The mouse anti-human IL-4 monoclonal antibody (clone 5B5) is of the IgG1 substype. The 5B5 antibody binds with high efficiency to natural and recombinant human IL-4.and possesses neutralizing activity. Further, the 5B5 antibody is effective in ELISA systems and is applicable in immunohistochemistry (van der Pouw Kraan, T. et al. 1993 and Boven L.A. et al. 2006).