Increase of CD8+ T-effector memory cells in peripheral blood of patients with relapsing–remitting multiple sclerosis compared to healthy controls

CCR7 and CD45RA expression on CD4+ and CD8+ T-cells in blood (PB) of 16 patients with multiple sclerosis (MS) and 16 healthy controls and cerebrospinal fluid (CSF) of 10 patients suffering from MS were analysed by flow cytometric measurements. T-cells were divided by their distinct homing potentials and effector-functions in three groups: naïve T-cells (CCR7+, CD45RA+), central memory T-cells (TCM) (CCR7+, CD45RA−) and effector memory T-cells (TEM) (CCR7−, CD45RA−). There was a significant increase of CD8+ TEM-cells in PB of MS patients compared to healthy controls, indicating systemic immune activation. Further we found a relative depletion of CD8+ TEM-cells in CSF of MS patients compared to matching blood samples, suggesting that these cells represent the effector arm of the immune response and infiltrate the brain tissue at the sites of inflammation.