Th2 responses in the STAT6KO Treg-of-B (P) group, including OVA-specific IgE and IgG1, IL-5 produced by splenocytes, eotaxin in BALF, airway hyperresponsiveness and infiltrated eosinophilia in BALF, were all comparable with those in the asthma group. Here, IL5 is linked to asthma.