Recombinant Feline IL-6Interleukin-6 (IL-6) is an interleukin that acts as both a pro-inflammatory and anti-inflammatory cytokine. It is secreted by T cells and macrophages to stimulate immune response to trauma, especially burns or other tissue damage leading to inflammation. IL-6 is also produced from muscle, and is elevated in response to muscle contraction. It is significantly elevated with exercise, and precedes the appearance of other cytokines in the circulation. Osteoblasts secrete IL-6 to stimulate osteoclast formation. Smooth muscle cells in the tunica media of many blood vessels also produce IL-6 as a pro-inflammatory cytokine. The role of IL-6 as an anti-inflammatory cytokine is mediated through its inhibitory effects on TNF-alpha and IL-1, and activation of IL-1ra and IL-10. The biological activity of recombinant feline IL-6 was measured in a cell proliferation assay using the mouse B9 cell line. The ED50 for this effect is typically 10-20 pg/mL. The biological activity was also measured in 7TD1 cells. The ED50 for this effect is typically 0.2-0.3 ng/mL.