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. This evidence concerns the gene IL5 and airway hyperresponsiveness.