How do we know when peanut and tree nut allergies have resolved?

Peanut (PN) and tree nut (TN) allergies cause 50% of all deaths from food-related anaphylaxis

Over the last two decades, the prevalence of peanut and tree nut allergy has increased throughout the Western world. Adverse reactions to these foods account for over 50% of all deaths resulting from food-related anaphylaxis. Until recently, evidence suggested that all peanut and tree nut allergy were permanent. It is now known that about 20% and 10%, respectively, of young patients outgrow peanut and tree nut allergies.

Markers of tolerance

Achieving tolerance is associated with:

- increasing circulating T regulatory cells
- reduced production of allergen-specific IgE


Regulatory T cells - 6 groups have been described as of year 2010 (click to enlarge the image).

Clinical predictors of tolerance

However, reliable predictors of resolution are not yet available. Physicians try to make a correlation between skin test wheal size and allergen-specific IgE, at the time of diagnosis and likelihood of resolution.

Resolution of peanut or tree nut allergy cannot be determined conclusively by either allergen-specific IgE analysis or by skin prick testing.

Oral food challenge is the gold standard for determining resolution of food allergy. Food challenges should only be undertaken in a clinical setting fully equipped to deal with a potential severe adverse reaction.


8 top allergens account for 90 percent of food allergies. Specific IgE levels (sIgE) that predict the likelihood of passing an oral food challenge are shown in the figure. (click to enlarge the image).

8% of peanut (PN) allergy recurs after resolution

8% of patients who outgrow peanut allergy may suffer a recurrence, but recurrent tree nut allergy has not been reported to date.

Therapy is still only experimental

Induction of tolerance through oral immunotherapy (OIT) or sublingual immunotherapy (SLIT) is now studied, but remains experimental. Studies have reported short-term desensitization to peanut, but ongoing follow-up will determine if tolerance is achieved long term.

References:

How do we know when peanut and tree nut allergy have resolved, and how do we keep it resolved? Clinical & Experimental Allergy, 2010.

Basophil Activation Test (BAT) Helps Predict Safety of Oral Challenge in Milk Allergy http://goo.gl/nDAM

Peanut Allergy: An Evolving Clinical Challenge (review), 2011.

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