Elevated surfactant protein A in bronchoalveolar lavage fluids from sarcoidosis and hypersensitivity pneumonitis patients.

Interstitial lung diseases often are accompanied by histopathologic evidence of alveolar type 2 cell alterations. In the alveolar milieu, the surfactant-specific protein A (SP-A) is a secretory product of alveolar type 2 cells. Therefore, we measured SP-A levels in bronchoalveolar lavage (BAL) fluids from patients with untreated sarcoidosis (n = 35) and hypersensitivity pneumonitis (HP [n = 10]) and compared the results with those from 21 healthy control subjects. In sarcoidosis patients, SP-A was markedly higher than in control subjects with a mean of 8.0 micrograms/ml of recovered BAL fluid +/- 0.7 SEM (p < 0.0001 compared with control subjects). In HP, SP-A values were comparable with those in sarcoidosis with a mean of 9.0 micrograms/ml +/- 1.7 SEM. Mean SP-A in the control group was 4.0 micrograms/ml +/- 0.3 SEM. These results suggest that SP-A secretion is stimulated in sarcoidosis and HP. Further studies seem justified to investigate the role of the surfactant system in interstitial lung diseases as well as the potential clinical usefulness of SP-A measurements in BAL.