Interleukin-10 (IL-10) is also known as human cytokine synthesis inhibitory factor (CSIF) and inhibits the synthesis of pro-inflammatory cytokines like IFN-gamma, IL2, IL3, TNF and GM-CSF produced by activated macrophages and by helper T-cells. This protein has effects in immunoregulation and inflammation and downregulates the expression of Th1 cytokines, MHC class II antigens, and costimulatory molecules on macrophages.