AUTHOR=Vacchini Alessandro , Chancellor Andrew , Spagnuolo Julian , Mori Lucia , De Libero Gennaro 

TITLE=MR1-Restricted T Cells Are Unprecedented Cancer Fighters

JOURNAL=Frontiers in Immunology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2020.00751

DOI=10.3389/fimmu.2020.00751

ISSN=1664-3224

ABSTRACT=<p>Non-polymorphic MHC class I-related molecule MR1 presents antigenic bacterial metabolites to mucosal-associated invariant T (MAIT) cells and self-antigens to MR1-restricted T (MR1T) cells. Both MR1-restricted T cell populations are readily identified in healthy individuals, with MAIT cells accounting for 1–10% of circulating T cells, while MR1T cells have frequencies comparable to peptide-specific T cells (&lt;0.1%). Self-reactive MR1T cells display a heterogeneous phenotype, and are capable of releasing both T<sub>H1</sub> and T<sub>H2</sub> cytokines, supporting not only activation of inflammation but also contributing to its regulation. Importantly, MR1T cells recognize and kill a diverse range of MR1-expressing tumor cells. On the other hand, evidence suggests MAIT cells augment cancer growth and metastases. This review addresses the potential role of MR1-restricted T cells in controlling tumor cells, facilitating their elimination and regulating cancer immunity. We also discuss therapeutic opportunities surrounding MR1-restricted T cells in cancer.</p>