IL6R and Castleman disease: Tocilizumab, a humanized antihuman IL-6 receptor (IL-6R) antibody that binds to the IL-6-binding site of human IL-6R and competitively inhibits IL-6 signaling, is available as an approach to the therapeutically effective reagents against inflammatory diseases such as rheumatoid arthritis, juvenile idiopathic arthritis, Castleman's disease, and Crohn's disease [30, 31, 32, 33].