Interleukin 6 (IL-6) is a multifunctional cytokine that plays important roles in host defense, acute phase reactions, immune responses, nerve cell functions and hematopoiesis (1-5).
IL-6 is a prototypic member of the IL-6 superfamily of cytokines that share gp130 as a component required for signal transduction (4). The rat, mouse and human IL-6 cDNAs have been cloned (6-9). Rat IL-6 cDNA encodes a 211 amino acid (aa) residue precursor polypeptide with a hydrophobic signal peptide that is cleaved to generate the 187 aa residue mature protein. At the protein sequence level, there is approximately 39% identity between rat and human, and 87% identity between mouse and rat IL-6 (6).
IL-6 is expressed by a variety of normal and transformed lymphoid and non-lymphoid cells. The production of IL-6 is up-regulated by numerous signals such as mitogenic or antigenic stimulation, lipopolysaccharides, calcium ionophores, cytokines and viruses. IL-4, IL-10 and IL-13 inhibit IL-6 expression in monocytes. Elevated serum IL-6 levels have been observed in a number of pathological conditions, including bacterial and viral infections,trauma, autoimmune diseases, inflammations and malignancies (1-5).
Hirano, T. (1998) "Interleukin 6" in The Cytokine Handbook, 3rd. ed. Academic Press,New York, p. 197.
Hibi, M. et al. (1996) J. Mol. Med. 74:1.
Hirano, T. et al. (1994) Stem Cells 12:262.
Taga, T. and T. Kishimoto (1997) Annu. Rev. Immunol. 15:797.
Van Snick, J. et al. (1990) Annu. Rev. Immunol. 8:253.
Northemann, W. et al. (1989) J. Biol. Chem. 264:16072.
Van Snick, J. et al. (1988) Eur. J. Immunol. 18:193.
Van Snick, J. et al. (1986) Proc. Natl. Acad. Sci. USA 83:9679.
Cayphas, S. et al. (1987) J. Immunol. 139:2965.