Immunological Basis of GI Food Allergy

My review of the article: The Immunological Basis for Gastrointestinal Food Allergy


Summary: Food Allergies are now being recognized as being a treatable component of the atopic march.

Food allergies are common in children. Significant impact on quality of life (more research is needed because of this increasing). Recently there has been a shift in the recommendations after realization that delayed food exposures may be harmful in immune sensitization. “Instead strategies aimed at early introduction of foods to induce oral tolerance are now being re-evaluated…very encouraging results are being obtained in desensitizing allergic children via oral tolerance.” (TH3 vs. Th1 responses). The goal is not to induce complete tolerance in all cases but to raise thresholds, thus minimizing reactions to trace proteins (increasing quality of life by better control of allergy).

Research has shown that all infants have T cell responses to food antigens . In a small subset of children, there is an inappropriate immune response which results to sensitization of food antigens. “The critical question is not necessarily exposure to food antigens but the nature and type of immune response which an individual generates to these antigens.”… not the type, timing or dose of exposure but these variables are imposed on the individual, and complex immune system- in a time when the immune system is still developing (infancy).

Progress in GI food allergy remains slow, given all the complexities. Food allergy in children remains treatable when properly diagnosed and after a period of avoidance, oral tolerance is developed. The studies have increasing emphasis on immunology.

The paper goes on to discuss current research on the timing (early exposures or delayed introductions of food proteins into the infants diet) is affecting the rise in food allergy. It sites this article article for references as an excellent read on the growing/ongoing subject of research into infant food allergy (delayed introductions past 4-6mo. May have negative effects vs. previously thought of protective effects on oral tolerance.

The article goes on to discuss Regulatory T Cells and Food Allergy. “it is clear that there exists a population of CD4+, CD25+ T cells in blood whose primary function is to regulate immune responses”. Studies have shown that infants who develop food allergies have lower Treg cells function than non-allergic infants…”suggesting that a defect in Tregs may predispose to food allergy”. More research is needed in this area.

It covers a little in this article on desensitization in food allergy- by repeated systemic treatment with allergen. It is being recognized as treatment for allergies although specific mechanisms remain unclear it is thought to be “induction of Treg cells or blocking anti-bodies, or both. Desensitization is sublingual immunotherapy (SLIT)- small amount of allergen is placed under the tongue, and oral immunotherapy (OIT) which is feeding small amounts of the allergen". It does go onto to describe a more recent approach of introducing allergens via extensively heated proteins (with IgE antibody allergy) and studies have confirmed this with milk allergic children tolerating extensively heated milk. It goes onto to clarify that the goal of this immunotherapy isn’t only to allow the food to be completely tolerated (non-allergenic) but to simply raise the threshold of tolerance in anaphylaxis response allergy (thereby increasing quality of life).

The article also sites the Finnesh Allergy Programme 2008-2018 as a “highly ambitious project to reduce the burden of allergies” Stating that the background is based on immunological responses- focused on continuous exposure to antigens and strengthening and restoring immune tolerance mechanisms.

The article wraps up with a mention of delayed onset food allergies (and how slow research is in understanding it), but points out that IgE allergy are T-cell dependant as well so that there can be crossovers in strategies.