Busch D H, Pamer E G
Sections of Infectious Diseases and Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06511, USA.
J Exp Med. 1999 Feb 15;189(4):701-10. doi: 10.1084/jem.189.4.701.
T lymphocyte recognition of infected cells is mediated by T cell receptors (TCRs) interacting with their ligands, self-major histocompatibility complex (MHC) molecules complexed with pathogen-derived peptides. Serial TCR interactions with potentially small numbers of MHC/ peptide complexes on infected cells transmit signals that result in T lymphocyte expansion and activation of effector functions. The impact of TCR affinity for MHC/peptide complexes on the rate or extent of in vivo T cell expansion is not known. Here we show that in vivo expansion of complex T cell populations after bacterial infection is accompanied by an increase in their overall affinity for antigen. T cell populations that have undergone additional rounds of in vivo expansion express a narrower range of TCRs, have increased sensitivity for antigen in cytotoxic T lymphocyte assays, and bind MHC/peptide complexes with greater affinity. The selective expansion of higher affinity T cells provides an in vivo mechanism for optimizing the early detection of infected cells.
T淋巴细胞对受感染细胞的识别是由T细胞受体（TCR）与它们的配体相互作用介导的，这些配体是与病原体衍生肽复合的自身主要组织相容性复合体（MHC）分子。TCR与受感染细胞上可能数量较少的MHC/肽复合物的一系列相互作用传递信号，导致T淋巴细胞扩增和效应功能激活。TCR对MHC/肽复合物的亲和力对体内T细胞扩增速率或程度的影响尚不清楚。在这里，我们表明细菌感染后复杂T细胞群体的体内扩增伴随着它们对抗原的总体亲和力增加。经历了额外几轮体内扩增的T细胞群体表达的TCR范围更窄，在细胞毒性T淋巴细胞测定中对抗原的敏感性增加，并且以更高的亲和力结合MHC/肽复合物。高亲和力T细胞的选择性扩增为优化对受感染细胞的早期检测提供了一种体内机制。
