Th17 cells are a subset of CD4+ T cells that can secrete IL-17, IL-22, IL-6, and TNF-α, and have been implicated in autoimmune diseases, including multiple sclerosis, lupus, inflammatory bowel disease, RA, IDDM, and experimental autoimmune encephalomyelitis [98]–[101]. This evidence concerns the gene IL17A and rheumatoid arthritis.