IFN-γ plays key roles in the development of AHR and non-eosinophilic lung inflammation in the murine model of Th2 type asthma. For all figures, evaluation (n = 5 each group) was performed after allergen challenge. *, P < 0.05 compared to mice sensitized with PBS; **, P < 0.05 versus the other groups. (A) Methacholine AHR in IFN-γ-/- and WT (BALB/c) mice 24 h after the last allergen challenge. (B) BAL cellularity (left panel) and representative lung histology in IFN-γ-/- and WT (BALB/c) mice 48 h after the last allergen challenge. (H&E staining, original magnification ×400). a, WT_PBS; b, IFN-γ-/-_PBS; c, WT_OVA/alum; d, IFN-γ-/-_OVA/alum. (C) BAL IP-10 (left panel) and TGF-β1 (right panel) levels in IFN-γ-/- and WT control mice 48 h after the last allergen challenge. (D) BAL IL-12 (left panel) and IL-13 (right panel) levels in IFN-γ-/- and WT control mice 6 h after three rounds of allergen challenge.