Davis C F, Moore F D, Rodrick M L, Fearon D T, Mannick J A
Surgery. 1987 Sep;102(3):477-84.
We attempt to elucidate the mechanisms of neutrophil (PMN) activation after burn injury. We previously reported prolonged elevations of PMN cell surface complement (C) opsonin receptor levels after burn trauma with a corresponding period of depressed PMN chemotaxis to C5a, which suggests that the C product, C5a, was responsible for PMN activation. However, a lack of direct correlation of C activation with C receptor levels soon after injury raised the possibility of a second PMN-activating substance. We therefore investigated the effect of endotoxin (LPS) on the expression of the C receptors (CR1 and CR3) by normal human PMNs. Concentrations from 0 to 50 ng/ml of LPS 026:B6 caused a dose response increase in the PMN surface expression of CR1 and CR3 as assessed by monoclonal antibody binding and indirect immunofluorescence. The relative CR1-dependent fluorescence rose from a mean of 50 to 385 and CR3 from 50 to 300. Chelation by ethylenediaminetetra acetic acid (EDTA) did not influence this dose response, thus ruling out the possibility of C activation by LPS--an inference supported by the lack of complement activation observed with these concentrations of LPS in normal serum. A similar dose response was obtained in the absence of other cell types or serum, which implies a direct effect that mimicked that of C5a. To determine the mechanism of the later, prolonged C activation after burn injury, we next examined C activation products in 22 patients with burn injuries. Elevations of plasma C3a desArg were present and persisted for 50 days. Elevations were at maximum levels on days 9 through 13 postburn (mean +/- standard error of mean [SEM], 496 +/- 47 ng/ml versus normal 113 +/- 32; p less than 0.01). These were accompanied by elevations of C4a desArg (917 +/- 154 ng/ml versus normal 424 +/- 50; p less than 0.01), which are indicative of classic pathway activation. Finally, we examined PMN function, phagocytosis and percentage killing of Staphylococcus aureus, and found PMN function to be unaltered in the 22 patients. Thus PMN activation after burn injury appears to be caused by LPS soon after injury and by C5a later after injury and affects only selected PMN functions.
我们试图阐明烧伤后中性粒细胞（PMN）激活的机制。我们之前报道过，烧伤创伤后PMN细胞表面补体（C）调理素受体水平持续升高，同时PMN对C5a的趋化性有一段相应的时间降低，这表明补体产物C5a是PMN激活的原因。然而，损伤后不久C激活与C受体水平缺乏直接相关性，这增加了存在第二种PMN激活物质的可能性。因此，我们研究了内毒素（LPS）对正常人PMN上C受体（CR1和CR3）表达的影响。用单克隆抗体结合和间接免疫荧光法评估，0至50 ng/ml的LPS 026:B6浓度导致CR1和CR3在PMN表面表达呈剂量反应性增加。CR1依赖性相对荧光从平均50升至385，CR3从50升至300。乙二胺四乙酸（EDTA）螯合不影响这种剂量反应，从而排除了LPS激活补体的可能性——在正常血清中用这些浓度的LPS未观察到补体激活这一现象支持了这一推断。在没有其他细胞类型或血清的情况下也获得了类似的剂量反应，这意味着存在一种类似于C5a的直接作用。为了确定烧伤后后期补体激活延长的机制，我们接下来检查了22例烧伤患者的补体激活产物。血浆C3a去精氨酸水平升高并持续了50天。烧伤后第9至13天升高至最高水平（平均±平均标准误差[SEM]，496±47 ng/ml，而正常为113±32；p<0.01）。这些伴随着C4a去精氨酸水平的升高（917±154 ng/ml，而正常为424±50；p<0.01），这表明经典途径被激活。最后，我们检查了PMN的功能、吞噬作用以及对金黄色葡萄球菌的杀伤百分比，发现这22例患者的PMN功能未改变。因此，烧伤后PMN激活似乎在损伤后不久由LPS引起，在损伤后期由C5a引起，并且仅影响PMN的某些特定功能。
