Rat IL- 17A (IL-17), also known as CTLA-8, is a proinflammatory cytokine member of a six-species family of proteins (IL-17A-17F). Rat IL-17A protein is a homodimer consisting of two 134 amino acids peptides. IL-17A is secreted mainly by activated CD4+ and CD8+ T lymphocytes and acts through its receptor, IL-17R, to induce the expression of many mediators of inflammation, most strikingly, those that are involved in the proliferation, maturation and chemotaxis of neutrophils. Elevated levels of IL-17A have been associated with several conditions, including rheumatoid arthritis, airway inflammation, allograft rejection, inflammatory bowel disease, psoriasis, cancer and multiple sclerosis. There is 58% identity between the amino acid sequence of human and rat IL-17A. Recombinant rat IL-17A produced in E.coli is a non-glycosylated disulfide-joined homodimer having a molecular mass of 30.0 kDa.