IL15 and rheumatoid arthritis: Nevertheless, dysregulation of IL-15 expression with concomitant elevated levels of IL-15 has been reported in several autoimmune diseases (17, 18), including rheumatoid arthritis (19), psoriasis (20), lupus (21), sarcoidosis (22, 23), type 1 diabetes (24), celiac disease (25), and inflammatory bowel diseases (26).