HO-1 overexpressing mice are protected against pulmonary inflammation induced by hypoxia. ( a ) Immunostaining for neutrophils and macrophages. Frozen lung sections from Tg or non-Tg control mice that had been exposed to hypoxia for 48 h were stained with anti-Ly-6G antibody for neutrophils and anti-Mac-3 antibody for macrophages (brown staining). Original magnification: ×100. ( b ) The number of neutrophils and macrophages in BAL fluid after hypoxia. Differential cell counts for neutrophils (Neut, Upper ) and macrophages (Mac, Lower ) were performed in the BAL fluid of Tg (closed bars) and non-Tg control mice (open bars) after 48 h of hypoxia. Data are expressed as mean ± SEM ( n = 4). *, P