Interleukin-5 (IL-5) is a 40 kDa secreted, heparin-binding, disulfide-linked homodimeric glycoprotein that belongs to the alpha -helical group of cytokines. It promotes the proliferation, differentiation and activation of eosinophils. The 115 amino acid (aa) mature feline IL-5 shares 70% and 59% aa sequence identity with human and mouse IL-5, respectively. The IL-5 receptor is a complex of an IL-5-specific ligand-binding alpha subunit with a signal transducing common beta subunit ( beta c) that is shared with receptor complexes for IL-3 and GM-CSF.
