METHODS: Pediatric patients with suspected soybean allergy (n = 91) were enrolled, and symptomatic (n = 40) and asymptomatic (n = 51) cases were divided through oral food challenge (OFC) testing. Specific IgE (sIgE) antibodies to each recombinant allergen component were analyzed by enzyme-linked immunosorbent assay, and the diagnostic performances of the components were assessed by area under the receiver operating characteristic (ROC) curves (AUC).
RESULTS: Among the components listed in WHO/IUIS Allergen Nomenclature Subcommittee, Gly m 8 (2S albumin) showed the highest AUC (0.706). A combination of Gly m 8 and α' subunit of Gly m 5 (vicilin), improved the diagnostic performance of the single components. Moreover, the N-terminal extension region of α' subunit of Gly m 5, which has low cross-reactivity among the vicilins, showed higher diagnostic performance (AUC 0.695) than the full-length α' subunit of Gly m 5 (AUC 0.613). Based on these findings, we developed a fusion protein of Gly m 8 plus the extension region of α' subunit of Gly m 5; this fusion protein was very efficient for diagnosing soybean allergy (AUC 0.801).
CONCLUSIONS: sIgE antibody levels to the fusion protein of allergen components had a higher accuracy for diagnosing soybean allergy than any single allergen component.