To determine the frequency of in vivo activated T(H)1 lymphocytes, T-cell subsets of 9 multiple sclerosis patients with active disease and 17 healthy controls were analyzed by immunostaining for CCR5, CD26, and their expression of interleukin-2, interferon-gamma, and tumor necrosis factor-alpha. The numbers of CCR5+ interferon-gamma- and tumor necrosis factor-alpha-producing T cells were significantly increased in the peripheral blood of multiple sclerosis patients. CCR5 expression may be a useful marker to identify effector cells in multiple sclerosis and could be used as a tool for monitoring disease activity.
