Interleukin 10（IL10）, also known as cytokine
synthesis inhibitory factor （CSIF）,is a secreted protein and belongs to the
IL-10 family. IL-10 is secreted by many activated hematopoietic cell types as
well as hepatic stellate cells, keratinocytes, and placental cytotrophoblasts .
IL-10 is an anti-inflammatory TH2 cytokine that has a critical role in limiting
the immune response to pathogens to prevent host damage. As IL-10 in produced
in several T helper populations, it is proposed that it provides a feedback
loop to limit the effector functions of macrophages and DCs on T cells. Once
expressed, IL-10 signals through the IL-10 receptor （IL-10R） to activate STAT3.
As IL-10 is a strong inhibitor of inflammation, it has become a viable
biomarker for various diseases and conditions as well as a therapeutic molecule
for certain conditions. In addition to elevated levels in parasitic infection,
high expression levels of IL-10 are also found in retroviral infections
inducing immunodeficiency. The immunosuppressive properties of IL-10 suggest a
possible clinical use of IL-10 in suppressing rejections of grafts after organ
transplantations.