A case of white bean allergy.

White bean allergy is uncommon and rarely reported. Herein, we report a case of white bean allergy in a patient with Down syndrome. A 7-year-old girl with Down syndrome experienced allergic symptoms twice after eating white bean and visited our hospital for a food allergy investigation. An ImmunoCAP assay revealed a white bean-specific IgE (13.4 kUA/L) in the patient's serum. In addition, her skin prick test result was positive. Moreover, ingestion of 2 g of boiled white beans in an oral food challenge test induced intermittent cough, desaturation, generalized urticaria, abnormal sleep, and mild hypotension. Thus, we diagnosed the patient with white bean allergy. We performed western blotting and mass spectrometric analysis and detected the following allergens: Phytohemagglutinin, group 3 late embryogenesis abundant protein, lipoxygenase, and legumin. In addition, we detected several candidate allergenic proteins for the first time. White bean, runner bean, or azuki bean was considered the primary source of sensitization because although immunoblotting inhibition tests revealed that the abovementioned beans inhibited other legumes, soybean, which she tolerates, showed little inhibition of the other legumes. However, we could not confirm whether the patient could ingest legumes other than soybean or white bean because her family did not wish to continue with further testing. This is the first report of a case of systemic allergic reactions to white bean in a child with Down syndrome. Further studies are needed to identify white bean allergens and understand the relationship between Down syndrome and white bean allergy.

[ANTIGENICITY OF SOY PROTEIN IN SOY-BASED INFANT FORMULA BONLACT® i].

BACKGROUND: The purpose of this study was to compare the antigenicity of Bonlact® i (BL) with that of defatted soy protein (SP) and soy protein isolate (SPI), which is the original source of BL, using sera from patients with soybean allergy. METHODS: Proteins were extracted from SP, SPI, and BL using PBS. Proteins in each sample were analyzed for antigenicity using inhibition ELISA with SP-specific IgE (sIgE), SDS-PAGE, and immunoblotting. Sere from patients with soybean allergy confirmed by an oral food challenge (OFC) (n=6, OFC+ Pt), and from patients who were positive for soy-sIgE without symptoms ( n = 7, sIgE+ Pt) were used for these assays. The cross-antigenicity of SP and BL with cow's milk (CM) proteins was also analyzed in the sera from patients with CM allergy using inhibition ELISA. RESULTS: SDS-PAGE showed that the proteins in BL produced a smear-like band in the low-molecular-weight region compared with that in SP and SPI. Inhibition ELISA against SP-sIgE showed that BL had a significantly lower inhibition rate than that of SP in both OFC+ Pt and sIgE+ Pt. Immunoblotting analysis showed that the bands of BL were thinner than those of SP and SPI. Additionally, SP and BL showed no cross-antigenicity with CM proteins. CONCLUSION: The proteins in BL was partially digested, and its antigenicity was lower than that of SP and SPI.