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 lavage, but the widespread use of this procedure is limited by its invasiveness. The aim of this study was to evaluate the usefulness of induced sputum as a non-invasive alternative to bronchoalveolar lavage for studying changes in airway inflammation in patients with asthma. Thirty patients were treated for 12 weeks with an inhaled corticosteroid (fluticasone propionate [FP], 250 μg twice daily) or a short-acting beta-agonist (salbutamol [Sb], 400 μg twice daily) in a double-blind, double-dummy, randomized parallel group study. Sputum induction with hypertonic saline solution was performed twice before treatment and after 4, 8, 10, and 11 weeks of treatment. Bronchoalveolar lavage fluid divided into two pools (first 60 mL portion as bronchoalveolar lavage/bronchial wash [BAL/BW] and subsequent 80 mL as bronchoalveoalar lavage [BAL]) was obtained before and after 12 weeks of treatment. Changes in cell differentials and plasma-protein leakage (α2-macroglobulin, albumin, and their ratio [relative coefficient of excretion, RCE]) were analyzed in induced sputum and were compared with changes in BAL/BW and BAL. During treatment with FP, the PC20histamine (interpolated concentration of histamine that caused a fall in FEV1 of 20% of the baseline value) increased (P