The Rat IL-6 ELISA Test Kit is designed for quantitative determination of the concentration of rat interleukin 6 (IL-6) in serum, plasma, and cell culture supernatant. Rat interleukin 6 (IL-6) contains 187 amino acid residues after cleavage of a signal peptide of 24 amino acids. It is a multifunctional cytokine that plays important roles in host defense, acute phase reactions, immune responses, nerve cell functions and hemotopoiesis. IL-6 is expressed by a variety of normal and transformed lymphoid and nonlymphoid cells. The production of IL-6 is up-regulated by numerous signals such as mitogenic or antigenic stimulation, lipopolysaccharides, calcium ionophores, cytokines and viruses. IL-4, IL-10 and IL-3 inhibit IL-6 expression in monocytes. Elevated serum IL-6 levels have been observed in a number of pathological conditions, including bacterial and viral infections, trauma, autoimmune diseases, inflammations and malignancies. At the protein sequence level, there is approximately 39% identity between rat and human IL-6, and 87% identity between mouse and rat IL-6.