Antigen contacts by Ni-reactive TCR:: typical αβ chain cooperation versus α chain-dominated specificity
Antigen contacts by Ni-reactive TCR:: typical αβ chain cooperation versus α chain-dominated specificity
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DOI：
10.1093/intimm/12.12.1723
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发表时间：
2000-12-01
影响因子：
4.4
通讯作者：
Moulon, C
中科院分区：
文献类型：
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作者：
Vollmer, J;Weltzien, HU;Moulon, C
VB 17（+）TCR在来自高度Hi致敏患者的Ni驱动的T细胞培养物中占主导地位。通过转染CD 4（+）、VB 17（+）、Ni特异性人T细胞克隆的TCR，通过TCR定点突变和不同TCR间α、β链的结合，研究了它们与Ni-MHC的接触。所有三种TCR在其CDR 3-β序列中均表现出N-核苷酸决定的Arg-Asp基序。其中两种TCR特异性限制于HLA-DR 13，而第三种TCR接受多种HLA-DR等位基因。DR 13限制性TCR的高度相似的α或β链可互换而不丧失特异性，但不耐受其他TCR的α或β链。其Arg-Asp基序的突变揭示了在将Asp交换为Glu或Ala以及将Arg交换为Ala时反应性的丧失，但Arg不交换为Lys或Hi结合His。链位置51的突变也破坏了反应性，该位置被认为是MHC的一般接触位点。因此，在这两种TCR中，Arg-Asp基序显然参与了HI-MHC复合物的接触，并且需要α和β链之间的密切合作。相反，第三TCR在链位置51或其β链Arg-Asp基序突变后保留Hi反应性，这反而影响DR交叉限制的模式。此外，其α链与来自其他甚至小鼠TCR的各种β链配对，而不管它们的特异性如何，保留Hi反应性以及混杂的HLA-DR限制。α链在定义特异性方面的这种优势表明个体TCR的H1相互作用的根本差异，并意味着β链相似性可能不一定由抗原选择引起。
VB17(+) TCR dominate in Ni-driven T cell cultures from highly Hi-sensitized patients. Using transfection of TCR from three CD4(+), VB17(+), Ni-specific human T cell clones, we studied their Ni-MHC contacts by site-directed TCR mutation and combination of alpha and beta chains between different TCR. All three TCR exhibited N-nucleotide-determined Arg-Asp motifs in their CDR3-beta sequences. Two of them were specifically restricted to HLA-DR13, while the third one accepted a variety of HLA-DR alleles, The highly similar alpha or beta chains of the DR13-restricted TCR were interchangable without loss of specificity, but alpha or beta chains of other TCR were not tolerated. Mutations of their Arg-Asp motif revealed loss of reactivity upon exchanging Asp for Glu or Ala and of Arg for Ala but not of Arg for Lys or the Hi binding His. Reactivity was also destroyed by mutation of a chain position 51, proposed as a general contact site for MHC, Hence, in these two TCR the Arg-Asp motif is clearly involved in contacting HI-MHC complexes, and close cooperation between alpha and beta chain is required. In contrast, the third TCR retained Hi reactivity upon mutation of a chain position 51 or of its beta chain Arg-Asp motif, which rather affected the pattern of DR cross-restriction, Moreover, its alpha chain paired with various beta chains from other, even mouse TCR, irrespective of their specificity, retaining Hi reactivity as well as promiscuous HLA-DR restriction. This preponderance of an a chain in defining specificity indicates fundamental differences in Hi interactions of individual TCR and implies that beta chain similarities may not necessarily result from antigen selection.