Tracheobronchial clearance in asthma-discordant monozygotic twins.

Tracheobronchial clearance and bronchial reactivity were studied in 6 asthma-discordant monozygotic twin pairs, and in 3 concordant pairs as controls. Clearance of 6-microns Teflon particles labeled with 99mTc was followed for 2 h. The results indicate that clearance in the larger airways is usually not severely impaired in mild to moderate asthma, and that it may be increased as well as decreased. Bronchial reactivity correlated with clearance in the nonasthmatics.