General Medical Information

Areas of Controversy and Continuing Investigation

Richard L. Mabry

Food Hypersensitivity
Little disagreement exists that IgE-mediated acute allergic reactions to food occur, such as hives after eating shrimp. Such acute hypersensitivity is suggested in the history and confirmed with in vitro specific IgE assay. Skin tests for this type of allergy present a danger of anaphylaxis. Controversy exists regarding delayed or cyclic food allergy (which involves mechanisms other than a Gell and Coombs type I reaction) in which continued ingestion of the offending food partially masks symptoms. Cyclic food allergy is best diagnosed with a careful analysis of dietary habits and symptom production followed by a challenge refeeding test in which omission of the suspected food from the diet for 4 to 7 days relieves symptoms and in which reintroduction causes symptoms to recur. The diagnosis is further confirmed by means of skin responses to intradermal testing, but the importance of symptom provocation by skin testing is questionable.

Enzyme-potentiated Desensitization
In enzyme-potentiated desensitization the enzyme b-glucuronidase is used to potentiate the action of small quantities of antigen. Unlike conventional immunotherapy, which depends on testing to identify specific offenders, enzyme-potentiated desensitization entails a mixture of antigens empirically chosen from inhalants, foods, and chemicals. Strict control of diet and antigen exposure during the initial period of therapy is combined with injections over a few weeks or months. Although investigations have been conducted in the United States for several years, no results have been published to substantiate the benefit of this method.