Airway mucosal permeability in chronic bronchitics and bronchial asthmatics with hypersecretion

To determine airway mucosal permeability, radiolabeled albumin in sputum was examined on the basis of a 2-h period of sputum collection for as long as 8h after intravenous administration of 131I-labeled human serum albumin. This technique was applied to 12 patients with bronchial asthma associated with hypersecretion or chronic bronchitis. Group A consisted of 6 asthmatics (2 females and 4 males, 56.0 +/- 6.4 yr of age, mean +/- SEM); Group B consisted of 6 bronchitics (3 females and 3 males, 53.8 +/- 6.5 yr of age). Between Groups A and B, there was no significant difference in sputum volume per day or in obstructive impairment. Radiolabeled albumin concentration (cpm/ml) was obtained from radiocount of each sputum sample and then divided by serum concentration at the time of each sampling (2, 4, 6, and 8 h after administration). Group B showed large values compared with those in Group A. In Group A, the ratios were 2.0 +/- 0.8, 2.5 +/- 0.5, 2.2 +/- 0.2, and 1.5 +/- 0.4% (mean +/- SEM) at 2, 4, 6, and 8 h after the administration, respectively, whereas in Group B, the ratios were 3.0 +/- 0.6, 7.0 +/- 1.8, 7.2 +/- 1.8, and 7.4 +/- 2.4%, respectively. The differences between Groups A and B were statistically significant (two-way analysis of variance). These findings suggest that an increase in airway mucosal permeability is due to mucosal epithelial damage by chronic inflammation in bronchitics and not to the underlying abnormality of asthma.