[Food allergy. I. Pathogenesis, clinicaL aspects and diagnosis].

Gut associated lymphoid tissue (GALT) and mucosa associated lymphoid tissue (MALT) form the pathophysiological basis for immune function of the gastrointestinal tract. The precondition for an immune response to food antigens is absorption through the mucosa. "M"-cells in the epithelial layer in Peyer's patches are specialized for antigen uptake. Foodstuff allergens either ingested or inhaled may cause, locally or systematically, a multitude of symptoms. All four allergic reaction mechanisms, according to the classification of Coombs and Gell, may occur alone or in combination. Due to the lack or reliable test procedures, allergic reactions to food often remain unrecognized or, on the other hand, are too often supposed. It is important to arrive at a clear definition of food allergies. Other causes of incompatibility to foodstuffs must be excluded, such as toxic effects, intolerance reactions to pharmacologically vasoactive or psychoactive substances in certain foods, and pseudo-allergic reactions and enzymopathies. Food allergies with type I reactions are easily recognized by means of a careful history and allergological examination, especially using scratch or prick tests with fresh food, RAST, and a carefully conducted elimination diet. None of the other available in-vitro test methods can replace the allergological examination. Some cases of food allergy are presented which demonstrate the often painful process from symptom to specific diagnosis.