REGIONAL VARIATION IN IRON AND IRON-BINDING PROTEINS WITHIN THE LUNGSOF SMOKERS

The lungs of cigarette smokers are known to contain increased concentr ations of extracellular ferritin-bound iron. Reductants present in cig arette smoke may mobilize alveolar ferritin-bound iron, which could th en promote oxidative injury to lung cells. Because iron-mediated oxida tive injury may be relevant to the pathogenesis of emphysema and lung cancer, which have a predilection for upper lobes, we sought to determ ine whether concentrations of extracellular iron, ferritin, and transf errin differed in upper and lower lobes of cigarette smokers. Bronchoa lveolar lavage (BAL) was performed in the upper and lower lobes of 15 asymptomatic smokers and six healthy nonsmokers. BAL fluid recovered f rom upper robes of smokers contained higher concentrations of iron (p < 0.01) and ferritin (p < 0.006) and lower concentrations of transferr in (p < 0.003) compared with the lower lobes. In contrast, BAL fluid r ecovered from upper and lower lobes of nonsmokers contained much lower concentrations of iron and ferritin, and concentrations were similar in both sites. These findings indicate that, compared with the lower l obes, upper lobes of the lungs of smokers contain higher extracellular concentrations of ferritin-bound iron and decreased concentrations of transferrin. This distribution of lung iron and iron-binding proteins may promote oxidative injury in the upper lobes of smokers.