Heat Denaturation of Egg‐White Proteins Abrogates the Induction of Oral Tolerance of Specific Th2 Immune Responses in Mice

Abstract

Human foods are usually prepared by cooking. Boiling of chicken egg-white (EW) led to decreased allergenicity, and abrogated intestinal uptake of immunoreactive ovalbumin (OVA) when fed to mice. Therefore, the effects of oral administration of boiled EW were examined further in BALB/c mice. Specific IgE, IgG 1 and IgG antibody responses were suppressed by raw EW, but not by EW boiled for 5 or 60 min, fed prior to sensitization with 10 mg OVA or 1 mg DNP-OVA in alum. Similar results were obtained when mice were sensitized with 10 mg conalbumin, ovomucoid or lysozyme in alum. BALB/c spleen cell proliferation and secretion of Th2 cytokines IL-4 and IL-5 during in vitro stimulation with OVA were also suppressed by feeding raw EW, but not by boiled EW. Although heat denaturation of proteins can minimize allergenicity, the present results suggest that over-cooking of proteins may affect their intestinal antigen processing and thus prevent the induction of oral tolerance.

Food-Cooking Processes Modulate Allergenic Properties of Hen’s Egg White Proteins

“…Bu et al [14 ]indicated that fermentation with lactic acid bacteria could significantly reduce the antigenicity of α-LA and β-LG in skim milk; combined strains of Lactobacillus helveticus and Streptococcus thermophilus were even more effective. The influence of heat treatment and enzymatic digestion on the allergenicity of purified egg proteins either alone or in combination has been described by other investigators [12]. Our data reveal that Chinese traditional cooking approaches can also reduce the allergenicity of egg protein and thus represent a novel pathway to modulate the allergenicity of food allergens.…”

“…Unfortunately, most of the endeavors were unsuccessful [12]. It was reported that protein from processed egg was significantly lower than that of raw egg [13].…”

In Vitro Determination of the Allergenic Potential of Egg White in Processed Meat

“…Despite these potential sources of protein interaction, only a few allergens do not survive processing. Heat treatment has been recognized as a way of reducing allergenicity and boiled hen's egg has been reported as less allergenic [2–5]. However, severe food hypersensitivity reactions are also described for heat treated hen's egg [6].…”

Assessment of Allergenic Activity of a Heat-Coagulated Ovalbumin afterin VivoDigestion

“…As indirect proof that heat-denatured proteins are not allergenic, Peng et al reported that heat-denaturation of egg white proteins abrogated the induction of oral tolerance of specific Th2 immune responses in mice. 13) On the other hand, Urisu et al reported that 37 of 38 subjects (97%) who immediately manifested positive reactions to freeze-dried egg white did not respond to heated egg white in double-blind, placebo-controlled tests. 14) It is unclear how heat-coagulated proteins digested in the gastrointestinal tract and hydrolyzed peptides, with or without allergenic activity, are absorbed into portal blood.…”