exposure to 10(-7) M fMLP, which saturates the PMN high-affinity receptor, did not elicit bactericidal release from these naïve unprimed PMN in suspension, 10(-5) M fMLP did, presumably via the low-affinity receptor, using a different Ca(2+) source.
人类多形核中性粒细胞（PMN）会向异物趋化。当到达趋化因子的来源处时，特定受体与入侵者表面结合，启动吞噬作用、吞噬体形成以及与颗粒膜融合，产生杀菌性氧化爆发，并释放溶解酶、特定肽和蛋白质。我们通过使用细胞质信号（细胞质钙离子浓度变化[DeltaCa(2+)]和细胞质pH值变化[DeltapH(i)]）以及杀菌实体（氧化物质和弹性蛋白酶）的荧光指示剂，观察悬浮状态下未经致敏的原始PMN，来探究这些功能中涉及的初始信号传导。N-甲酰甲硫氨酰-亮氨酰-苯丙氨酸（fMLP）和多价免疫复合物（IC）各自引发Ca(2+)迅速短暂升高，主要来自细胞内储存，同时pH(i)下降；随后是Ca(2+)下降和pH(i)上升，后者是由于钠氢反向转运体所致。第二次刺激的影响取决于刺激施加的顺序、剂量及其性质。前提是Ca(2+)得以恢复，先前已证明能引发最大[DeltaCa(2+)]但无杀菌功能的10^(-7) M fMLP，并不能阻止细胞对随后高剂量fMLP或IC产生的[DeltaCa(2+)]反应；相反，首先暴露于先前已证明能引发最大[DeltaCa(2+)]和杀菌功能的120微克/毫升IC的细胞，对任何一种刺激都不再表现出随后的[DeltaCa(2+)]或DeltapH(i)变化。虽然暴露于使PMN高亲和力受体饱和的10^(-7) M fMLP不会引发这些悬浮状态下未经致敏的原始PMN释放杀菌物质，但10^(-5) M fMLP会引发，推测是通过低亲和力受体，利用不同的钙离子来源。
