EOSINOPHIL ACTIVITY MARKERS IN PERIPHERAL-BLOOD HAVE HIGH PREDICTIVE VALUE FOR BRONCHIAL HYPERREACTIVITY IN PATIENTS WITH SUSPECTED MILD ASTHMA

The present study aimed to evaluate the predictive value of eosinophil s and markers of their activity for bronchial hyperreactivity (BHR) in a population of patients with recently developed clinical symptoms of asthma. The activation oi eosinophils was estimated by measuring eosi nophil cationic protein (ECP) in serum. In addition, flow cytometry tv as used To measure the expression of the EG2-epitope on intracellular ECP in eosinophils from peripheral blood. Twenty-eight consecutive pat ients with clinical history of asthma were studied, Of the 28 patients , 18 had a positive branchial challenge test measured as PD(20)less th an or equal to 1600 mu g histamine, A significantly higher concentrati on of eosinophils and a trend to higher ECP in the peripheral blood wa s found in the hyperreactive group than in the. nonreactive group, How ever, the intracellular expression of ECP did not correlate with the P D20 value, and no significant difference between the groups was found, With one eosinophil activity marker, either serum ECP or EG2, ERR cou ld be predicted in 70% of the patients. If we combined any two of the activity markers (serum ECP, EG2, or the percentage of eosinophils), t he predictive value increased to 100%, We conclude that the blood eosi nophil concentration, as well as, to some extent, serum ECP, has a hig h specificity for BHR in patients with recently developed clinical sym ptoms of asthma, Despite normal bronchial reactivity, some patients ha d signs of activated eosinophils, i,e., high serum ECP and increased E G2 expression. Thus, these markers may reflect early stages in the dev elopment of BHR. Our results also indicate that a combined evaluation of percentage of eosinophils and of eosinophil activity markers is of clinical value to predict BHR.