Expressed primarily in monocytes and less in lymphocytes by human IL10 Gene, Interleukin-10 is a cytokine with pleiotropic effects in immunoregulation and inflammation. It down-regulates expression of Th1 cytokines, MHC class II antigens, and costimulatory molecules on macrophages. It also enhances B cell survival, proliferation, and antibody production. This cytokine can block NF-kappa B activity, and is involved in the regulation of the JAK-STAT signaling pathway. Studies in mice suggest that this cytokine as an essential immunoregulator in the intestinal tract. (From LocusLink)