Interleukin-6 and its relation to inflammation and disease.

Interleukin-6 (IL-6) is a multifunctional cytokine that regulates the immune response, acute phase reactions, and hematopoiesis. Its receptor system consists of two molecules: a ligand-binding 80-kDa molecule and a non-ligand-binding signal transducer, gp 130, both of which were found to belong to the cytokine receptor family. Deregulated IL-6 gene expression has been implicated as being involved in the pathogenesis of a number of diseases, especially autoimmune diseases and plasma cell neoplasias. In fact, IL-6 transgenic C57BL/6 mice showed a massive polyclonal plasmacytosis with production of autoantibodies and mesangial proliferative glomerulonephritis, indicating that IL-6 plays a critical role in the development of plasma cell abnormalities and glomerulonephritis.