<p>Interleukin-10 (IL-10) is a protein that inhibits the synthesis of a number of cytokines, including IFN-gamma, IL-2, IL-3, TNF and GM-CSF produced by activated macrophages and by helper T cells. Structurally, IL-10 is a protein of about 160 amino acids that contains four conserved cysteines involved in disulphide bonds [<cite idref="PUB00005262"/>]. IL-10 is highly similar to the <taxon tax_id="10376">Epstein-Barr virus</taxon> (strain GD1) (HHV-4) (Human herpesvirus 4) BCRF1 protein which inhibits the synthesis of gamma-interferon and to <taxon tax_id="12657">Equid herpesvirus 2</taxon> (Equine herpesvirus 2) protein E7.It is also similar, but to a lesser degree, with human protein mda-7 [<cite idref="PUB00004497"/>], a protein which has antiproliferative properties in human melanoma cells. Mda-7 only contains two of the four cysteines of IL-10.</p><p>This entry represents a conserved site at the second of three conserved cysteines. </p> Interleukin-10, conserved site