Recombinant Human Interleukin-17A/IL-17A produced in E. coli is a single non-glycosylated polypeptide chain containing 133 AAs with a molecular mass of 15,256 Daltons. Interleukin-17 is a potent pro-inflammatory cytokine produced by activated memory T cells. There are at least six members of the IL-17 family in humans and in mice. As IL-17 shares properties with IL-1 and TNF-α, it may induce joint inflammation and bone and cartilage destruction. This cytokine is found in synovial fluids of patients with rheumatoid arthritis, and produced by rheumatoid arthritis synovium. It increases IL-6 production, induces collagen degradation and decreases collagen synthesis by synovium and cartilage and proteoglycan synthesis in cartilage. IL-17 is also able to increase bone destruction and reduce its formation. Blocking of interleukin-17 with specific inhibitors provides a protective inhibition of cartilage and bone degradation.