Mechanisms Of Age-related Changes in Transcriptional Regulation in lympphocytes

T细胞受体（TCR）为T细胞提供抗原识别的特异性。有能力的T细胞免疫系统依赖于不同的TCR库。然而，关于人类和小鼠TCR库的一般信息以及关于定义的病毒抗原的信息相对有限。我们使用高通量测序（HTS）和单细胞配对TCR分析以及小鼠CD 4 T细胞亚群（包括原始、记忆和调节性T细胞），对两种主要病毒表位（巨细胞病毒的pp 65（NLV）和甲型流感病毒的M1（GIL））特异性的人CD 8 + TCR库进行了全面分析。 我们对抗原特异性CD 8 + TCR库的分析鉴定了数千种新的NLV和GIL特异性α和β TCR序列以及数十种不同的CDR 3和CDR 3共有基序。这种多样性基本上大于先前描述的针对单个病毒表位的T细胞应答，对于私有和公共TCR克隆型，并且表现出高度的个体变异（每个受试者875，533个TCR-α或β）。然而，多样性受到优先V-J组合、CDR 3长度和CDR 3/CDR 3配对的有效限制。结合GILHLA-A2的两个GIL特异性TCR的结构为GIL特异性比NLV特异性库的多样性低提供了潜在的解释。这些抗病毒TCR占CD 8 + TCR库的3.4%，确保了对单个表位的广泛T细胞应答。我们对两种不同抗病毒T细胞反应的全面遗传、生物化学和结构描述可能有助于未来在个人水平上开发免疫或疾病的预测因子。 小鼠是研究最多的免疫系统模型，但α/β TCR库的信息有限。在这里，我们应用具有独特分子标识符的高通量测序来确定C57 BL/6小鼠中约14%的总CD 4 + T细胞的TCR-α和TCR-β序列。我们已经鉴定了1.67 X IO 5个独特的TCR-α和2.34 X IO 5个独特的TCR-β序列，预测的TCR-α和TCR-β库分别为2.79 X IO 6和5.09 X IO 6。TCR-β的库比TCR-α的库大1.6-1.8倍，并且原始TCR-α和TCR-β的库分别比记忆性CD 4 + T细胞的库大2.0和1.7倍。原始和记忆性CD 4 + T细胞具有大量重叠的TCR序列，反映了相对较小的库。CD 5 hi记忆性CD 4 + T细胞具有比CD 5lo记忆性CD 4 + T细胞更高的亲和力，但它们的α/β TCR库没有显著差异。调节性（Treg）CD 4 + T细胞的α/β TCR库介于初始和记忆T细胞之间，并且Treg的一部分（15%）由TCR-α（5.2 × 103）和TCR-β（9.7 × 103）的不同CDR 3氨基酸序列组成，可以代表来源于胸腺的天然Treg。总之，这些发现首次提供了小鼠CD 4 + T细胞α/β TCR库的深度信息，并为进一步阐明CD 4 + T细胞库的广泛性和特异性奠定了基础。

T cell receptor (TCR) provides the specificity of antigen-recognition for T cells. A competent T cell immune system depends on a diverse TCR repertoire. However, information on human and mouse TCR repertoires in general and to defined viral antigens is relatively limited. We performed a comprehensive analysis of TCR repertoires of human CD8+ TCR repertoires specific for two dominant viral epitopes: pp65 (NLV) of cytomegalovirus and M1 (GIL) of influenza A virus using the high-throughput sequencing (HTS) and single-cell paired TCR analysis and mouse CD4 T cell subsets including nave, memory, and regulatory T cells. Our analysis of antigen-specific CD8+ TCR repertoires resulted in identification of thousands of new NLV- and GIL-specific alpha and beta TCR sequences and dozens of distinct CDR3 and CDR3 consensus motifs. This diversity is substantially greater than previously described for T cell responses to single viral epitopes, both for private and public TCR clonotypes, and exhibited a high degree of individual variations (875,533 TCR-alpha or beta per subject). However, diversity is effectively restricted by preferential V-J combinations, CDR3 lengths, and CDR3/CDR3 pairings. Structures of two GIL-specific TCRs bound to GILHLA-A2 provided a potential explanation for the lower diversity of GIL-specific than NLV-specific repertoires. These anti-viral TCRs occupied up to 3.4% of the CD8+ TCR repertoire, ensuring broad T cell responses to single epitopes. Our comprehensive genetic, biochemical, and structural portrait of two different anti-viral T cell responses may contribute to the future development of predictors of immunity or disease at the personal level. Mouse is the most studied model of immune system and yet the information of alpha/beta TCR repertoire is limited. Here we applied high throughput sequencing with unique molecular identifier to determine TCR-alpha and TCR-beta sequences from approximately 14% of total CD4+ T cells in a C57BL/6 mouse. We have identified 1.67 x 105 unique TCR-alpha and 2.34 x 105 unique TCR-beta sequences with projected TCR-alpha and TCR-beta repertoires 2.79 x 106 and 5.09 x 106, respectively. The repertoire of TCR-beta was 1.6-1.8 time larger than that of TCR-alpha, and nave TCR-alpha and TCR-beta repertoires were 2.0 and 1.7 larger than those of memory CD4+ T cells, respectively. Nave and memory CD4+ T cells had substantial overlapping TCR sequences, reflecting relative small size of the repertoires. CD5hi memory CD4+ T cells have higher affinity than CD5lo memory CD4+ T cells but their Alpha/beta TCR repertoires were not significantly different. Alpha/beta TCR repertoires of regulatory (Treg) CD4+ T cells was between nave and memory T cells and a fraction of Treg (15%) consists of distinct CDR3 amino acid sequences of TCR-alpha (5.2 x 103) and TCR-beta (9.7 x 103), may represent the natural Treg derived from thymus. Together, these findings provide the depth information of alpha/betaTCR repertoire of mouse CD4+ T cells for the first time and serve as a foundation for further elucidating the broadness and specificity of CD4+ T cell repertoire.