MHC-related protein 1–restricted recognition of cancer via a semi-invariant TCR-α chain
Garry Dolton, … , Barbara Szomolay, Andrew K. Sewell
Garry Dolton, … , Barbara Szomolay, Andrew K. Sewell
Published January 2, 2025
Citation Information: J Clin Invest. 2025;135(1):e181895. https://doi.org/10.1172/JCI181895.
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MHC-related protein 1–restricted recognition of cancer via a semi-invariant TCR-α chain

Abstract

The T cell antigen presentation platform MR1 consists of 6 allomorphs in humans that differ by no more than 5 amino acids. The principal function of this highly conserved molecule involves presenting microbial metabolites to the abundant mucosal-associated invariant T (MAIT) cell subset. Recent developments suggest that the role of MR1 extends to presenting antigens from cancer cells, a function dependent on the K43 residue in the MR1 antigen binding cleft. Here, we successfully cultured cancer-activated, MR1-restricted T cells from multiple donors and confirmed that they recognized a wide range of cancer types expressing the most common MR1*01 and/or MR1*02 allomorphs (over 95% of the population), while remaining inert to healthy cells including healthy B cells and monocytes. Curiously, in all but one donor these T cells were found to incorporate a conserved TCR-α chain motif, CAXYGGSQGNLIF (where X represents 3–5 amino acids), because of pairing between 10 different TRAV genes and the TRAJ42 gene segment. This semi-invariance in the TCR-α chain is reminiscent of MAIT cells and suggests recognition of a conserved antigen bound to K43.

Authors

Garry Dolton, Hannah Thomas, Li Rong Tan, Cristina Rius Rafael, Stephanie Doetsch, Giulia-Andreea Ionescu, Lucia F. Cardo, Michael D. Crowther, Enas Behiry, Théo Morin, Marine E. Caillaud, Devinder Srai, Lucia Parolini, Md Samiul Hasan, Anna Fuller, Katie Topley, Aaron Wall, Jade R. Hopkins, Nader Omidvar, Caroline Alvares, Joanna Zabkiewicz, John Frater, Barbara Szomolay, Andrew K. Sewell

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Figure 2

Characterization of the MC.27.759S T cell receptor.

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Characterization of the MC.27.759S T cell receptor. (A) MC.27.759S and M...
(A) MC.27.759S and MC.7.G5 T cell clone killing assay of various cancer cells (MR1 allotype indicated). A549 (lung) MR1 KO (–/–) by CRISPR/Cas9, with a transgene for scβ2M-MR1*01. Flow cytometry–based killing assay at a 1:2 T cell–to–cancer cell ratio for 24 hours. Quadruplicate conditions with error bars depicting SD. (B) TCR-α and -β chains of MC.27.759S and MC.7.G5. Germline amino acid residues of variable (V) and joining (J) regions are underlined and inserted amino acids not underlined. (C) CD8 phenotyping of MC.27.759S and MC.7.G5 T cell clones with CD8-α and CD8-β–specific antibodies. MAIT and CD8+ T cell line used as a controls for CD8-αα or CD8-αβ expression. (D) CD161 phenotyping of MC.27.759S and MC.7.G5 T cell clones, using MAIT and CD3/CD28-amplified T cells as in C. The MFI of CD161 staining is shown. (E) CD69 assays for 24 hours of MC.27.759S and MC.7.G5 TCR-transduced Jurkat cells expressing no CD8, CD8-αα or CD8-αβ, versus cancer cells. Untransduced values have been subtracted. Triplicate conditions with errors bars depicting SD. (F) CD69 assays for 24 hours of A-F7 (MAIT) TCR-transduced Jurkat cells expressing no CD8, CD8-αα or CD8-αβ versus M. smeg–infected A549 cells or 100 μg of 5-A-RU. Untransduced values have been subtracted. Triplicate conditions with errors bars depicting SD. (G) CD69 assays (24 hours) of MC.27.759S TCR-transduced Jurkat cells against MR1*01/*01 or *01/*02 cancer cells and healthy cells. Duplicate for monocytes from donors 1 and 2 due to the low number of cells available, or triplicate conditions with errors bars showing SD. (H) CD69 assay (24 hours) with MC.27.759S or JMA (positive control for MR1 on healthy cells) TCR-transduced Jurkat cells versus melanoma and inactivated or activated B cells. Triplicate conditions with errors bars showing SD. Cancer cells include melanoma (FM74, FM72, MEL624, MEL526, and FM86), Ewing sarcoma (RD-ES and ES-5838), Leukemia/CML (K-562), cervical (SiHa), breast (MDA-MB-231), kidney (ACHN) and pancreatic (MIA PaCa-2) cancers.