THE ATOPIC DOG - A MODEL FOR FOOD ALLERGY

The renewed interest in food allergy and its investigation has been ha mpered by the lack of an appropriate animal model with similar compara tive aspects of form and function relative to humans. Therefore we hav e been characterizing an inbred colony of high immunoglobulin E-produc ing dogs that were immunized subcutaneously with food antigen extracts in alum and that developed clinical manifestations of food allergy af ter oral challenges with food antigen. These dogs had appreciably high IgE antibody titer to specific food antigens, as measured by an enzym e-labeled immunodot assay. Skin test results for the food antigens wer e consistently positive, as evidenced by a wheal-and-hare reaction. Ga stroscopic food sensitivity was tested through an endoscope by injecti ng allergenic food extracts into the gastric mucosa after intravenous injection of Evans blue dye. Mucosal changes included swelling and ery thema, some petechiae and blue patching, and in some instances general ized gastric erythema and hyperperistalsis. Examination of immediate-r eaction biopsy specimens revealed edema and few inflammatory cells. Ex amination of late reaction biopsy specimens revealed increased eosinop hil and mononuclear cell infiltrations typical of late-phase allergic inflammatory responses. Direct mucosal challenge with food extracts co nfirmed the clinical and immunologic evidence of food allergy in these immunized dogs and suggests the usefulness of the atopic dog as a mod el for food allergy. This model might also be useful in detecting hidd en food allergies in unexplained inflammatory gastrointestinal tract d iseases.