Major histocompatibility complex (MHC) class-1-related protein (MR1), is a non-classical MHC class I molecule that has been shown to bind a variety of exogenous ligands including a range of chemical scaffolds related to vitamin B metabolites and pharmaceutical drugs. As a target for MAIT and other MR1 restricted T cell receptors there is a strong interest in the therapeutic potential of targeting this axis in infectious diseases and cancer. Here we describe efforts to understand the breadth of MR1 ligands using an unbiased ligand discovery approach based on liquid chromatography - mass spectrometry and advanced AI-based chemoinformatics using both refolded MR1 molecules and engineered MR1 expressing cell lines as sources of endogenous and selected exogenous ligands.