Development of oral immunotherapy model using B10.A mice and egg white lysozyme

Oral immunotherapy for food allergy has been the focus of a lot of attention recently. The patients have to eat allergenic food instead of eliminating it in this therapy and there is no established standard method yet. To promote clear understanding and improvement of oral immunotherapy, the present study using B10.A mice investigated the effect of multiple oral administration of a model antigen, egg-white lysozyme, on both the antibody response and the anaphylactic reaction induced by subsequent administration of lysozyme. Various doses of egg-white lysozyme (0-100 mg/mouse) were administered to mice intragastrically for 6 d; then additional lysozyme was administered via the intraperitoneal route in all groups. Lysozyme-specific antibody responses were promptly induced by the first oral administration and enhanced by intraperitoneal administration. An anaphylactic reaction was further induced in these sensitized mice by intragastric administration of lysozyme, and the symptoms of shock were compared in order to evaluate the effects of pretreatment. Interestingly, the decrease in rectal temperature which is one of the common anaphylactic symptoms in mice was suppressed in all of the oral pre-administration groups, and the effects were highest in the group that received 20 mg. Consequently, this study using B10.A mice has shown that sensitization can be induced by intragastric administration of lysozyme instead of oral tolerance; however, anaphylactic shock induced by subsequent intragastric administration of lysozyme is suppressed. This mouse model would be useful for assessing the method of oral immunotherapy.