Flow cytometry plots of species-mismatched MR1–5-OP-RU and MR1–6-FP tetramer staining. Human, cattle, pig-tailed macaque, mouse, and pig MR1–5-OP-RU and MR1–6-FP tetramers were used to stain human PBMC, cattle PBMC, lymphocytes from MAIT cell boosted mouse spleen, pig-tailed macaque PBMC, sheep PBMC or pig PBMC. Representative final gating is shown for each species and each, MR1–5-OP-RU and MR1–6-FP tetramer. 5-OP-RU, 5-(2-oxopropylideneamino)-6-d-ribitylaminouracil; 6-FP, 6-formylpterin; MAIT, mucosal-associated invariant T; MR1, MHC-I related protein 1; PBMC, peripheral blood mononuclear cell.