Misinitiation of intrathymic MART-1 transcription and biased TCR usage explain the high frequency of MART-1-specific T cells

Item Type:	Article
Title:	Misinitiation of intrathymic MART-1 transcription and biased TCR usage explain the high frequency of MART-1-specific T cells
Creators Name:	Pinto, S. and Sommermeyer, D. and Michel, C. and Wilde, S. and Schendel, D. and Uckert, W. and Blankenstein, T. and Kyewski, B.
Abstract:	Immunity to tumor differentiation antigens, such as melanoma antigen recognized by T cells 1 (MART-1), has been comprehensively studied. Intriguingly, CD8(+) T cells specific for the MART-126(27)-35 epitope in the context of HLA-A0201 are about 100 times more abundant compared with T cells specific for other tumor-associated antigens. Moreover, MART-1-specific CD8(+) T cells show a highly biased usage of the Vα-region gene TRAV12-2. Here, we provide independent support for this notion, by showing that the combinatorial pairing of different TCR{alpha}- and TCR{beta}- chains derived from HLA-A2-MART-126 -35 -specific CD8(+) T-cell clones is unusually permissive in conferring MART-1 specificity, provided the CDR1{alpha} TRAV12-2 region is used. Whether TCR bias alone accounts for the unusual abundance of HLA-A2-MART-126 -35 -specific CD8(+) T cells has remained conjectural. Here, we provide an alternative explanation: mis-initiated transcription of the MART-1 gene resulting in truncated mRNA isoforms leads to lack of promiscuous transcription of the MART-126 -35 epitope in human medullary thymic epithelial cells and, consequently, evasion of central self-tolerance towards this epitope. Thus, biased TCR usage and leaky central tolerance might act in an independent and additive manner to confer high frequency of MART-126 -35 -specific CD8(+) T cells.
Keywords:	Central Tolerance, Human Medullary Thymic Epithelial Cells, MART-1, Melanoma, Promiscuous Gene Expression
Source:	European Journal of Immunology
ISSN:	0014-2980
Publisher:	Wiley-Blackwell
Volume:	44
Number:	9
Page Range:	2811-2821
Date:	September 2014
Official Publication:	https://doi.org/10.1002/eji.201444499
PubMed:	View item in PubMed

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