Food allergy in children--part I: pathogenesis and diagnostic approach

Abstract

Food allergy is a form of adverse food reaction to different nutritive agents caused by immunological mechanisms. This condition is frequent in individuals with genetic predisposition. Frequency of food allergies in childhood varies in general population from 0.3-7.5%. Characteristics of neonatal and infant gastrointestinal tracts are described, as well as the role of gastrointestinal tract's immunological immaturity in development of food sensitivity. Features of physical and immunological barriers of gastrointestinal tract are described as well as their role in physiological conditions, in digestion and absorption of foreign proteins and prevention of foreign agents penetration and potentially dangerous proteins into the systemic circulation. Gastrointestinal-associated lymphoid tissue (GALT) is the basic part of immunological barrier. Its first role is to induce oral tolerance. In normal conditions cytokins induce T cells towards Th2 response and also promote synthesis of IgA antibodies. Pathogenic mechanisms in evolution of reaginic hypersensibility in cases of chronic inflammation are also described. Pathological status of gama/delta T cells plays an important role in this process, resulting in loss of oral tolerance and development of sensibilitivity. Diagnostic procedures are multiple and complex. They consist of detailed history taking, clinical findings, in vitro and in vivo tests, endoscopy, elimination diets and oral provocation tests. Food allergy in childhood is often transient and resolves spontaneously.