Twenty-four-hour time course of eosinophil granule proteins ECP and EPX during bronchial allergen challenges in serum of asthmatic children

To study in vivo monitoring variables for bronchial allergen challenges, we investigated the time course of the eosinophil granule proteins, eosinophil cationic protein (ECP) and eosinophil protein × (EPX) after allergen provocation in serum. Thirty-two asthmatic children sensitive to house-dust mites and six healthy young adult controls were challenged by bronchial allergen provocations with Dermatophagoides pteronyssinus and D. farinae. Blood samples were taken at regular intervals up to 24 h. Base-line concentrations of ECP ( P <0.004), EPX ( P <0.002), and eosinophils ( P <0.001) were found to be increased in asthmatic children, as compared with healthy controls. ECP and EPX concentrations showed a uniform pattern with two characteristic features: 1) a rapid increase for both mediators up to 30 min after provocation over base-line values ( P <0.0001 and P <0.001), followed by a rapid decrease nearly to base-line values in the next 30 min; and 2) a steady increase for ECP and EPX up to 10 h ( P <0.02 and P <0.01), and even higher levels at 24 h, after challenge ( P <0.002 and P <0.003). We conclude that although eosinophils are activated in asthmatic children after bronchial allergen challenge, ECP and EPX concentrations are not suitable monitoring variables. Base-line eosinophils seem to predict the occurrence of a late-phase asthmatic reaction after allergen provocation.