Smoking versus infection as the aetiology of bronchial mucous gland hypertrophy in chronic bronchitis.

The smoking habits of 50 proved cases of chronic bronchitis were studied. Bronchoscopy was done and a bronchial biopsy was taken for histological examination. Bronchial lavage was obtained under sterile conditions for bacteriological studies. The degree of bronchial mucous gland hypertrophy was determined, and the presence or absence of infection, as shown by the presence of potential pathogens in the bronchial lavage, was noted. We think that tobacco smoking and its resulting irritation to the bronchi is the most important underlying cause of bronchial mucous gland hypertrophy because there is: (1) a significantly higher incidence of mucous gland hypertrophy in smokers than in non-smokers among the 50 chronic bronchitics studied; (2) a significantly higher accumulated lifetime tobacco consumption in patients exhibiting mucous gland hypertrophy than in those without hypertrophy of the bronchial mucous glands; (3) a significant association and correlation between the degree of mucous gland hypertrophy and the intensity of smoking; and (4) no difference in the comparative frequency of occurrence of bronchial mucous gland hypertrophy in subjects with and without demonstrable infection, as shown by the presence of potential pathogens in the bronchial lavage. We could not deny that infection might be having an initiating or potentiating effect.