IL6 and Castleman disease: Although IL-6 is critical for many cellular functions, including B cell antibody production, dysregulation of IL-6 production has been implicated in the pathogenesis of numerous autoimmune/inflammatory diseases and cancers, including RA, SLE, inflammatory bowel disease, Crohn's disease, Castleman's disease, multiple myeloma, Hodgkin's disease, colon cancer, and cancer cachexia [55]–[57].