chapter  13
26 Pages

Determination of Food Allergens and Genetically Modi‘ed Components

A food allergen is any component of food that induces an adverse immunologic response when ingested by a sensitized individual. The immune mechanisms involved are classi‘ed as IgE-mediated or non-IgE-mediated and can result in a wide range of cutaneous, respiratory, gastrointestinal, or cardiovascular symptoms.1 The

13.1 Introduction to Food Allergens ..................................................................... 349 13.1.1 Limits of Detection ........................................................................... 352

13.2 Detection of Allergenic Components of Food .............................................. 352 13.2.1 Immunochemical Methods for the Detection of Allergenic Foods .. 353

13.2.1.1 Enzyme-Linked Immunosorbent Assay ............................ 355 13.2.1.2 Dipstick and Lateral Flow .................................................. 358 13.2.1.3 Biosensors .......................................................................... 359

13.2.2 DNA-Based Methods ........................................................................ 359 13.2.2.1 Polymerase Chain Reaction ............................................... 359 13.2.2.2 PCR-ELISA ....................................................................... 362

13.2.3 New Technologies ............................................................................. 362 13.3 Genetically Modi‘ed Foods ......................................................................... 362

13.3.1 Detection of Components of Genetically Modi‘ed Foods ............... 363 13.3.2 The Starlink™ Corn Experience ...................................................... 363

13.3.2.1 Immunochemical Methods for Determination of Cry9C .....364 13.3.2.2 PCR Methods for Detection of Cry9C............................... 365 13.3.2.3 Post-Market Cry9C Exposure Assessment ........................ 367

References .............................................................................................................. 369

majority of immediate allergic responses to foods are related to food proteins that are absorbed undigested through the intestinal epithelium, where they bind to speci‘c IgE and trigger the release of mediators from intestinal mucosal and submucosal mast cells.2 A proportion of food allergens may become disseminated by gaining access to mucosal vasculature, resulting in generalized symptoms such as urticaria or anaphylaxis. Food allergies are more common in the ‘rst few years of life, probably due to immaturity of the intestinal barrier and the mucosal immune system. Although accurate epidemiological surveys are lacking, it is estimated that food allergies affect approximately 6% of children under 3 years of age and about 2% of adults in the United States.3,4 However, the prevalence of allergic reactions to speci‘c foods varies geographically and may depend on the frequency of consumption, the age of introduction into the diet, and the genetic makeup of the sensitized population. There has been an apparent increase in the incidence of certain food allergies over that in the past decade, but only a few of these reports are well documented.5-7 The common misidenti‘cation of other food intolerances as allergic reactions may explain some of these observations.