Inflammatory cytokine levels in induced sputum and bronchoalveolar lavage fluid in pulmonary sarcoidosis

BACKGROUND: The immune inflammatory process in patients with sarcoidosis is not only compartmentalized within the alveolar walls, but also involves the bronchial airways. Analysis of induced sputum has been used as a non-invasive tool for investigating the airways and may reflect the endobronchial and parenchymal inflammation in patients with sarcoidosis. This present study was designed to measure the soluble pro-inflammatory cytokine levels interleukin-1 (IL-1), interleukin-6 (IL-6), tumuor necrosis factor-alpha (TNF-alpha) and percentage of macrophages expressing these cytokines in induced sputum and bronchoalveolar lavage (BAL) fluid in patients with pulmonary sarcoidosis. METHODS: Sputum induction and BAL was carried out in 27 patients with newly diagnosed sarcoidosis. Control group consisted of six patients with a normal chest radiograph (three patients with carcinoma esophagus and three patients with doubtful history of hemoptysis). Induced sputum was also obtained from 10 non-smoking, non-atopic healthy controls. RESULTS: Percentage of macrophages expressing pro-inflammatory cytokines and soluble cytokine levels in induced sputum were higher in patients with sarcoidosis compared to both groups of controls. There was good correlation between IL-6 and TNF-alpha levels (r = 0.49, 0.58 p < 0.05) and percentage of macrophages expressing all three cytokines (r = 0.56-0.71, p < 0.01) between induced sputum and BAL fluid. Mild positive correlation between cytokine levels in sputum and age was also noted (r = 0.33-0.38, p < 0.05). CONCLUSIONS: Induced sputum may reflect changes in cytokine milieu in BAL in sarcoidosis.