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

Abstract

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. 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. 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. The proteins in BL was partially digested, and its antigenicity was lower than that of SP and SPI.