CD8A and type 2 diabetes mellitus: Metabolites from the riboflavin biosynthesis pathway are necessary for MAIT cell intra-thymic development and subsequent peripheral expansion in mice.25,52 Indeed, colonization of riboflavin synthesizing bacteria such as Escherichia coli or Proteus mirabilis promotes MAIT cell development.25,52 In our study we observed an increase of CD8+ MAIT cells after two weeks of histidine supplementation in participants with T2D.