Serum surfactant protein-A levels in chronic bronchitis and its relation to smoking.
BACKGROUND
Surfactant protein-A (SP-A), which is an important constituent of natural surfactant, occurs physiologically in small amounts in blood. Tobacco smoke induces increased alveolo-capillary leakage of surfactant proteins into blood and its level in blood may help in the assessment of lung injury caused by smoke. Little is known on the SP-A levels in patients with chronic obstructive pulmonary disease (COPD).


METHODS
Prospective analytical study of 30 patients with clinical diagnosis of chronic bronchitis, which was made on the basis of symptoms, signs and chest radiographic findings. Serum SP-A and serum cotinine levels were measured.


RESULTS
Out of 30 patients, 21 were smokers and nine were non-smokers. The serum SP-A level in smokers with chronic bronchitis is significantly higher than the non-smokers. The plasma cotinine levels are also high in smokers. However, there was no correlation between the serum SP-A level and plasma cotinine level (r=0.044). Serum SP-A levels were related to age in smokers (r=0.566, p<0.01) but not in non-smokers with chronic bronchitis (r=0.017, p>0.05).


CONCLUSIONS
The increase in SP-A level in smokers with chronic bronchitis suggests that tobacco smoking causes a chronic increase in permeability of the lung parenchyma. The SP-A, a lung-specific secretory protein, is a potential marker for non-invasive assessment of the integrity of the lung epithelium. Further studies are required to find out whether SP-A can be used as a marker for early identification of smokers who are at risk of COPD.
Behera
D
D
Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India. dbehera@glide.net.in
Balamugesh
T
T
Venkateswarlu
D
D
Gupta
Arti
A
Majumdar
S
S
D000367:Age Factors; D029481:Bronchitis, Chronic / Q000097:blood*; D003367:Cotinine / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood; D037662:Pulmonary Surfactant-Associated Protein A / Q000097:blood*; D012907:Smoking / Q000097:blood*; D018709:Statistics, Nonparametric
D037662:Pulmonary Surfactant-Associated Protein A; D003367:Cotinine