Background No biological test can predict with certainty the persistence or resolution of IgE-mediated cow’s milk allergy. The purpose of this investigation was to evaluate the benefit of the basophil activation test (BAT) in predicting a child’s reaction to the oral milk challenge and to compare it with the specific IgE result using the most common thresholds (0.8 and 5 kUI/l).
Methods IgE-mediated allergic children admitted for a cow’s milk provocation test were included. Allergen-induced basophil activation was detected as a CD63-upregulation.
Results In our cohort of 56 children (average age 3.7 years), 17 (31%) reacted to the oral challenge. The BAT was interpretable for 52 children (93%) and was positive for every reactive child. The BAT had an accuracy of 96%, a sensitivity of 100%, a specificity of 97%, a positive predictive value of 94%, a negative predictive value of 100% and a correlation factor with the oral challenge φ of 0.957. The BAT area under the receiver operator characteristic curve (AUC) was 0.941. These scores were all higher than those obtained with the specific IgE values, whichever IgE positivity threshold was chosen (IgE AUC of 0.734). Furthermore, among the persistently allergic children, the severity of the clinical reaction was significantly correlated with the degree of basophil activation (p<0.001).
Conclusion The BAT could be a very valuable tool in the management of cow’s milk allergy by contributing to determining whether an oral challenge can safely be undertaken. The BAT could thereby help to avoid the danger, stress and expense of repeated positive challenges.