IFNβ-1a therapy for multiple sclerosis expands regulatory CD8+ T cells and decreases memory CD8+ subset: A longitudinal 1-year study

The beneficial effects of interferon β-1a (IFNβ-1a) in multiple sclerosis (MS) remain only partially understood. CD8+ T cells are key cells in MS pathogenesis that contribute to axonal damage in MS, whereas CD4+ regulatory T cells (TReg) and CD8+ regulatory/suppressor T cells (Ts) play an important role in protecting against subsequent MS activity. We analysed ex vivo changes on TReg and on the different subsets of CD4+ and CD8+ T lymphocytes, before IFNβ-1a (Rebif) therapy and at 3, 6, and 12 months after treatment, in 23 MS patients and in 26 healthy controls. IFNβ-1a significantly increased the proportions of CD4+ TReg and regulatory CD8+ T cells (Tr). Memory CD8+ T cells were significantly decreased after 1 year of treatment, maybe reflecting down-regulation of abnormally persistent systemic activation in MS patients. After 1 year of IFNβ-1a, a direct correlation was observed between plasmacytoid dendritic cells and effector CD8+ T cells.