Interleukin 10 (IL-10) is a cytokine produced primarily by monocytes and to a lesser extent by lymphocytes.
IL-10 has pleiotropic effects in immunoregulation and inflammation such as inhibiting synthesis of IFN-gamma, IL-2, IL-3, TNF and GM-CSF produced by activated macrophages and helper T-cells. Defects in IL-10 are a cause of susceptibility to Crohn disease, an inflammatory bowel disease.