Dysfunction of pulmonary surfactant in asthmatics after segmental allergenchallenge

Increased airway resistance in asthma may be partly due to poor function of pulmonary surfactant. This study investigated the inflammatory changes of bronchoalveolar lavage fluid (BALF) and the performance of BALF surfactant in healthy control subjects (n = 9) and patients with mild allergic asthma (n = 15) before and after segmental challenge. BALF was obtained for baseli ne values, and 24 h after challenge with saline solution in one lung segmen t and with allergen in another. Cell counts, phospholipid and protein conce ntrations, and ratios of small to large surfactant aggregates (SA/LA) were analyzed. Surface tension was determined with a pulsating bubble surfactome ter, and the ability of the BALF surfactant to maintain airway patency was assessed with a capillary surfactometer. Baseline values of control subject s and asthmatics were not different. Challenge with saline and antigen rais ed total inflammatory cells in both control subjects and asthmatics. Allerg en challenge of asthmatics, but not of healthy volunteers, significantly in creased eosinophils, proteins, SA/LA, and surface tension at minimum bubble size, and diminished the time the capillary tube is open. In conclusion, a llergen challenge in asthmatics induced surfactant dysfunction, probably ma inly because of inhibiting proteins. During an asthma attack, narrow conduc ting airways may become blocked, which might contribute to an increased air way resistance.