Fig. 2.— Expression of manganese superoxide dismutase (MnSOD) in the epithelium of central bronchus, peripheral bronchiolus, blood vessels, alveolar epithelial cells and alveolar macrophages in nonsmokers (□), smokers with normal lung function (▪) and smokers with chronic obstructive pulmonary disease (COPD; └). Immunoreactivity was assessed from the biopsies of 13 nonsmokers, 20 smokers and 22 smokers with COPD. Data are presented as mean±sem. #: p=0.041, nonsmokers versus smokers with COPD; ¶: p=0.01, nonsmokers versus smokers with COPD; +: p=0.022, nonsmokers versus smokers with normal lung function.