Immunoglobulin E-mediated hypersensitivity in food-producing animals.

Type I hypersensitivity has been described as a cause of allergic reactivity to inhalants, injectables, endoparasites, and ectoparasites in food animal species. In addition, IgE is credited with showing some host-sparing effect when produced in response to certain gastrointestinal and other parasites. Recently, the sophistication of diagnostic procedures has increased with the elucidation of epsilon heavy chain sequences, expressed protein, development of chimeric IgE antibodies, and production of species-specific anti-IgE reagents. Application of ELISA and Western blotting has replaced the passive cutaneous anaphylaxis test for demonstration of antigen-specific IgE in serum. Regulation of the IgE response is complex, and its dependence on induction of T helper cell type 2 cytokines is now established. The next frontier in IgE research, as for many inherited diseases, lies in understanding the genetic make-up of the animal and which genes are important in controlling the IgE response.