How proteins aggregate can reduce allergenicity: Comparison of ovalbumins heated under opposite electrostatic conditions

Heated foods are recommended for avoiding sensitization to food proteins, but depending on thephysicochemical conditions during heating, more or less unfolded proteins aggregate differently. Whether the aggregationprocess could modulate allergenicity was investigated. Heating ovalbumin in opposite electrostatic conditions led to small (A-s,about 50 nm) and large (A-L, about 65 μm) aggregates that were used to sensitize mice. The symptoms upon oral challenge andrat basophil leukemia degranulation with native ovalbumin differed on the basis of which aggregates were used during thesensitization. Immunoglobulin-E (IgE) production was significantly lower with A-s than with A-L. Although two common linearIgE-epitopes were found, the aggregates bound and cross-linked IgE similarly or differently, depending on the sensitizingaggregate. The ovalbumin aggregates thus displayed a lower allergenic potential when formed under repulsive rather thannonrepulsive electrostatic conditions. This further demonstrates that food structure modulates the immune response during thesensitization phase with some effects on the elicitation phase of an allergic reaction and argues for the need to characterize theaggregation state of allergen