A double-blind study on the effect of inhaled corticosteroids on plasma protein exudation in asthma

Plasma protein exudation into the airways is an important pathophysiologica l event in asthma. The effect of 12 wk of treatment with inhaled fluticason e propionate (FP; 250 mu g twice a day) or salbutamol (Sb; 400 mu g twice a day) on plasma protein leakage was compared in a double-blind, randomized parallel-group study of 30 patients with asthma. Primary outcomes were plas ma protein leakage and size selectivity of the blood-airway lumen barrier, cell differentials in BAL fluid, and bronchial responsiveness to histamine (PC(20)histamine). Two independent procedures to account for the effect of variable dilution of BAL on the levels of albumin (Alb) and alpha(2)-macrog lobulin (A2M) in BAL fluid consisted of correction based on urea levels and on the application of the relative coefficient of excretion [RCE = ([A2M] in BAL fluid/[A2M] in serum)/([Alb] in BAL fluidl[Alb] in serum)]. In the F P group a significant decrease was found in the A2M level and the RCE, and in the percentage of eosinophils in BAL fluid. The PC(20)histamine increase d significantly (mean increase, 2.4 doubling doses), whereas PC(20)histamin e decreased in the Sb group. Differences between groups were significant ex cept for the decrease in eosinophils. We conclude that 12 wk of FP (250 mu g twice a day) decreased the permeability of the blood-airway lumen barrier , in particular for high molecular weight proteins.