Enzyme‐Linked Immunosorbent Assay and Immunoblotting Determination of Antibody Response to Major Component Proteins of Soybeans in Patients with Soy Protein Intolerance

To evaluate the role of food-specific antibody response to soy protein and its fractions in patients with soy protein intolerance, allergen-specific IgG and IgE to these proteins were measured by enzyme-linked immuno-sorbent assays (ELISAS) and immunoblotting. A crude soy extract and the 7S, 11S, and whey fractions were isolated from commercial defatted soy flakes. Of 23 patients who underwent standardized soy challenges, seven were positive. The ELISA results showed no statistically different responses between the challenge-positive and challenge-negative groups in IgG or IgE specific to either the crude soy extract or the 7S, 11S, and whey fractions (p > .3 for all variables). In comparing the soy-positive patients, the level of IgE specific for 7S and 11S was significantly different compared with whey; the level of IgE specific for crude soy extract and 7S was significantly different compared with whey. The immunoblots reveal that IgG and IgE are present in varying amounts to multiple fractions of the soy protein. The study does not provide evidence for a pathogenic role of serum food-specific antibodies in soy protein intolerance.