Increased spontaneous ex vivo apoptosis and subset alterations in peripheral blood T cells from patients with multiple sclerosis.

In order to characterize the immunophenotype and the lymphocyte apoptosis in multiple sclerosis (MS) patients, the peripheral blood lymphocytes of 46 MS patients and 12 healthy volunteers were studied by flow cytometry. Immunophenotypic alterations included significant increases in T CD4+ lymphocytes and reductions in the percentages of CD3+ and CD8+ T cells. After 24 h of culture spontaneous apoptosis was increased in almost T lymphocyte subsets from MS patients and it was significantly higher in those patients who had suffered more than two relapses in the two previous years. The incidence of spontaneous apoptosis was not dependent on FasL-Fas interactions and correlated with the percentages of cells positive for active caspases but not with percentages of Fas+ cells. The increased susceptibility to apoptosis of peripheral blood T lymphocytes from MS patients is difficult to reconcile with the previously proposed role of a defective lymphocyte apoptosis in the pathophysiology of MS.