Induced sputum in patients with newly diagnosed sarcoidosis: comparison with bronchial wash and BAL

Sarcoidosis is characterized by a diffuse alveolar inflammatory process, although bronchial airways are often involved. This study compares the cellular profiles of induced sputum (IS), bronchial washing (BW), and BAL in newly diagnosed sarcoidosis patients to those in control subjects, and examines whether inflammatory cell counts from IS are correlated with inflammatory cell counts from BW and BAL in sarcoidosis patients.

We recruited 15 untreated patients with stage I and II pulmonary sarcoidosis and 12 healthy volunteers. Sputum was induced with hypertonic saline solution in all individuals. Bronchoscopy was performed on a different occasion in all patients and in five control subjects.

Mean lymphocyte counts in IS, BW, and BAL fluid from sarcoidosis patients were significantly higher than in control subjects (9.4% vs 3.8%, p < 0.05; 12.6% vs 3.9%, p < 0.05; 24.1% vs 2.6%, p < 0.05, respectively). Moreover, total cell count and percentage of epithelial cells in IS were significantly higher in sarcoidosis patients than in control subjects (p < 0.01 and p < 0.05, respectively). In sarcoidosis patients, comparison between different samples showed significantly higher percentages of macrophages in BW and BAL than in IS (p < 0.05 and p < 0.01, respectively), whereas the percentage of neutrophils was higher in IS compared with BW and BAL (p < 0.01 and p < 0.001, respectively). Finally, the percentage of lymphocytes in IS was significantly lower than that in BAL (p < 0.05) but not that in BW.

We demonstrated that, compared with IS in healthy control subjects, IS in untreated pulmonary sarcoidosis patients contains more total cells, lymphocytes, and epithelial cells. Although the relative proportion of inflammatory cells in the three samples differed, lymphocyte counts in IS were high. This finding suggests that IS could be used as a valuable alternative to more conventional invasive techniques in clinical assessment of pulmonary sarcoidosis patients.