The therapy of autoimmune diseases by anti-interleukin-6 receptor antibody

Interleukin (IL)-6 plays essential roles not only in the immune response, but also in haematopoiesis and the central nervous system. Deregulated production of IL-6 has been found in chronic inflammatory autoimmune diseases, such as rheumatoid arthritis (RA), systemic onset juvenile idiopathic arthritis (soJIA), Crohn's disease (CD) and systemic lupus erythematosus (SLE). Furthermore, IL-6 activities can explain many symptoms of these diseases. More importantly, serum levels of IL-6 are correlated with disease activity. Based on these facts, the authors planned to develop a humanized anti-IL-6 receptor antibody, tocilizumab (previously known as MRA), as a therapeutic agent for these inflammatory autoimmune diseases. Tocilizumab is a neutralising antibody to suppress IL-6 signalling mediated by both membranous and soluble IL-6R. Clinical efficacy of tocilizumab in RA, soJIA, adult-onset Still's disease or CD patients has been discussed in this review. In all of these diseases, tocilizumab has improved the disease activity, suggesting that IL-6 plays an essential role in the pathogenesis of these diseases.