Check MAIT

Abstract

The evolutionary conservation of T lymphocyte subsets bearing αβ TCRs using invariant α-chains is indicative of unique and important functions. Among these T lymphocytes, NKT cells that express an invariant TCRα-chain and recognize lipid Ags presented by the nonclassical MHC class I molecule CD1d are probably the most studied. However, a new population of evolutionarily conserved T cells with another invariant TCRα rearrangement was recently characterized. These cells, which are very abundant in humans, tend to reside in mucosal tissues and, therefore, were named mucosal-associated invariant T (MAIT) cells. Until recently, little was known about MAIT cells; however, several recent advances in our understanding of MAIT cell characteristics and functions secure their upcoming rise to fame in the immunology field and in clinical practice.

Figure 1

Recognition by the MAIT T cell antigen receptor of vitamin metabolites presented by MR1 molecules. (A) Chemical structures of 3 vitamin metabolites, 6-formyl pterin (6-FP), 7-hydroxy-6-methyl-8-D-ribityllumazine (RL-6-Me-7-OH) and reduced 6-hydroxymethyl-8-D-ribityllumazine (RL-6-CH2OH) that have been shown to be presented by MR1 molecules. (B) Antigenic potency of these metabolites for MAIT cells. (C) The interaction between the MAIT TCR and MR1 molecules presenting the vitamin metabolites. They key role of CDR3α-encoded Tyr95 in interacting with the ribityl moiety found on stimulatory antigen is depicted.