In conclusion, the quantitative deficiency in CD8+ T cell immunity to EBV reported in the present study might predispose to the development of MS by allowing the accumulation of EBV infected autoreactive B cells in the CNS.6 Boosting CD8+ T cell immunity to EBV by vaccination or by transferring EBV specific cytotoxic CD8+ T cells may be beneficial in preventing and treating MS. This evidence concerns the gene CD8A and myeloid sarcoma.