Interleukin 10 (IL-10, CSIF) is an anti-inflammatory cytokine mainly produced by macrophages and Th2 cells. IL-10 is an 18.6 kDa protein of 160 amino acid residues that shares over 80% sequence homology with the Epstein-Barr Virus protein (BCRFI).
The reported biological activities of IL-10, which maybe interrelated, include inhibition of macrophage-mediated cytokine synthesis, suppression of the delayed-type hyper-sensitivity response, and stimulation of the Th2 cell response which results in elevated antibody production. IL-10 functions by inhibiting pro-inflammatory cytokines made by macrophages and regulatory T cells including IFN-gamma, TNF-alpha, IL-2, and IL-3, IL-4, and GM-CSF.
IL-10 is also known to suppress antigen presentation on antigen presenting cells, enhances B cell survival, proliferation, and antibody production. IL-10 can block NF-kappa B activity, and is involved in the regulation of the JAK-STAT signaling pathway. While human IL-10 can act on murine cells, murine IL-10 cannot act on human cells. Binds to a retinoid X receptor (RXR) responsive element from the cellular retinol-binding protein II promoter (CRBPII-RXRE).
IL-10 inhibits the 9-cis-retinoic acid-dependent RXR alpha transcription activation of the retinoic acid responsive element. Knockout studies in mice suggest the function of this cytokine as an essential immunoregulator in the intestinal tract.