EG2 expressed by eosinophils as a clinically useful indicator of asthma

The monitoring of airway inflammation is mandatory for the improved control of bronchial asthma. We previously reported that intracellular EG2 levels of eosinophils, a marker of bronchial asthma increased in asthma patients. In this study, we hypothesized that eosinophil EG2⁺ expression increases during airway inflammation in asthmatic individuals. Eosinophil EG2⁺ and percentage eosinophil EG2⁺ with whole blood flow cytometry, eosinophil counts, serum total IgE, serum eosinophil cationic protein, eosinophil-derived neurotoxin, and percent of forced expiratory volume in 1 second/force vital capacity (FEV₁/FVC) were measured in 33 asthmatic patients and 22 healthy volunteers. The relationships between these markers were evaluated. Comparisons were made on EG2⁺ expression between attack and asymptomatic periods in six asthmatic patients. EG2⁺ expression was significantly greater in the asthmatic patients than in healthy subjects. Furthermore, the EG2⁺ expression showed a significant increase during attacks. EG2⁺ expression inversely correlated with the FEV₁/FVC. These results suggest that EG2⁺ expression may be a useful clinical marker of airway inflammation in asthma.