In healthy individuals, EBV infection is kept under rigorous control by EBV-specificimmune responses, especially by cytotoxic CD8+ T cells, which killproliferating and lytically infected B cells by targeting the various EBV-encoded latentand lytic proteins respectively.7, 8 We have hypothesized that defective elimination ofEBV-infected B cells by cytotoxic CD8+ T cells might predispose to thedevelopment of MS by enabling the accumulation of EBV-infected autoreactive B cells inthe central nervous system (CNS).9, 10. The gene discussed is CD8A; the disease is myeloid sarcoma.