Histological sections of airways from rats chronically challenged with phosphate-buffered saline (PBS), treated with control ascites (PBS/Cont group), rats chronically challenged with ovalbumin (OVA), treated with control ascites (OVA/Cont group) and rats chronically challenged with OVA, treated with OX-8 monoclonal antibody (OVA/OX-8 group). Periodic acid–Schiff staining for the detection of mucus-containing cells (a–c), proliferating cell nuclear antigen immunohistochemistry for the detection of proliferating epithelial cells (d–f), and α-smooth muscle actin immunohistochemistry for the detection of airway smooth muscle (g–i) in rat airways.