Relative Immunogenicity of Commonly Allergenic Foods versus Rarely Allergenic and Nonallergenic Foods in Mice

Abstract

Food allergies affect 6 to 8% of children and 2% of adults in the United States. For reasons that are not clear, eight types of food account for a vast majority (~90%) of food-induced hypersensitivity reactions. In this study, C57Bl/6 mice were used to test the hypothesis that commonly allergenic foods are intrinsically more immunogenic than rarely allergenic or nonallergenic foods in allergy-susceptible hosts. Groups of mice (n = 4 to 5) were injected intraperitoneally with the protein extracts (plus alum as an adjuvant) from chicken eggs, peanuts, almonds, filberts-hazelnuts, walnuts, soybeans, and wheat (commonly allergenic foods) and coffee, sweet potatoes, carrots, white potatoes, cherries, lettuce, and spinach (rarely allergenic and non-allergenic foods). Primary and secondary immune responses (as measured by specific IgG1 antibody serum levels) were measured by an enzyme-linked immunosorbent assay. Proteins from peanuts, almonds, filberts, sweet potatoes, cherries, and spinach elicited robust primary and/or secondary immune responses. Proteins from eggs, walnuts, and lettuce elicited poor primary responses but significant secondary responses. In contrast, wheat, soybeans, coffee, carrots, and white potatoes elicited barely detectable to poor primary and secondary immune responses. The order of the immunogenicity levels of these foods in mice is as follows: almonds = filberts > spinach (Rubisco) > peanuts ≥ sweet potatoes > cherries > lettuce > walnuts > chicken eggs > carrots ≥ white potatoes > wheat = coffee = soybeans. In summary, these data demonstrate for the first time that: (i) foods vary widely with regard to their relative immunogenicity in allergy-susceptible hosts and (ii) intrinsic immunogenicity in mice does not distinguish commonly allergenic foods from rarely allergenic or nonallergenic foods.