Ceruloplasmin. Increased serum concentration and impaired antioxidant activity in cigarette smokers, and ability to prevent suppression of elastase inhibitory capacity of alpha 1-proteinase inhibitor.

Bronchoalveolar lavage fluid of smokers and nonsmokers contains significant concentrations of ceruloplasmin, the major serum inhibitor of lipid peroxidation, with limited superoxide dismutase activity. This suggested that ceruloplasmin may protect the lower respiratory tract against oxidant(s) in cigarette smoke and air pollutants. We investigated (1) serum ceruloplasmin concentration and antioxidant activity (percentage inhibition of autoxidation of ox-brain homogenate) in healthy male and female smokers and nonsmokers, and (2) the capacity of ceruloplasmin to prevent suppression of the elastase inhibitory capacity of alpha 1-proteinase inhibitor by the oxidant chloramine T and by cigarette smoke solution. Mean ceruloplasmin concentration was 18% higher in 35 female smokers than in 46 male smokers (p less than 0.001), 17% higher in 22 female nonsmokers than in 18 male nonsmokers (p less than 0.005), 15% higher in the female smokers than in the female nonsmokers (0.02 greater than p greater than 0.01), and 14% higher in the male smokers than in the male nonsmokers (p less than 0.001). Serum antioxidant activity showed significant linear correlations with serum ceruloplasmin in smokers and nonsmokers of both sexes; correlation coefficients, all significant, ranged from 0.65 to 0.50. For comparable ceruloplasmin concentrations, serum antioxidant activity was significantly lower in smokers (males: 9%, p less than 0.001; females: 7%, 0.05 greater than p greater than 0.01) than in nonsmokers. There was a linear relationship between ceruloplasmin concentration and its ability to prevent suppression of the elastase inhibitory capacity of alpha 1-proteinase inhibitor by chloramine T and cigarette smoke solution. Our findings indicate: (1) that cigarette smoking can cause partial inactivation of serum antioxidant activity accompanied by insufficient compensatory increase in ceruloplasmin concentration, and (2) that ceruloplasmin may protect the lung against oxidant(s) in cigarette smoke and air pollutants.