Animal-free Recombinant Human IL-6 is produced in human 293 cells as a monomeric glycoprotein with an apparent molecular mass of 21 to 29 kDa. This broad molecular mass is attributable to glycosylation, which is absent when this cytokine is expressed in E. coli. Glycosylation contributes to stability in cell growth media and other applications. IL-6 is a pleiotropic cytokine that plays an important role in host defense by regulating immune and inflammatory responses. Produced by T cells, monocytes, fibroblasts, endothelial cells, and keratinocytes, IL-6 has diverse biological functions.