Characterisation of MR1-reactive T cells using MR1-Ag tetramers

• Main Author: Lee, Clarice Zi Qi
• Other Authors: -
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Science::Biological sciences
• Online Access: https://hdl.handle.net/10356/166589
• Institution: Nanyang Technological University

The major histocompatibility complex class I-related protein 1 (MR1) presents small non-peptide antigens to unconventional T cells, most notably mucosal-associated invariant T (MAIT) cells, and MR1-reactive T (MR1T) cells. MAIT cells are highly specific for microbial riboflavin derivatives. MR1T cells are rare, phenotypically and functionally diverse, and some display tumour-directed cytotoxicity, hinting at novel antigen(s). However, MR1T cells and their antigens are not fully characterised. Recent literature showed that adducts of nucleobases and small molecule metabolites are potential MR1T cell antigens. In this study, we determined the functionality of these antigens using reporter cell lines and probed primary MR1T cell functions. Our results show an adduct of the nucleobase adenine and small molecule malondialdehyde, M3ADE, is an MR1T cell antigen and likely binds MR1 via Schiff base formation with lysine-43. M3ADE potently upregulated MR1 expression on transformed B cells which activated some MR1T cells while inhibiting the endogenous response of others. Primary MR1T cells isolated from healthy donors using recombinant human MR1-M3ADE tetramers released Th1 cytokines and were cytotoxic towards M3ADE-pulsed, MR1-expressing transformed cell lines, resembling cytotoxic T lymphocyte functions. This study gives important insights to MR1T cell antigen specificity and functions that could be harnessed for therapeutics.