Interleukin-22 is a new cytokine that regulates the production of acute phase proteins of the immunological response. It is produced by activated Th1 and NK cells acting primarily on epithelial cells and is involved in inflammatory responses. IL-22 plays a protective role in T cell-mediated hepatitis induced by Concanavalin A, acting as a survival factor for hepatocytes. IL-22 is present in high quantities in the blood of Crohn's disease patients in contrast to IFN-gamma and IL-17 levels.