IL-6/IL-6 receptor system and its role in physiological and pathological conditions

IL (interleukin)-6, which was originally identified as a B-cell differentiation factor, is a multifunctional cytokine that regulates the immune response, haemopoiesis, the acute phase response and inflammation. IL-6 is produced by various types of cell and influences various cell types, and has multiple biological activities through its unique receptor system. IL-6 exerts its biological activities through two molecules: IL-6R (IL-6 receptor) and gp130. When IL-6 binds to mIL-6R (membrane-bound form of IL-6R), homodimerization of gp130 is induced and a high-affinity functional receptor complex of IL-6, IL-6R and gp130 is formed. Interestingly, sIL-6R (soluble form of IL-6R) also binds with IL-6, and the…