Immunotherapy for food allergies. Past, present, future

Egg oral immunotherapy in nonanaphylactic children with egg allergy

BACKGROUND

There is no current active treatment for food allergy. Traditional injection immunotherapy has been proved unsafe, and thus there is a need for other forms of immunotherapy.

OBJECTIVE

The purpose was to study the safety and immunologic effects of egg oral immunotherapy (OIT). The short-term goal was to desensitize subjects to protect against accidental ingestion reactions. The eventual goal was to induce lasting clinical and immunologic tolerance.

METHODS

Subjects with a history of egg allergy but without a history of anaphylaxis to egg underwent a 24-month egg OIT protocol involving modified rush, build-up, and maintenance phases. Double-blind, placebo-controlled food challenges were performed at study conclusion. Egg-specific IgE and IgG concentrations were followed.

RESULTS

Seven subjects completed the protocol. Egg-specific IgG concentrations increased significantly, whereas egg-specific IgE concentrations did not significantly change. Three subjects tolerated known or possible accidental egg ingestions while receiving OIT. During double-blind, placebo-controlled food challenges at study conclusion, all tolerated significantly more egg protein than at study onset and than that found in the typical accidental exposure. Two subjects demonstrated oral tolerance.

CONCLUSION

This study provides proof of concept that OIT can be safely used for patients with egg allergy without a history of anaphylaxis to egg. Egg OIT does not heighten sensitivity to egg and might protect against reaction on accidental ingestion. Whether OIT will induce clinical oral tolerance cannot be concluded from this initial cohort.

CLINICAL IMPLICATIONS

Use of allergen-specific OIT to protect subjects with food allergy from reaction on accidental ingestion would represent a significant paradigm change in the treatment of food allergy.

Seafood allergy

PURPOSE OF REVIEW

Given the importance and prevalence of seafood in our economy and diet, interest in the adverse effects of seafood-induced allergic reactions has increased both in the lay population and the scientific arena. The purpose for this review article is to provide an overview and discussion of current seafood-allergy research.

RECENT FINDINGS

Current research has produced the discovery of new seafood allergens as well as a better understanding of the interactions of allergens with the host, and the relationships of IgE antibodies with specific allergens. Crossreactivity of similar molecules from seafood and nonseafood sources provides a better understanding of an allergen's role in seafood allergy and a basis to improve patient identification and treatment.

SUMMARY

Findings in recent literature show potential for more precise diagnosis and safer, more effective treatment of seafood allergies.

IgE-mediated food allergy--extensive review of the literature

Adverse reactions to food, i.e. food allergy and intolerance have gained considerable attention. This overview focuses on the diagnosis and management of IgE-mediated food allergy that is believed to be responsible for most immediate-type food-induced hypersensitivity reactions. Clinically, these reactions are characterised by a variety of signs and symptoms that occur within minutes or hours after consumption of the offending food. Reactions may be limited or more generalised with involvement of the skin, nose, eyes, and/or lungs. In more severe cases, cardiovascular symptoms including hypotension, shock, cardiac dysrhythmias and death can occur. In food-allergic individuals, IgE is produced against naturally occurring food components, primarily glycoproteins that usually retain their allergenicity after heating and/or proteolysis. While adults tend to be allergic to fish, crustaceans, peanuts and tree nuts, children tend to be allergic to cow's milk, egg white, wheat and soy more frequently. "Emerging" food allergens include tropical fruits, sesame seeds, psyllium, spices and condiments. These allergies frequently represent a cross-allergy to an allergen derived from another source, e.g. pollens or natural rubber latex. The evaluation of IgE-mediated food allergy relies on a careful history, physical examination, appropriate skin testing or in vitro testing with food extracts, and/or double blind, placebo-controlled food challenges. Avoidance remains the mainstay of therapy. However, allergens may be "hidden" and labelling can be non-precise or misleading, thereby severely hampering prevention. Patients with severe allergies should keep at hand an emergency kit with adrenaline, an antihistamine and an injectable rapid onset-of-action corticosteroid. At present there is no evidence to support the use of immunotherapy, except for research purposes. Production of "hypoallergenic" food is hampered by incomplete methods for assessing the allergenic potential of such novel foods.