CD8A and myeloid sarcoma: Usually, the proliferating infected B cells are eventually eliminated by EBV specific cytotoxic CD8+ T cells but latently infected non-proliferating memory B cells persist in the individual for life.5 We have hypothesised that a genetically determined defect in the elimination of EBV infected B cells by cytotoxic CD8+ T cells might predispose to the development of MS by allowing the accumulation of EBV infected autoreactive B cells in the CNS.6 Recently it has been demonstrated that a substantial proportion of the B cells and plasma cells in the MS brain are infected with EBV.7