Altered airway surfactant phospholipid composition and reduced lung function in asthma

Pulmonary surfactant in bronchoalveolar lavage fluid (BALF) and induced spu tum from adults with stable asthma (n = 36) and healthy controls (n = 12) w as analyzed for phospholipid and protein compositions and function. Asthmat ic subjects were graded as mild, moderate, or severe. Phospholipid composit ions of BALF and sputum from control subjects were similar and characterist ic of surfactant. For asthmatic subjects, the proportion of dipalmitoyl pho sphatidylcholine (16:0/16:0PC), the major phospholipid in surfactant, decre ased in sputum (P < 0.05) but not in BALF.(1) In BALF, mole percent 16:0/16 :OPC correlated with surfactant function measured in a capillary surfactome ter, and sputum mole percent 16:0/16:OPC correlated with lung function (for ced expiratory volume in 1 s). Neither surfactant protein A nor total prote in concentration in either BALF or sputum was altered in asthma. These resu lts suggest altered phospholipid composition and function of airway (sputum ) but not alveolar (BALF) surfactant in stable asthma. Such underlying surf actant dysfunction may predispose asthmatic subjects to further surfactant inhibition by proteins or aeroallergens in acute asthma episodes and contri bute to airway closure in asthma. Consequently, administration of an approp riate therapeutic surfactant could provide clinical benefit in asthma.