Nitric oxide metabolites, eosinophils, eosinophil cationic protein, EG2+ eosinophils in sputum according to asthma severity

Jang, An Soo; Choi, In Seon

Abstract

BACKGROUND: Eosinophils play an important role in asthmatic airway inflammation collaborateing with other inflammatory cells. Nitric oxide (NO) may amplify and perpetuate allergic inflammation.
OBJECTIVE
The present study was aimed to determine whether NO metabolites and eosinophil activation markers in sputum reflect the severity of asthma.
METHODS
Sputum was obtained in 27 asthmatic patients. We processed freshly expectorated sputum separated from saliva and by a treatment with equal volume of dithiothreitol 0.1%, cytospins for cell count and special stain, we collected the supernatant for biochemical assay. We used immunocytochemical staining to detect EG2+ eosinophils, and fluoroimmunoassay to detect eosinophil cationic protein (ECP). NO metabolites were assayed by using modified Griess reaction.
RESULTS
Moderate and severe asthmatic patients had a significantly higher proportion of eosinophils (37.9+/-7.8% vs 58.4+/-7.9% vs 8.9+/-2.0%, p<0.01) and lower proportion of macrophages (46.5+/-5.5% vs 18.1+/-4.6% vs 75.6+/-4.0%, p<0.01) compared to mild asthmatics. The proportion of EG2+ eosinophils, and ECP levels in the sputum were significantly higher in moderate and severe asthmatic patients than in mild asthmatic patients (p<0.01, respectively). The level of NO metabolites in the sputum was significantly increased in severe asthmatic patients compared to that in mild asthmatic patients (1372.0+/-168.5micromole/L vs 658.3+/-186.4micromole/L, p<0.05). The proportion of eosinophils in sputum was inversely correlated with FEV1 and FEV1/FVC. EG2+ eosinophils and ECP also had an inverse relationship with FEV1 and FEV1/FVC.
CONCLUSION
These findings demonstrate that the proportion of eosinophils, ECP, EG2+ eosinophils, and NO metabolites in the sputum of patients with asthma may be correlated with asthma severity.