Deficiency of CD8+ effector memory T cells is an early and persistent feature of multiple sclerosis

Background: Patients with multiple sclerosis (MS) have a deficiency of circulating CD8(+) T cells, which might impair control of Epstein-Barr virus (EBV) and predispose to MS by allowing EBV-infected auto-reactive B cells to accumulate in the central nervous system. Based on the expression of CD45RA and CD62L, CD4(+) T cells and CD8(+) T cells can be subdivided into four subsets with distinct homing and functional properties, namely: naive, central memory, effector memory (EM) and effector memory reexpressing CD45RA (EMRA) cells