CD4 and myeloid sarcoma: Clinical data have confirmed the importance of these processes in individuals with MS, showing that many of the gene loci conferring increased risk of the disease are predicted to affect CD4+ T cell activation and differentiation9; that there is an MS-associated immune gene signature in a subset of CD4+ T cells in monozygotic twins discordant for the disease10; that CD4+ T cells start colonizing the CNS from early stages of the disease11; and that therapies targeting T cell migration can be effective in ameliorating MS12.