Higher serum eosinophil cationic protein levels in children with cow's milk allergy

Background: In the pathogenesis of cow's milk allergy, abnormal immunologic ally mediated reactions play a basic role. Eosinophil activation also parti cipates in the development of several allergies. The purpose of this study was to characterize the degree of this activation by measuring the serum le vel of eosinophil cationic protein (sECP) and establishing whether it is a useful parameter in monitoring oral cow's milk allergy. Methods: The sECP level of 35 patients with previously confirmed cow's milk allergy (mean age, 16 months) was evaluated using a fluoroimmunoassay befo re the cow's milk rechallenge test and at 2 hours and 24 hours after cow's milk challenge. Results: Of the 35 children with previously confirmed cow's milk allergy, 1 0 had positive clinical reactions after the milk rechallenge test, whereas 25 children had no reaction. The median sECP level of all the patients befo re the challenge test was significantly higher (12.4 mug/L) than that of th e control group (4.3 mug/L) (P < 0.05). Two hours after the challenge, the me dian sECP of all patients (9.4 mug/L) was lower than the starting values . The median sECP levels were higher in children with positive challenge te st results at all time points. However, this difference was not statistical ly significant. Conclusions: The normalization of sECP level may indicate the cessation of the cow's milk allergy. Therefore, the measurement of sECP may be helpful i n determining the optimal time in which to repeat the challenge test, when the result will more likely be negative. The significant decrease of the sE CP level 2 hours after the beginning of milk challenge test may be explaine d by the fact that this protein is excreted into the intestinal lumen.