Transgenic IL6-KO mouse models are characterized by a unique resistance to several inflammatory conditions such as experimental autoimmune arthritis or encephalomyelitis [69, 70]; accordingly, IL-6 plays a central role in the pathogenesis of several autoimmune diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, adult onset Still's disease, systemic lupus erythematosus, Takayasu's arteritis, and inflammatory bowel disease [69, 72, 75]. Here, IL6 is linked to adult-onset Still disease.