Relationship between activated eosinophils of the bronchial mucosa and serum eosinophil cationic protein in atopic asthma.

We biopsied the bronchial mucosa of 20 atopic bronchial asthma patients and measured their serum eosinophil cationic protein (ECP) levels as a means of assessing whether serum ECP could be as a marker of airway eosinophil inflammation. We also investigated the relationship between serum ECP levels and airway hypersensitivity, pulmonary function, peak expiratory flow (PEF) and attack scores. EG2 monoclonal antibody was used to immunostain bronchial mucosal tissue, and positive cells were expressed as the number of positive cells per square millimeter of lamina propria mucosae. A significant correlation was found between bronchial mucosa EG2+ cell counts and serum ECP levels (r = 0.66, p < 0.01), but no clear relationships were detected between serum ECP levels and airway hypersensitivity, pulmonary function, PEF or attack scores. Based on the above findings, serum ECP levels reflect airway eosinophilic inflammation, but ECP levels must be considered in combination with other parameters in relation to the pathophysiology of asthma.