Mechanisms of food allergy

A new educational review published in the journal Pediatric Allergy and Immunology, through discussion of three cases of childhood food allergy, covers the subjects of typical IgE-mediated food allergy, eosinophilic proctocolitis and tolerance acquisition.

It is now well recognised that an immune response to food must be preceded by an initial encounter with an antigen. In childhood this initial sensitization results from initial antigen recognition in the gut mucosa or through cutaneous exposure. The mucus at the inner surface of gut epithelial cells plays a major role as a barrier to potential foreign antigens. However, this protection is reduced in the first weeks of life. Indeed, reduced gastric acidity in young infants, and frequent prescription of proton pump inhibitors for gastric reflux conditions in newborns, are suspected factors that enhance allergic sensitization to foods. As the gastrointestinal surface barrier naturally improves with age, so the incidence of food allergy tends to decrease with age.

This paper explores some of the many areas that are still poorly understood such as whether the mechanism of allergic sensitization influences the types of immune response, i.e. predominantly IgE type symptoms, or eosinophil-driven symptoms or gastrointestinal symptoms probably related to T-cell-driven inflammation. The educational review concludes with four multiple choice questions relating to food allergy sensitisation and tolerance acquisition.

Reference: Eigenmann PA. 2009 Pediatric Allergy and Immunology. Vol 20: pp. 5–11

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