BAL fluid contains detectable superoxide dismutase 1 activity

Objective: This study determined which, if any, of the three superoxide dismutase (SOD) enzyme activities were detectable in BAL fluid (BALF). Background: The identity and concentrations of antioxidant molecules in BALF have not been fully characterized. One important class of antioxidants is that of the SOD enzymes. Methods: BALF from control nonsmokers (n=9), smokers (n=7), and asthmatic subjects (n=12) were examined for SOD activity by a modified pyrogallol auto-oxidation method. The particular SOD enzyme or enzymes responsible for any activity were identified based on activity inhibition data and gel filtration column chromatography patterns. Results: SOD activity was detected in all samples. Unlike serum or some other fluids, in which the enzyme extracellular SOD accounts for virtually all SOD activity, the enzyme SOD 1 accounted for virtually all SOD activity. BALF SOD activities were lower for smokers than for control or asthmatic subjects (p<0.05). Conclusion: BALF SOD 1 activities can be measured as part of lung antioxidant studies. Data from a limited number of subjects suggested that smokers can have low BALF SOD values.