Objective: This study determined which, if any, of the three superoxid
e dismutase (SOD) enzyme activities were detectable in BAL fluid (BALF
). Background: The identity and concentrations of antioxidant molecule
s in BALF have not been fully characterized. One important class of an
tioxidants is that of the SOD enzymes. Methods: BALF from control nons
mokers (n=9), smokers (n=7), and asthmatic subjects (n=12) were examin
ed for SOD activity by a modified pyrogallol auto-oxidation method. Th
e particular SOD enzyme or enzymes responsible for any activity were i
dentified based on activity inhibition data and gel filtration column
chromatography patterns. Results: SOD activity was detected in all sam
ples. Unlike serum or some other fluids, in which the enzyme extracell
ular SOD accounts for virtually all SOD activity, the enzyme SOD 1 acc
ounted for virtually all SOD activity. BALF SOD activities were lower
for smokers than for control or asthmatic subjects (p<0.05). Conclusio
n: BALF SOD 1 activities can be measured as part of lung antioxidant s
tudies. Data from a limited number of subjects suggested that smokers
can have low BALF SOD values.