Interleukin 6 (IL-6) is a pleiotropic glycoprotein belonging to the IL-6 family of cytokines. IL-6 is a multifunctional cytokine with well-defined pro- and anti-inflammatory properties. IL-6 is secreted by T cells and macrophages to stimulate immune response, e.g. during infection and after trauma, especially burns or other tissue damage leading to inflammation. The O-linked sugar chain of IL-6 is thought to contribute to the stability of the cytokine through polymerization suppression and/or conformational changes, exemplifying the significance of its expression in a human expression system (which allows proper glycosylation).