Description: Human IL-6 (also known as B Cell Stimulating Factor BCSF, BSF-2) is a ~21-28 kDa factor produced by a variety of cell types including monocytes, fibroblasts and endothelial cells. Upon stimulation, macrophages, T, B, mast, glial cells, eosinophils, keratinocytes and granulocytes also secrete IL-6. This pleiotrophic cytokine influences antigen-specific immune response, inflammatory response, and the development of neurons and is a major mediator of the acute phase reaction.