Apoptosis of T cells in peripheral blood and cerebrospinal fluid is associated with disease activity of multiple sclerosis.

Apoptotic elimination of pathogenic T cells is considered to be one of regulatory mechanisms in multiple sclerosis (MS). To explore the potential relationship between Fas-mediated apoptosis and the disease course of MS, we examined apoptosis, defined by annexin V (AV) binding, and Fas (CD95) expression in CD4+ and in CD8+ T cells in MS patients by using five-color flow cytometry. The percentage of AV+CD4+CD3+ cells and CD95+AV+CD4+CD3+ cells in peripheral blood and cerebrospinal fluid (CSF) were significantly decreased in active MS patients compared with inactive MS patients. A significantly lower proportion of CD95+AV+CD8+CD3+ cells in CSF was observed in active MS patients compared with inactive MS patients, but not in peripheral blood. These results indicate that the resistance of T cells to Fas-mediated apoptosis is involved in exacerbation of MS and/or that Fas-mediated apoptosis of T cells is associated with remission of MS.