Comparison of sputum induction with bronchoalveolar lavage cell differential counts in patients with sarcoidosis

Background and aim: Induced sputum (IS) has been proposed as a useful non-invasive method mainly for the assessment of airway diseases. The aim of this study was to evaluate IS cellular composition and T-lymphocyte subpopulations and to compare them with those of bronchoalveolar lavage fluid (BALF) in patients with sarcoidosis. Methods: We studied prospectively 20 patients (12 female, 8 male) of median age 46 yr (range 25-65) with sarcoidosis and 10 normal subjects (5 female, 5 male) of median age 39 yr (range 26-60). IS was performed with hypertonic saline solution using an ultrasonic nebulizer (De Vilbis 2000). BALF was performed by conventional procedure using fiberoptic bronchoscopy. May-Giemsa-Grunewald stained preps were differentially counted and T-lymphocyte subsets were analyzed by flow activated cell sorter (FACS). Results: The percentage of macrophages was significantly lower in IS than in BALF (p < 0.0001), the percentage of neutrophils was significantly lower in BALF than in IS (p < 0.0001), while there was no difference in the percentage of lymphocytes (p = 0.693) and eosinophils (p = 0.25) in IS vs BALF in patients with sarcoidosis. A significant correlation was found between BALF and IS lymphocyte counts (r = 0.61, p = 0.004), macrophages (r = 0.51, p = 0.02), and CD4(+)/CD8(+) ratio (r = 0.700, p = 0.001). Conclusions: These results suggest that the inflammation in sarcoidosis could be effectively and non-invasively determined by the analysis of cell differential counts and T-lymphocyte subsets in IS. Further studies are needed to explore the role of IS vs BALF in the follow-up of these patients.