The role of assay for allergen specific immunoglobulin G in the diagnosis of food allergy and intolerance

Adverse post-food reactions can manifest themselves both within a few minutes after contact with harmful food, as well as several or several dozen hours after eating potentially allergenic food protein. They can also cover a very wide spectrum of clinical symptoms, both mild or restricted, as well as very severe systemic reactions. Contemporary diagnosis of food allergy is primarily based on an interview and a thorough physical examination, which can be supplemented with additional tests carried out in vivo or in vitro. Both commonly used skin prick tests and laboratory tests involving the determination of class E mmunoglobulin concentrations specific for food allergens are helpful in the diagnosis of immediate IgE-dependent reactions. The observed spectrum of clinical symptoms suggests that not all unwanted post-food reactions occur in the type I hypersensitivity mechanism. Thus, tests for the assessment of specific IgE levels in the blood as well as those based on IgE-mediated reactions are insufficient to diagnose hypersensitivity reactions occurring according to other mechanisms. There are currently no reliable tests, either in vivo or in vitro, which could support the diagnosis of IgE-independent food hypersensitivity reactions. Also, there is no reliable evidence that measuring IgG specific for food allergens could be useful in diagnosing food allergies or intolerances, or that the presence of these antibodies causes any adverse effects. In the absence of clinical relevance of these tests, both European and global scientific allergological and immunological societies advise against the use of IgG tests in the diagnosis of allergies and food intolerance.