HEAT DENATURATION OF EGG-WHITE PROTEINS ABROGATES THE INDUCTION OF ORAL TOLERANCE OF SPECIFIC TH2 IMMUNE-RESPONSES IN MICE

Human foods are usually prepared by cooking. Boiling of chicken egg-wh ite (EW) led to decreased allergenicity, and abrogated intestinal upta ke of immunoreactive ovalbumin (OVA) when fed to mice. Therefore, the effects of oral administration of boiled EW were examined further in B ALB/c mice. Specific IgE, IgG(1) and IgG antibody responses were suppr essed by raw EW, but not by EW boiled for 5 or 60 min, fed prior to se nsitization with 10 mu g OVA or 1 mu g DNP-OVA in alum. Similar result s were obtained when mice were sensitized with 10 mu g conalbumin, ovo mucoid or lysozyme in alum. BALB/c spleen cell proliferation and secre tion of Th2 cytokines IL-4 and IL-5 during in vitro stimulation with O VA were also suppressed by feeding raw EW, but not by boiled EW. Altho ugh heat denaturation of proteins can minimize allergenicity, the pres ent results suggest that over-cooking of proteins may affect their int estinal antigen processing and thus prevent the induction of oral tole rance.