[B-cell Depletion Therapy in Multiple Sclerosis]

Since the initial observation of increased immunoglobulin concentrations in the cerebrospinal fluid of patients with multiple sclerosis (MS) in the 1940s, B cells have been considered to participate in the pathology of MS through the production of autoantibodies reactive against central nervous system antigens. However, it is now recognized that B cells contribute to MS relapses by antibody-independent activities, including presenting antigens to T cells and releasing pro-inflammatory cytokines. In addition, the recent identification of B cell-rich follicle-like structures in the meninges of patients with MS suggests that pathogenic roles of B cells also exist at the progressive phase. Recently, large-scale clinical trials have demonstrated the efficacy of B-cell depletion therapy using ocrelizumab, an anti-CD20-antibody, in relapsing-remitting as well as primary progressive MS; these findings have led to the approval of ocrelizumab by the Food and Drug Administration and the European Medical Agency for treating these conditions. B-cell depletion therapy is an important treatment option for MS based on its favorable benefit to risk balance in relapsing remitting MS, and as it is the only drug that has currently been demonstrated to be effective in treating primary progressive MS.