An oral sensitization model in Brown Norway rats to screen for potential allergenicity of food proteins

We developed an oral sensitization protocol for food proteins for the rat. Young Brown Norway (BN) rats were exposed to 1 mg ovalbumin (OVA) by daily gavage dosing for 42 days without the use of an adjuvant. OVA-specific IgE and IgG responses were determined by ELISA. On an oral challenge with OVA s ome clinical symptoms of food allergy-like effects on the respiratory syste m, blood pressure, and permeability of the gastrointestinal barrier were st udied. In addition, BN rats were orally exposed to a total hen egg white pr otein (HEW) extract and cow's milk (CM) and the specificities of induced an tibody responses were compared with the specificities of antibodies in sera from egg- and milk-allergic patients using immunoblotting Animals orally e xposed to the allergens developed specific IgE and IgG antibodies which rec ognized the same proteins compared with antibodies from egg- or CM-allergic patients. Among the various clinical symptoms of food allergy, gut permeab ility was increased after an oral challenge. In addition, some animals demo nstrated a temporary decrease in breathing frequency or systolic blood pres sure. The results oh obtained show that the Brown Norway rat is a suitable animal model for inducing specific IgG and IgE responses on daily intragast ric dosing of OVA without the use of an adjuvant. Moreover, local immune-me diated effects on oral challenge are observed. The observation that enteral ly exposed BN rats and food-allergic patients demonstrate antibody response s to a comparable selection of proteins on exposure to different protein mi xtures (HEW and CM) further supports the suitability of the BN rat as an an imal model for food allergy research and for the study of the allergenicity of (novel) food proteins. (C) 1999 Academic Press.