MR1 presentation of vitamin B-based metabolite ligands

Abstract

The major histocompatibility complex class I-related molecule MR1 can bind a novel class of antigens, namely a family of related small organic vitamin B metabolites. When bound to MR1 these metabolites are presented to a population of innate-like T cells, mucosal-associated invariant T (MAIT) cells that express a semi-invariant T cell receptor (TCR). Several non-activating and activating MR1-restricted ligands have been described, which are the degradation products of, or intermediates of, vitamin B9 (folic acid) or vitamin B2 (riboflavin), respectively. The MAIT-activating intermediates of the riboflavin synthesis pathway are unique to a wide range of microbes, and accordingly represent a m..