Heat treatment of egg white controls allergic symptoms and induces oral tolerance to ovalbumin in a murine model of food allergy

Scope: Heated foods often present low allergenicity, and have recently been used in specific oral immunotherapy for food allergies. However, the influence of heating on tolerogenicity of food allergens is not well elucidated. Here, we investigated biochemical, allergenic, and tolerogenic properties of heated egg white (EW) using a murine model of food allergy. Methods and results: Raw EWs were treated at 80 degrees C for 15 min (80EW, mild heating condition), 100 degrees C for 5 min (100EW, cooking condition), or 121 degrees C for 40 min (121EW, retort pouch condition), and freeze-dried. A transgenic OVA23-3 mice model expressing T-cell receptor specific for ovalbumin (OVA, a major EW allergen) induced Th2 cells and IgE production, and presented intestinal inflammation when fed untreated EW diet. 80EW-fedmice presented only moderate inflammation but high Th2 responses. 100EW-fedmice did not present inflammation but induced tolerance as seen in reduced T-cell responses and IgE levels. 100EW demonstrated higher digestive stability and slower absorption in intestine, compared with untreated EW and 80EW. 121EW was strongly aggregated, was not absorbed well, and developed Th1 responses without tolerance induction. Conclusion: OVA in EW treated only under a particular heat condition (e.g. 100 degrees C for 5 min) lost allergenicity, but possessed tolerogenicity.