Evaluation of airway inflammation using induced sputum in adult patients with bronchial asthma

Nam, Eon Jeong; Lee, Jong Myung; Kim, Gun Woo; Kim, Shin Woo; Kim, Nung Soo

Abstract

OBJECTIVES
This study was performed to investigate the relationship between cell counts, supernatant and lysate ECP levels in sputum, and physiologic markers in adult asthmatics.
METHODS
Twenty-two patients with mild to moderate persistent asthma, ten patients with acute exacerbated asthma and nine healthy subjects were enrolled. Sputum was induced by inhalation of hypertonic saline, and homogenized with 0.1% dithiothreitol. A total and differential cell was measured. The remnant cell suspension was centrifuged, and ECP (supernatant ECP) was measured in supernatant fluid. Cell pellet was reacted with a cellular lysis buffer to release cell-associated ECP, and ECP (lysate ECP) was measured again in supernatant fluid. The ratio of supernatant to lysate ECP was calculated as an index of eosinophil degranulation. Spirometry and methacholine bronchial challenge tests were also performed as physiological markers of asthma.
RESULTS
The patients with acute exacerbated asthma showed significantly higher percentage of sputum neutrophil, eosinophil count, concentration of sputum supernatant ECP and ratio of supernatant to lysate ECP than those of normal controls and stable asthmatic patients(p < 0.05, respectively). The level of sputum supernatant ECP, supernatant/lysate ECP ratio, and percentage of neutrophil showed negative correlations with pulmonary functions, but no correlations with a degree of bronchial hyperresponsiveness. There was no significant correlations between of serum ECP level and physiological parameters.
CONCLUSION
These results suggest that both neutrophils and eosinophils play roles in the exacerbation of asthma. The sputum supernatant/lysate ECP ratio might be valuable in assessment of activation status of eosinophils in various hypereosinophilic conditions or diseases.