Diagnostic challenges in soy allergies: utility of the basophil activation test to distinguish allergy from sensitization to Gly m 4

Background.Soy allergy represents a diagnostic challenge, particularly when mediated by Gly m 4, a PR-10 protein known for its cross-reactivity with birch pollen allergens.Traditional diagnostic methods, including skin prick tests (SPTs) and specific IgE assays, often lack sensitivity or specificity, especially for Gly m 4-mediated allergies.Methods.In this study, the basophil activation test (BAT) was evaluated as a tool to distinguish true allergy from mere sensitization to Gly m 4. Results.A total of four patients sensitized to Gly m 4 and Bet v 1 (PR-10 of soy and birch) were included in this study.Two patients were confirmed allergic to soy based on positive BAT results with Gly m 4 and soy total extract, correlating with clinical symptoms of allergy.Conversely, two other patients were determined to be sensitized but clinically tolerant, as BAT results were negative, consistent with their symptom-free status during oral food challenges.Conclusions.The study highlights the limitations of traditional diagnostic methods, which often yielded false-negative or inconclusive results, and underscores the BAT's ability to provide functional evidence of allergen reactivity.We demonstrate the utility of BAT in identifying clinically relevant Gly m 4-mediated soy allergies.By enabling precise differentiation between allergy and sensitization, the BAT emerges as a valuable diagnostic tool, complementing molecular allergenspecific IgE assays and offering a safer and more specific alternative to oral food challenges Key words BAT; soy total extract; molecular allergen; tolerant; allergic; cross-sensitization; anaphylactic reaction; PR-10. Impact statementThe basophil activation test reliably distinguishes true soy allergy from Gly m 4 sensitization, offering a functional, non-invasive alternative to oral food challenges in complex diagnostic cases.