CD8A and myeloid sarcoma: However, it has also been reported that EBV-specific CD8 T cells from MS patients display a dysfunctional phenotype, like reduced IFNγ production and cytotoxic activity (55, 58, 185), and that the frequency and functionality of EBV-specific CD4 and CD8 T cells progressively decreases with increasing disease duration (54, 55, 58).