RTX toxins recognize a beta 2 integrin on the surface of human target cells
RTX toxins recognize a beta 2 integrin on the surface of human target cells
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DOI：
10.1074/jbc.272.48.30463
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发表时间：
1997-11-28
影响因子：
4.8
通讯作者：
Billings, PC
中科院分区：
文献类型：
--
作者：
Lally, ET;Kieba, IR;Billings, PC
伴生放线杆菌白毒素和大肠杆菌α-溶血素是RTX毒素，可杀死人类免疫细胞。我们已经获得了一种针对毒素敏感的HL60细胞上存在的细胞表面分子的单抗(295)，该抗体可以抑制两种RTX毒素的细胞溶解。用该单抗对洗涤剂增溶的靶细胞膜进行免疫亲和纯化，得到两条分子量约为100和170 kDa的多肽链。经显微测序证实，这两种蛋白与淋巴细胞功能相关抗原1(LFA-1)β2整合素的两个亚基CD11a和CD18完全同源。抗CD11a和CD18单抗也能抑制RTX毒素介导的细胞溶解。直接结合实验证明，固定化RTX能够结合存在于人HL60靶细胞的特异性裂解液中的LFA-1异源二聚体。将CD11a和CD18整合素基因导入对两种毒素均不敏感的K562细胞系，获得对这两种毒素均敏感的LFA-1表达细胞KL/4。这些实验确定LFA-1是一种细胞表面受体，介导了这类致孔毒素家族成员的毒性。
Actinobacillus actinomycetemcomitans leukotoxin and Escherichia coli alpha-hemolysin are RTX toxins that kill human immune cells. We have obtained a monoclonal antibody (295) to a cell surface molecule present on toxin-sensitive HL60 cells that can inhibit cytolysis by both RTX toxins. Utilization of this monoclonal antibody for immunoaffinity purification of detergent-solubilized target cell membranes yielded two polypeptide chains of approximate molecular masses of 100 and 170 kDa. Microsequencing of tryptic peptides from the two proteins showed complete homology with CD11a and CD18, the two subunits of the beta 2 integrin, lymphocyte function-associated antigen 1 (LFA-1). Anti-CD11a and CD18 monoclonal antibodies also inhibited RTX toxin-mediated cytolysis. Direct binding experiments demonstrated the ability of an immobilized RTX to bind LFA-1 heterodimers present in a deter gent lysate of human HL60 target cells. Transfection of CD11a and CD18 integrin genes into a cell line (K562) that is not sensitive to either RTX toxin resulted in LFA-1 expressing cells, KL/4, that were sensitive to both toxins. These experiments identify LFA-1 as a cell surface recep- tor that mediates toxicity of members of this family of pore-forming toxins.