IL5, also known as interleukin-5, is a member of the hematopoietin receptor superfamily and is comprised of a cytokine-specific alpha chain and the common beta chain that is shared among these cytokines for signaling. It related hematopoietic cytokines that are important for allergic inflammation. It is a lineage-specific cytokine for eosinophilpoiesis and plays an important part in diseases associated with increased eosinophils, such as asthma. Recombinant human IL5, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.