In MS brain tissues, T-bet coexpression was recovered in CD20dim and CD69+ CD8+ T cells, and was accompanied by increased coproduction of granzyme K and B. These results indicate that coexpression of RUNX3 and EOMES, but not T-bet, defines CD8+ memory T cells with a pre-existing brain residency-associated phenotype such that they are prone to enter the CNS in MS. Here, RUNX3 is linked to myeloid sarcoma.