The human CD8 coreceptor effects cytotoxic T cell activation and antigen sensitivity primarily by mediating complete phosphorylation of the T cell receptor ζ chain
The human CD8 coreceptor effects cytotoxic T cell activation and antigen sensitivity primarily by mediating complete phosphorylation of the T cell receptor ζ chain
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DOI：
10.1074/jbc.m102498200
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发表时间：
2001-08-31
影响因子：
4.8
通讯作者：
Sewell, AK
中科院分区：
文献类型：
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作者：
Purbhoo, MA;Boulter, JM;Sewell, AK
细胞毒性 T 淋巴细胞 (CTL) 对抗原的识别是由 T 细胞受体及其 CD8 辅助受体与肽主要组织相容性复合物 (pMHC) I 类分子的相互作用决定的。我们使用旨在减少或消除 CD8/pMHC 相互作用的 MHC I 类突变来检查这些受体在人类 CTL 激活中的相对作用。我们使用表面等离子共振来确定 HLA A2 的 α3 环的点突变会消除 CD8/pMHC 相互作用，而不影响 T 细胞受体/pMHC 相互作用的亲和力。表达不与 CD8 结合的 HLA A2 的抗原呈递细胞在任何肽浓度下都无法激活 CTL。表达 HLA A2 的靶标与正常、废除或减少的 CD8/pMHC 相互作用的 CTL 激活比较表明，CD8/pMHC 相互作用增强了对抗原的敏感性。我们确定辅助受体依赖性的生化基础是 CD3 zeta 链 23-kDa 磷酸形式的激活。此外，我们还生产突变型 MHC I 类多聚体，可特异性染色但不激活 CTL。当 pMHC 多聚体用于对抗原特异性 CD8+ 淋巴细胞进行表型分析时，这些试剂可能有助于避免细胞内过程中与激活相关的不良扰动。
Recognition of antigen by cytotoxic T lymphocytes (CTL) is determined by interaction of both the T cell receptor and its CD8 coreceptor with peptide-major histocompatibility complex (pMHC) class I molecules. We examine the relative roles of these receptors in the activation of human CTL using mutations in MHC class I designed to diminish or abrogate the CD8/pMHC interaction. We use surface plasmon resonance to determine that point mutation of the alpha3 loop of HLA A2 abrogates the CD8/pMHC interaction without affecting the affinity of the T cell receptor/pMHC interaction. Antigen-presenting cells expressing HLA A2 which does not bind to CD8 fail to activate CTL at any peptide concentration. Comparison of CTL activation by targets expressing HLA A2 with normal, abrogated, or diminished CD8/pMHC interaction show that the CD8/pMHC interaction enhances sensitivity to antigen. We determine that the biochemical basis for coreceptor dependence is the activation of the 23-kDa phosphoform of the CD3 zeta chain. In addition, we produce mutant MHC class I multimers that specifically stain but do not activate CTL. These reagents may prove useful in circumventing undesirable activation-related perturbation of intracellular processes when pMHC multimers are used to phenotype antigen-specific CD8+ lymphocytes.