Correlations between basophil activation, allergen-specific IgE with outcome and severity of oral food challenges

Background Double-blinded, placebo-controlled food challenges (DBPCFCs) remain the gold standard for diagnosing food allergies. Skin prick tests (SPTs) and allergen-specific IgE (sIgE) are routinely used in medical practice but are not sufficient to predict severity of clinical reactivity. Objective To compare the utility of SPT wheal diameter, sIgE, allergen-specific IgG4 (sIgG4), total IgE (tIgE), sIgE/sIgG4 and sIgE/tIgE ratios, peanut component-specific IgE, and basophil activation in predicting outcome and severity of reactions at DBPCFCs. Methods Sixty-seven subjects (12-45 years old) underwent DBPCFCs for peanut, tree nut, fish, shrimp, and/or sesame as part of screening for enrollment in a clinical trial. The SPT, sIgE, tIgE, sIgG4, and peanut component-specific IgE (if applicable) levels were measured. CD63 upregulation on basophils in response to in vitro allergen challenge was analyzed by flow cytometry. Correlations between these measurements and DBPCFC severity scores were analyzed. Results The SPT and sIgE showed a weak correlation with DBPCFC severity scores, but tIgE and sIgG4 did not. The sIgE/sIgG4 ratio differentiated between positive and negative reactions but did not correlate with DBPCFC severity scores. A low positive correlation was seen between DBPCFC severity score and Ara h 2 IgE, whereas a low negative correlation with Ara h 8 IgE was observed. Basophil activation was positively correlated with DBPCFC severity scores. Receiver operating characteristic curves showed basophil reactivity had the largest area under the curve at 0.904 and sIgE at 0.870. Conclusion These results indicate that basophil activation testing can enhance discrimination between allergic and nonallergic individuals and could serve as an additional tool to predict clinical severity.