Inflammatory reaction and airway damage in cystic fibrosis.

In cystic fibrosis there is chronic infection and inflammatory reaction in the 
airways, accompanied by destruction and shedding of airway epithelium. Leukocytes migrate 
into the airways and some disintegrate, liberating deoxyribonucleoprotein that is incorporated 
into the gel structure of the bronchial mucus. We compared the 
status of these processes in cystic fibrosis with that in chronic 
bronchitis and bronchiectasis, by examining the sputum raised from the lower 
airways. Measurements also were made on sputum induced in normal subjects. 
The results indicate that migration of leukocytes into the airways and 
shedding of damaged airway epithelium were minimal in the normal subjects; 
they were significant in the patients with chronic bronchitis, higher in 
those with bronchiectasis, and still higher in those with cystic fibrosis. 
The large increases found in the total content of DNA and 
solids in the cystic fibrosis sputum were due to increases in 
the insoluble fraction containing the whole leukocytes and particulate debris that 
remained when the sputum mucus gel was solubilized with mercaptoethanol. Despite 
the large increases in the total content of DNA and solids, 
the contents of mucus gel components and of deoxyribonucleoprotein from disintegrated 
leukocytes actually present in the mucus gel structure of the cystic 
fibrosis sputum were not significantly higher than in the sputum from 
the patients with chronic bronchitis or brochiectasis. 