Tesh V L, Duncan R L, Morrison D C
J Immunol. 1986 Aug 15;137(4):1329-35.
We have examined the killing of E. coli and kinetics of lipopolysaccharide (LPS) release after the exposure of the bacteria to normal human serum (NHS) and sera deficient in complement components, or with inactivated complement components. LPS of the galactose epimerase-deficient strain E. coli J5 were specifically radiolabeled by growing the bacteria in a medium containing [3H]galactose. Exposure of the washed bacteria to NHS resulted in a significant reduction (greater than 99%) in viability within 15 min and the concomitant release of radiolabeled LPS. However, maximal release of LPS was consistently 30% of the total radiolabel incorporated into the LPS molecules. The amount of tritium-labeled LPS released was shown to be directly proportional to the concentration of bacteria exposed to NHS, suggesting that release of LPS was not limited by the availability of some critical serum component(s). The consumption of complement in NHS by incubation with E. coli was demonstrated by decreased alternative and classical pathway-specific hemolytic activity. The use of Factor D-depleted and VEM-treated human sera demonstrated that, with these bacteria, both the alternative and classical pathways of complement contribute to bacterial killing and release of LPS. It is noteworthy that, in VEM-treated and Factor D-depleted sera, the rate of killing and the kinetics of LPS release were somewhat slower as compared to control serum. Bacterial killing in C7-depleted and C9-deficient human sera was minimal. Neither killing nor LPS release occurred in heat-inactivated (56 degrees C, 30 min) human serum. The amount of [3H]LPS released by C9-deficient serum was qualitatively similar to the amount released by the action of NHS. Tritium-labeled LPS was not released in C7-depleted serum. These data indicate that bacterial killing can be dissociated from LPS release, and suggest that, whereas LPS release may be necessary for the bactericidal effects of serum complement, it is probably not sufficient to effect killing. Furthermore, a significant fraction of LPS can be removed from the outer membrane of the bacteria without an apparent affect on viability.
我们研究了将大肠杆菌暴露于正常人血清（NHS）、缺乏补体成分的血清或补体成分已灭活的血清后，大肠杆菌的杀灭情况以及脂多糖（LPS）释放的动力学。通过在含有[3H]半乳糖的培养基中培养，对缺乏半乳糖差向异构酶的大肠杆菌J5菌株的LPS进行特异性放射性标记。将洗涤后的细菌暴露于NHS中，15分钟内其活力显著降低（超过99%），同时放射性标记的LPS释放出来。然而，LPS的最大释放量始终为掺入LPS分子的总放射性标记的30%。结果表明，释放的氚标记LPS的量与暴露于NHS的细菌浓度成正比，这表明LPS的释放不受某些关键血清成分可用性的限制。通过替代途径和经典途径特异性溶血活性的降低，证明了大肠杆菌与NHS孵育会消耗补体。使用缺乏因子D和经VEM处理的人血清表明，对于这些细菌，补体的替代途径和经典途径均有助于细菌的杀灭和LPS的释放。值得注意的是，与对照血清相比，在经VEM处理和缺乏因子D的血清中，杀灭速率和LPS释放的动力学稍慢。在缺乏C7和缺乏C9的人血清中，细菌杀灭作用极小。热灭活（56℃，30分钟）的人血清中既不发生杀灭也不发生LPS释放。缺乏C9的血清释放的[3H]LPS的量在质量上与NHS作用释放的量相似。在缺乏C7的血清中不释放氚标记的LPS。这些数据表明细菌杀灭可与LPS释放分离，并表明，虽然LPS释放可能是血清补体杀菌作用所必需的，但可能不足以实现杀灭。此外，相当一部分LPS可从细菌外膜去除，而对活力无明显影响。
