IL-6 is produced by T cells, monocytes, fibroblasts, endothelial cells and keratinocytes. It is responsible for the stimulation of B cell differentiation, the development of megakaryocytes, production of platelets, and regulation of bone metabolism.  Recombinant Human Interleukin-6 (rHu IL-6) produced in E. coli is a single, non-glycosylated polypeptide chain that contains 184 amino acids and has a molecular mass of 21 kDa.