Allergic proctocolitis, food-induced enterocolitis: immune mechanisms, diagnosis and treatment.

The term food allergy refers to the immune reaction (mediated by IgE or otherwise) that develops in response to the ingestion of a concrete type of food. Among the different potential manifestations of an allergic reaction, those exclusively affecting the gastrointestinal system are described. In recent years, the study of non-IgE-mediated food allergy has grown in relevance. These disorders are almost always of a transient nature, inherent to (though not exclusive of) nursing infants, and with gastrointestinal symptoms that may have variable repercussions upon the nutritional state of the patient. The prevalence of such reactions is not known, though some studies report that up to 60 % of all cases of allergy to cow's milk proteins (CMPs) are due to non-IgE-mediated mechanisms. The latency period between the time of ingestion and the appearance of the first clinical manifestations is greater than in the case of IgE-mediated reactions, and the underlying immunopathological mechanism has not been clearly established although it is accepted that T cell mediation is involved. The gastrointestinal problems derived from these delayed or chronic reactions comprise allergic proctocolitis, enterocolitis and food protein enteropathies. These digestive disorders tend to appear in the first months of life, and are of a progressive and generally self-limiting nature, with resolution at about two years of age. The most commonly implicated food is milk and, in our setting, there have also been reports implicating fish, egg and rice although such reactions can be triggered by any protein introduced into the infant diet. These manifestations disappear after removing the causal protein from the diet. When the causal proteins are CMPs, a highly hydrolysed infant formula is supplied as substitute, and if the latter is not tolerated, an elemental amino acid-based formula is prescribed.