Increased CD8+ central memory T cells in patients with multiple sclerosis.

A T-cell-mediated autoimmune process against central nervous system myelin is believed to underlie the pathogenesis of multiple sclerosis (MS). Formation of immunological memory is based on the differentiation of naïve T cells to memory T cells after exposure to antigens and specific cytokines. The aim of this study was to analyse peripheral blood mononuclear cells in patients with MS for different T-cell subsets including naïve and memory T cells. Flow cytometry and enzyme-linked immunosorbent assay were used to analyse memory T-cell subsets and plasma concentration of interleukin-15 (IL-15) in peripheral blood of MS patients, patients with other neurological disorders and healthy controls. MS patients had a skewed distribution of T cells with an increased level of CD8+/CCR7+/CD45RA - central memory T cells (TCM) compared to healthy controls. In addition, MS patients showed significantly higher levels of plasma IL-15 than healthy controls did. Upregulated CD8+ TCM in MS patients may reflect a persistent chronic inflammatory response that may have been induced during early stages of the disease. This derangement may be important for maintaining chronic inflammation in MS.