Kaur Rimanpreet, Mehanna Nezar, Pradhan Atul, Xie Danielle, Li Kelin, Aubѐ Jeffrey, Rosati Barbara, Carlson David, Vorkas Charles K
bioRxiv. 2025 Feb 8:2025.02.06.636785. doi: 10.1101/2025.02.06.636785.
Mucosal-associated invariant T cells are highly conserved innate-like T cells in mammals recognized for their high baseline frequency in human blood and cytotoxic effector functions during infectious diseases, autoimmunity, and cancer. While the majority of these cells express a conserved CD8αβ+ TRAV1-2 T cell receptor recognizing microbially-derived Vitamin B2 intermediates presented by the evolutionarily conserved major histocompatibility complex I-related molecule, MR1, there is an emerging appreciation for diverse subsets that may be selected for in humans with distinct functions, including subpopulations that co-express CD4. Prior work has not examined T cell receptor (TCR) heterogeneity in CD4 MAIT cells, largely due to bias of identifying human MAIT cells as CD8 TRAV1-2 cells. In this study, we adopted an unbiased single-cell TCR-sequencing approach of total MR1-5-OP-RU-tetramer-reactive T cells and discovered that CD4 MAIT cells express highly diverse TRAV1-2 negative TCRs. To specifically characterize this TCR repertoire, we analyzed VDJ sequences of single MR1-5-OP-RU tetramer MAIT cells across two datasets and identified distinct TCR usage among CD4 MAIT cells including TRAV21, TRAV8 (TRAV8-1, TRAV8-2, TRAV8-3), and TRAV12 families (TRAV12-2, TRAV12-3), as well as more variable J chain and CDR3 sequences. Non-TRAV1-2 MAIT cell TCRs were also enriched after in vitro expansion, including with . These results indicate that mature human CD4 MAIT cells adopt distinct TCR usage from the canonical TRAV1-2 CD8 subset and suggest that alternative MR1 ligands in addition to riboflavin intermediates may select them.
黏膜相关恒定T细胞是哺乳动物中高度保守的固有样T细胞，因其在人类血液中的高基线频率以及在传染病、自身免疫和癌症中的细胞毒性效应功能而受到认可。虽然这些细胞中的大多数表达一种保守的CD8αβ+ TRAV1-2 T细胞受体，可识别由进化上保守的主要组织相容性复合体I相关分子MR1呈递的微生物衍生维生素B2中间体，但人们越来越认识到，在具有不同功能的人类中可能会选择出不同的亚群，包括共表达CD4的亚群。先前的研究尚未检查CD4⁺ MAIT细胞中的T细胞受体（TCR）异质性，这主要是由于将人类MAIT细胞鉴定为CD8⁺ TRAV1-2⁺细胞存在偏差。在本研究中，我们采用了一种无偏差的单细胞TCR测序方法，对总的MR1-5-OP-RU四聚体反应性T细胞进行测序，发现CD4⁺ MAIT细胞表达高度多样化的TRAV1-2阴性TCR。为了具体表征这个TCR库，我们分析了两个数据集中单个MR1-5-OP-RU四聚体⁺ MAIT细胞的VDJ序列，并确定了CD4⁺ MAIT细胞中不同的TCR使用情况，包括TRAV21、TRAV8（TRAV8-1、TRAV8-2、TRAV8-3）和TRAV12家族（TRAV12-2、TRAV12-3），以及更具变异性的J链和CDR3序列。非TRAV1-2 MAIT细胞TCR在体外扩增后也有所富集，包括使用……。这些结果表明，成熟的人类CD4⁺ MAIT细胞采用与经典的TRAV1-2⁺ CD8⁺亚群不同的TCR使用方式，并表明除了核黄素中间体外，其他MR1配体可能会选择它们。
