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 autoreactive 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: naïve, central memory, effector memory (EM) and effector memory re-expressing CD45RA (EMRA) cells. Objective: Our aim was to determine which memory subsets are involved in the CD8+ T cell deficiency and how these relate to clinical course. Methods: We used flow cytometry to analyze the memory phenotypes of T cells in the blood of 118 MS patients and 112 healthy subjects. Results: MS patients had a decreased frequency of EM (CD45RA–CD62L–) and EMRA (CD45RA+CD62L–) CD8+ T cells, which was present at the onset of disease and persisted throughout the clinical course. The frequencies of CD4+ EM and EMRA T cells were normal. Conclusion: Deficiency of effector memory CD8+ T cells is an early and persistent feature of MS and might underlie the impaired CD8+ T cell control of EBV.
Programmed death 1 is highly expressed on CD8+CD57+T cells in patients with stable multiple sclerosis and inhibits their cytotoxic response to Epstein-Barr virus
