Mucosal associated invariant T (MAIT) cells represent a unique population of invariant T cells that form a major subset of the innate-like T cell compartment in humans. In contrast to conventional T cells and Natural Killer T (NKT) cells, which recognise peptides and lipids in the context of MHC and CD1d respectively, MAIT cells are restricted to the non-classical MHC Class-1 like element, MR1. Recently, it has been shown that MAIT cells recognize and are activated by microbial metabolites presented on MR1 (1,3), via their semi-invariant T cell receptor, thus suggesting that MAIT cells play a critical and non-redundant role in pathogen recognition. Despite their apparent importance, our understanding of MAIT cell biology has been severely hampered by the lack of a clear manner in which to identify MAIT cells in mice. In the present study, we show that by using MR1 tetramers loaded with agonist antigens (2), we can specifically and unequivocally identify MAIT cells in both central and peripheral lymphoid organs of wild-type mice by flow cytometry, and furthermore, we provide exciting initial insight into their basal phenotypic profile and functional potential. This work paves the way for exploring MAIT cells in the context of different immune responses and deciphering their role in the immune system.
(Short title - Meet: Mouse Maits.)