To determine if Mtb-reactive MR1-restricted T-cell responses are correlated with exposure to Mtb, we performed flow-cytometric ex vivo analyses of MR1-restricted, Mtb-reactive MAIT cells from subjects from all three Mtb exposure groups (uninfected, n = 6; LTBI, n = 5, active TB, n = 8). This evidence concerns the gene MR1 and tuberculosis.