Induced sputum and bronchoalveolar lavage as tools for evaluating the effects of inhaled corticosteroids in patients with asthma

Changes in airway inflammation can be studied with bronchoalveolar ravage, but the widespread use of this procedure is limited by its invasiveness. Th e aim of this study was to evaluate the usefulness of induced sputum as a n an-invasive alternative to bronchoalveolar lavage for studying changes in a irway inflammation in patients with asthma. Thirty patients were treated fo r 12 weeks with an inhaled corticosteroid (fluticasone propionate (FP), 250 mu g twice daily) or a short-acting beta-agonist (salbutamol (Sb), 400 mu g twice daily) in a double-blind, double-dummy, randomized parallel group s tudy. Sputum induction with hypertonic saline solution was performed twice before treatment and after 4, 8, 10, and 11 weeks of treatment. Bronchoalve olar lavage fluid divided into two pools (first 60 mL portion as bronchoalv eolar lavage/bronchial wash (BAL/BW) and subsequent 80 mt as bronchoalveoal ar lavage (BAL)) was obtained before and after 12 weeks of treatment. Chang es in cell differentials and plasma-protein leakage (alpha(2)-macroglobulin , albumin, and their ratio (relative coefficient of excretion, RCE)) were a nalyzed in induced sputum and were compared with changes in BAL/BW and BAL. During treatment with FP, the PC(20)histamine (interpolated concentration of histamine that caused a fall in FEV1 of 20% of the baseline value) incre ased (P < .0001), and the percentage of eosinophils (P = .004), levels of c cs-macroglobulin (P = .09) and RCE (P = .007) decreased in sputum. These ch anges were different from those in the Sb group (PC(20)histamine P < .0001, eosinophils P = .004, alpha(2)-macroglobulin P = .003, RCE P = .01), in whi ch alpha(2)-macroglobulin showed a significant increase (P = .015). Changes in the percentage of eosinophils and in the levels of alpha(2)-macroglobul in in sputum were associated with changes in the PC(20)histamine (Rs = -0.5 9, P = .007 and Rs = -0.47, P = .03, respectively). These correlations did not reach significance in BAL/BW and BAL fluid. The statistical power to de tect changes in induced sputum was higher for the percentage of eosinophils and similar for plasma protein leakage as compared with analysis of BAL/BW and BAL fluid. We conclude that the analysis of induced sputum is a useful , non-invasive alternative to bronchoalveolar lavage for assessing the effe cts of antiinflammatory drugs in asthma.