The Respiratory Burst Activity of Activated Eosinophils in Atopic Asthmatics

Although activated eosinophils in peribronchial tissue and peripheral blood are increased in patients with asthma, the mechanisms contributing to their presence and causing airway hyperreactivity are not well established. Recently, the respiratory burst activity on activated eosinophils can be evaluated by dual staining with monoclonal antibody EG2 and 2,7–dichlorofluorescein diacetate, which can be analyzed with the FACS analyzer. The severity of allergy and airway hyperreactivity can be evaluated by allergen–specific IgE and airway hyperresponsiveness to methacholine. In this study we evaluated the cell numbers with respiratory burst activity on activated eosinophils and correlated these cell numbers with the allergen–specific IgE and airway hyperresponsiveness to methacholine. Results showed that the cell number with respiratory burst activity of activated eosinophils was increased in those patients with more hyperresponsiveness to methacholine and correlated with PD20 of methacholine with r = –0.643 and p = 0.01. The number of activated eosinophils was also correlated with allergen–specific IgE with r = 0.641 and p = 0.025. There were increased cell numbers of activated eosinophils (EG2+/PMN) and cells with respiratory burst activity (DCF+EG2+/PMN) in the unstable asthmatic patients when compared to those of stable asthmatic patients. These results suggest that there is in vivo activation of eosinophils in the asthmatic patients, especially in the unstable patients and patients who have airways more hyperreponsive to methacholine. We concluded that the cell numbers with respiratory burst activity of activated eosinophils cannot only reflect the airway hyperresponsiveness but also the disease severity of asthmatic patients.