Originally identified as a gene induced by IL-9 in mouse T cells and mast cells, IL-22 is a member of the IL-10 family of cytokines. IL-22 inhibits IL-4 production by Th2 cells, and induces acute phase reactants in the pancreas and liver. The IL-22 receptor complex consists of two receptor subunits, IL-22R and IL-10R-beta that belong to the class II cytokine receptor family. Recombinant human IL-22 is a non-disulfide-linked homodimeric protein.