[Surfactant protein A in bronchoalveolar lavage fluid from patients with idiopathic interstitial pneumonia]

We measured the levels of surfactant protein A (SP-A) in bronchoalveolar lavage fluid from patients with idiopathic interstitial pneumonia and from healthy volunteers. The SP-A levels in the patients who were smokers (1.4 +/- 0.2 micrograms/ml) were significantly (p < 0.05) lower than those in the patients who were nonsmokers (3.0 +/- 0.5 micrograms/ml). However, SP-A levels did not differ significantly between patients and volunteers who were smokers, or between patients and volunteers who were nonsmokers. The ratios of SP-A to phospholipid in patients who were smokers and in those who were non-smokers did not differ significantly from those in volunteers who were smokers and volunteers who were non smokers. The total number of alveolar macrophages in bronchoalveolar lavage fluid did not significantly correlate with the level of SP-A, although the percentage of alveolar macrophages correlated negatively (p < 0.05) with the level of SP-A. The low level of SP-A in patients with idiopathic interstitial pneumonia who are smokers may weaken the host defense functions in peripheral airways and may contribute to the poor outcomes in these patients.