Evidence for eosinophil activation in bronchiectasisunrelated to cystic fibrosis and bronchopulmonary aspergillosis:discrepancy between blood eosinophil counts and serum eosinophilcationic protein levels

BACKGROUND—Increased serum levelsof eosinophil cationic protein (ECP) have been detected in adolescentpatients with cystic fibrosis. However, ECP concentrations in adultpatients with bronchiectasis unrelated to cystic fibrosis have not been studied.
METHODS—Eosinophil numbers and serumconcentrations of ECP were determined in 14 patients with known ornewly diagnosed bronchiectasis and compared with age and sex matchedpatients with allergic bronchial asthma, chronic obstructive pulmonarydisease (COPD), and controls in whom bronchiectasis or obstructivepulmonary disease could be excluded.
RESULTS—Serum ECP levels were significantlyraised both in patients with bronchiectasis (median (range) 22.5 µg/l(7-85)) and allergic asthma (35.0 µg/l (7-128)) compared with thesex and age matched subjects suffering from COPD (6.7 µg/l (1.5-28);p<0.006) and non-obstructive normal controls (7.5 µg/l (3.5-19);p<0.003). In contrast, significantly increased peripheral eosinophilnumbers were observed in patients with bronchial asthma (305 × 10⁶/l; p<0.01) but not in those with bronchiectasis(10² × 10⁶/l), COPD (117 × 10⁶/l), and healthy controls (101 × 10⁶/l).
CONCLUSIONS—The discrepancy betweeneosinophil counts and eosinophil numbers in patients withbronchiectasis suggests that serum ECP levels may be more relevant inassessing local eosinophil involvement than blood eosinophil numbers.