For example, histopathologic examinations of postmortem brain tissue reveal that CD8 T cells outnumber CD4 T cells in MS lesions.16,17 Moreover, CD8 T-cell lines reactive to myelin have been demonstrated to induce EAE.18,19 Nevertheless, the effect of the CD226 risk allele on CD8 T-cell functions remains to be elucidated. Here, CD226 is linked to myeloid sarcoma.