Interleukin-10 (IL-10) is encoded by the IL10 gene and expressed in monocytes and Type 2 T helper cells (Th2). The biological activities of IL-10 are mediated by the IL-10 receptor complex, which is composed of the ligand-binding IL-10 Rα/R1 and the accessory IL-10 Rβ/R2 subunits. IL-10 is capable of inhibiting the synthesis of a number of cytokines, including IFN-gamma, IL-2, IL-3, TNF and GM-CSF produced by activated macrophages and by T helper cells. IL-10 is classified as a class 2 cytokine which consist of IL-10, IL-19, IL-20, IL-22, IL-24 and IL-26, several interferons and interferon-like molecules. Mature murine IL-10 shares 70 %-77 % amino acid sequence identity with human, bovine, porcine IL-10, but murine IL-10 does not act on human cells.