Induced sputum in systemic sclerosis interstitial lung disease: comparison to healthy controls and bronchoalveolar lavage.

BACKGROUND: Induced sputum (IS) is a noninvasive tool, which can be used to collect cellular and soluble materials from lung airways. OBJECTIVE: To evaluate if IS may be a useful and safe tool for the detection of airway inflammation in patients with interstitial lung disease (ILD) in systemic sclerosis (SSc). METHODS: Sixty-eight patients with SSc and ILD as well as 18 healthy individuals (controls) were selected and submitted to IS examination. In 34 of 68 patients with SSc, bronchoalveolar lavage (BAL) was also performed. Safety of IS was assessed by comparison of forced expiratory volume in the first second (FEV(1)), FEV(1)/forced vital capacity ratio and peak expiratory flow before and after the IS procedure. Cell composition in samples collected by BAL and IS was correlated, and IS total and differential cell count in SSc patients and controls were compared. RESULTS: The total number of cells was significantly higher in IS samples of SSc patients compared to those of healthy controls. Mean percentage of neutrophils was also higher in SSc patients (41.79 +/- 23.89 vs. 27.37 +/- 17.90), as well as lymphocytes (17.42 +/- 19.70 vs. 3.13 +/- 2.28) and eosinophils (2.35 +/- 4.43 vs. 0.41 +/- 0.46). On the other hand, mean percentage of macrophages was higher in healthy individuals (69.10 +/- 19.15 vs. 36.96 +/- 20.68). In fluid recovered by BAL, the most frequent cells were macrophages (67.89% +/- 17.26), while neutrophils (14.77 +/- 17.18%) and lymphocytes (15.62 +/- 13.46%) were less frequent and eosinophils (1.66 +/- 2.08%) were rare. A similar pattern of cell composition was found in IS samples (41.15 +/- 21.67% of macrophages, 39.72 +/- 23.15% of neutrophils, 15.28 +/- 19.46% of lymphocytes and 2.56 +/- 5.03% of eosinophils). Strength of correlation between BAL and IS was significant for macrophages and neutrophils. After IS procedure was performed, improvement of FEV(1) (mean value before IS was 85.09 +/- 14.44 and 88.93 +/- 16.40 after IS) and FEV(1)/forced vital capacity (mean value before IS was 98.53 +/- 12.11 and 105.22 +/- 10.78 after IS) was observed. CONCLUSION: The IS method may allow a noninvasive assessment of cell composition in airway fluid and may contribute to the better understanding of upper/medium airway inflammation in SSc. Future studies are needed to verify whether IS can replace invasive procedures for the detection and monitoring of lung inflammation in SSc.

Interstitial lung disease in systemic sclerosis.

Lung involvement frequently complicates systemic sclerosis (SSc), provoking loss of quality of life and a poor expectation of survival. For this reason an early diagnosis of lung involvement is warranted: high-resolution computed tomography (HRCT), pulmonary function tests (PFT), lung scintigraphy with DTPA and bronchoalveolar lavage (BAL) are mandatory to define and follow-up pulmonary interstitium. Coughing and a sensation of breathlessness on exertion are the earliest symptoms of lung involvement. Lung involvement may be investigated with PFTs, which are non-invasive and require breathing into a tube via a mouthpiece. Forced vital capacity, which measures the total amount of air capable of being blown forcefully, and the diffusion capacity for carbon monoxide, a measure of how well oxygen diffuses into blood, are the most important functional measures. A routine chest X-ray may demonstrate fibrosis, but it is not very sensitive for detecting early or mild disease. For this reason, a HRCT scan is required. This non-invasive investigation provides images of multiple slices through the lung, from top (apex) to bottom (base), and can even detect lung involvement in early phases when no symptoms are present. (99m)T-DTPA is recommended in those patients with isolated diffusion deficits on lung function tests and in addition to HRCT in confirming the suspicion of vascular disease rather than early fibrosing alveolitis. Bronchoscopy with BAL is an invasive test that also may provide information about the inflammatory status of the affected areas of the lung detected during HRCT. In order to detect alveolitis, it should be performed as early as possible, to start prompt immunosuppressive treatment.