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. Achieving tolerance is associated with increasing circulating T regulatory cells and reduced production of
allergen-specific
IgE. Reliable predictors of resolution are not yet available. A direct correlation between skin test weal size and
allergen-specific
IgE, at the time of diagnosis and likelihood of resolution, has been reported. 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. Approximately 8% of patients who outgrow
peanut allergy may suffer a recurrence, but recurrent
tree nut allergy has not been reported to date. Infrequent ingestion of peanut may be related to the re-emergence of
allergy. Induction of tolerance through oral
immunotherapy or sublingual immunotherapy is now being actively studied, but remains experimental. Studies have reported short-term desensitization to peanut, but ongoing follow-up will determine whether tolerance is achieved long term.