Consistent with these findings, studies on CD8+ CD57+ T cells in MS patients, which act as effector cytotoxic cells against EBV-infected cells, revealed that PD-1 expression impairs degranulation and cytotoxicity in these cells, compromising the immune control of EBV during the remission phase and contributing to disease exacerbation [23]. The gene discussed is CD8A; the disease is myeloid sarcoma.