Interleukin 10 (IL-10) is a α-helical homodimeric cytokine with immunosuppressive and anti-inflammatory properties. It inhibits the secretion of Tʜ1 cytokines such as IL-1, IFN-γ, and TNFα, and the surface expression of molecules for antigen presentation. On the other hand, IL-10 promotes the humoral response, through stimulation of the Tʜ2 response, B cell maturation, and antibody secretion. After secretion, IL-10 binds the receptor IL-10 Rα/IL-10 R1 on target cells. IL-10 is mainly secreted by monocytes, Tʜ2 lymphocytes, regulatory T cells, some B cell subsets, dendritic cells, macrophages, natural killer cells, eosinophils, neutrophils, and mastocytes, but also keratinocytes and hepatic stellate cells.
IL-10 plays a central role in the control mechanisms that limit inflammatory responses and ultimately prevent immunopathology. Mutations of IL-10 gene can be also associated to susceptibility to infections, autoimmune diseases, and allergy.
Human IL-10 protein shares 73% homology with mouse IL-10 protein, and it can activate mouse cells, however mouse IL-10 fails to activate human cells.