Cytokines are small, soluble proteins with pleiotropic effects on a variety of cell types. Cytokines have a regulatory function over the immune system and mediate aspects of inflammatory response. They exert their biological effects through the binding of membrane-bound receptors which, in turn, initiate signal transduction cascades and elicit physiological changes in their target cell. IL-17RB is a member of the cytokine receptor family and acts as a receptor for the proinflammatory cytokines IL-17B and IL-17E. It may play a role in hematopoietic cell differentiation and growth. IL-17RB expression is high in liver, colon, brain, kidney and testis. IL-17RB is detected in fibroblast-like synoviocytes of rheumatoid arthritis patients.