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Food Allergy

Foods are an important cause of allergic reactions including fatal anaphylaxis. Severe reactions to foods can occur at all ages, from infants receiving cow's milk or casein or whey hydrolysate formulas to children, adolescents, and adults. Although some reactions caused by formula proteins in infants may decrease in intensity with age, the risk for severe reactions to other foods persists for long periods of time, even in absence of exposure. Severe reactions have been associated with fish, shellfish, nuts and seeds, legumes, celery, and to a lesser extent with grains, milk, and eggs.

IMMUNOTHERAPY

Immunotherapy of IgE-mediated diseases has a high incidence of untoward reactions; therefore, alternative methods are being developed to reduce the risk-to-benefit ratio in the treatment of allergic disease. Although these methods are being developed primarily for use in the treatment of inhalant allergies, some

Pharmacologic therapies for the treatment of respiratory allergic disease have markedly improved in the last decade, but treatment for food allergy remains strict avoidance and symptomatic relief of systemic reactions with antihistamines, vasoconstrictors, and volume expanders. Novel immunotherapy methods that are currently being developed and studied for IgE-mediated disease suggest promise for effective and safe future therapies. The methods currently being tested include oral, immune complex, and peptide immunotherapy, as well as anti-IgE therapy and DNA vaccine therapy.

TABLE 1 -- EMERGING IMMUNOTHERAPY METHODS
Therapy Route Mechanism Safety
Oral immunotherapy Oral Tolerance Appears safe
Immune complex therapy Intradermal Unknown Appears safe
Peptide immunotherapy Subcutaneous/oral Diminish T-cell reactivity Appears safe
Anti-IgE Intravenous/subcutaneous Deplete allergen-specific IgE Appears safe
DNA immunization Subcutaneous Switch Th2 to Th1 response Unknown
 

Oral Immunotherapy

Oral immunotherapy with large doses of allergen has been shown to induce immunologic tolerance in animal models,  but studies in humans have shown mixed results in efficacy. These studies have been performed in patients with respiratory allergy associated with pollens. Taudorf et al demonstrate a beneficial clinical effect of oral immunotherapy in birch pollen-allergic patients during birch pollinosis. Eye symptom scores and conjunctival sensitivity by conjunctival provocation.

Immune Complex Therapy

Immune complex therapy using autologous immune complexes has also been investigated. Machiels et al studied the effects of antigen-antibody complex therapy for the treatment of immediate-type hypersensitivity disease. Patients suffering from allergic rhinitis and asthma associated with exposure to grass pollen were injected intradermally with antigen-antibody complexes prepared from grass pollen allergens and autologous-specific antibodies isolated from the sera of grass pollen-allergic patients. This form of therapy improves nasal and bronchial asthma symptom scores, and clinical benefit is achieved within weeks of treatment. In addition, this treatment prevents the expected seasonal rise in specific IgE antibodies without increasing specific IgG antibodies.

Peptide Immunotherapy

Peptide immunotherapy employs subcutaneous injection therapy with peptide fragments containing the allergenic epitope, rather than the complete protein, making the cross-linking of IgE molecules on the surface of mast cells and basophils unlikely. This form of immunotherapy would theoretically minimize the possibility of

The above novel approaches to the treatment of allergic disease have been allergen-specific, making treatment of multiple allergies potentially complicated. In allergic disease, a less specific form of therapy that could dampen or eliminate the allergic hypersensitivity state would be more desirable. Casale et al studied the

DNA Immunization

DNA immunization is another novel approach under study for the treatment of allergic disease. It was recently shown that naked plasmid DNA (pDNA) encoding an antigen is taken up in vivo by antigen-presenting cells; it is suggested that an endogenously produced protein or peptide fragment is then presented on the 

Novel approaches to therapy for allergic diseases are only in their infancy; more detailed investigations are required to better define the risk of adverse reactions, the duration of treatment effects, and the doses that will be tolerated or required for an appropriate long-lasting immunologic response. Peptide immunotherapy,

Peptide immunotherapy, anti-IgE therapy, and DNA vaccines have been studied using subcutaneous injection, like traditional immunotherapy. Immune complex therapy has been administered intradermally. The oral route of allergen therapy had been largely unsuccessful until recently. The reason is believed to be related to

MUCOSAL VACCINES

In the absence of clearly defined molecular and cellular mechanisms that mediate allergic reactions in the gut, it is difficult to speculate as to the most effective immunotherapeutic interventions. There are several possible therapeutic interventions that might prove successful for treatment of food allergies. First, it may be possible to preferentially increase the amount of secretory IgA and systemic specific IgG against a particular allergen using certain oral immunization regimens.