CHARACTERIZATION OF MACROPHAGE SENSITIVITY AND RESISTANCE TO ANTHRAX LETHAL TOXIN
CHARACTERIZATION OF MACROPHAGE SENSITIVITY AND RESISTANCE TO ANTHRAX LETHAL TOXIN
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DOI：
10.1128/iai.61.1.245-252.1993
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发表时间：
1993-01-01
影响因子：
3.1
通讯作者：
SINGH, Y
中科院分区：
文献类型：
--
作者：
FRIEDLANDER, AM;BHATNAGAR, R;SINGH, Y
炭疽致死毒素由保护性抗原和致死因子两种蛋白组成，对巨噬细胞具有溶细胞作用。发现来自不同小鼠品系的巨噬细胞对毒素的敏感性不同。致死因子浓度为0.001杯子/毫升时，C3H小鼠巨噬细胞的敏感性是耐药A/J小鼠的10万倍。我们分析了中毒过程的各个阶段，以确定这种抗性的基础。与放射性碘化保护性抗原的直接结合研究表明，在敏感细胞和耐药细胞中，亲和性（K(d)，约0.5 nM）和每个细胞的受体数量（25,000至33,000）相同。在敏感和耐药巨噬细胞中，保护性抗原通过细胞表面蛋白酶的蛋白水解活化和随后的致死因子结合也是相同的。耐药的A/J巨噬细胞对其他毒素和一种病毒没有交叉抗性，这种病毒和致命毒素一样，需要囊泡酸化才能产生活性，这意味着耐药不是由于囊泡酸化的缺陷。当通过渗透裂解脂质体引入细胞质时，在缺乏保护性抗原的情况下，致死性因子对敏感的巨噬细胞具有细胞溶解作用，而耐药细胞则不受影响。因此，致死因子本身就具有致死毒素的毒性活性。这些结果表明，巨噬细胞耐药是由于毒素内化后一个阶段发生的缺陷。A/J巨噬细胞可能缺乏细胞质中假定的致死因子靶点，或者在细胞质或内吞囊泡中致死因子的进一步加工或激活方面存在缺陷。
Anthrax lethal toxin, which consists of two proteins, protective antigen and lethal factor, is cytolytic for macrophages. Macrophages from different mouse strains were found to vary in their sensitivities to toxin. C3H mouse macrophages lysed by lethal factor concentrations of 0.001 mug/ml were 100,000 times more sensitive than those from resistant A/J mice. We analyzed various stages of the intoxication process to determine the basis for this resistance. Direct binding studies with radioiodinated protective antigen revealed that the affinity (K(d), approximately 0.5 nM) and number of receptors per cell (25,000 to 33,000) were the same in sensitive and resistant cells. Proteolytic activation of protective antigen by a cell surface protease and subsequent binding of lethal factor were also the same in both sensitive and resistant macrophages. Resistant A/J macrophages were not cross-resistant to other toxins and a virus which, like lethal toxin, require vesicular acidification for activity, implying that resistance is not due to a defect in vesicular acidification. When introduced into the cytosol by osmotic lysis of pinosomes, lethal factor in the absence of protective antigen was cytolytic for the sensitive macrophages while resistant cells were unaffected. Thus, lethal factor by itself possesses the toxic activity of lethal toxin. These results suggest that macrophage resistance is due to a defect at a stage occurring after toxin internalization. A/J macrophages may lack the putative lethal factor target in the cytosol or be defective in the further processing or activation of lethal factor in the cytosol or in endocytic vesicles.