IFNβ therapy progressively normalizes the increased ex vivo T lymphocyte apoptosis observed in active patients with multiple sclerosis

Abnormal apoptosis has been reported in circulating T lymphocytes in patients with multiple sclerosis. The effects of 12 months of IFNβ treatment in T and B lymphocyte spontaneous ex vivo apoptosis were studied in patients with MS. Peripheral blood mononuclear cells were obtained from 48 patients before and at 1, 6 and 12 months after treatment with IFNβ. Spontaneous ex vivo apoptosis was quantified by four-color flow cytometry. A significant reduction and normalization of the percentage of apoptotic cells was found in all T lymphocyte subsets. B cell apoptosis values were unaffected by therapy; Relapses of the clinical activity of the disease were associated to transitory upturns of lymphocyte apoptosis. In conclusion, IFNβ therapy progressively normalizes the increased ex vivo T lymphocyte apoptosis observed in MS. However, it is not clear if this reduction in spontaneous T lymphocyte apoptosis is due to direct effect of IFNβ or secondary to decreased clinical and sub-clinical activity.