IL18 and rheumatoid arthritis: IL-18, formerly called interferon (IFN)-γ-inducing factor, is an important proinflammatory cytokine belong to the IL-1 family that is produced by a wide range of immune cells, such as monocytes, activated macrophages and Kupffer cells [4].The imbalance of Th1/Th2 type cytokines plays important roles in the induction and development of several autoimmune diseases, and IL-18 is an important mediator involved in the pathogenesis of Th1- and Th2-mediated diseases including RA and SLE [5,6].