Chapter 109 : Tests for Immunological Reactions to Foods

Abstract:

Food allergy is defined as an adverse immunological response to food. Some of the tests discussed in this chapter not only aid in the diagnosis of food allergies, but also are useful in monitoring the natural history of patients' food allergies over time, from diagnosis to oral tolerance. Once food allergy has been identified as the likely cause of symptoms, confirmation of the diagnosis and identification of the implicated food(s) can begin. There are a number of tools that aid in the diagnosis of food allergy, some of which are more commonly used, and they vary in their ability to provide an accurate diagnosis. Available studies include in vivo tests such as skin prick and intradermal testing, oral food challenges (OFCs), elimination diets, and patch testing and in vitro tests such as quantification of food-specific IgE and basophil histamine release (BHR). Tests that have not proven helpful in food allergy diagnosis include quantification of food-specific IgG, total serum IgE levels, BHR, and serum tryptase concentrations. Tests that need further study but show some promise include the atopy patch tests (APT), which may aid in the diagnosis of non-IgE-mediated disorders and delayed reactions to foods. Finally, important features of the studies mentioned in this chapter for the described tests that need to be appreciated by clinicians are (i) that the data generated may be particular to the study population and test material and (ii) that the age and clinical disease of the patients are important variables.