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

SUMMARY

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 allergen-specific IgE assays and offering a safer and more specific alternative to oral food challenges.

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