Oral allergy syndrome (OAS) occurs in patients with a prior cross-reactive aeroallergen sensitization and clinically presents with oralpharyngeal symptoms after ingestion of a triggering fruit or vegetable. Although controversial, these symptoms may progress to systemic symptoms outside the gastrointestinal tract in 8.7% of patients and anaphylactic shock in 1.7%.
OAS's underlying pathophysiology may play a role in clinical presentation and outcome, depending on whether the cross-reactive protein is a heat-labile PR-10 protein, a partially labile profilin, or a relatively heat-stable lipid transfer protein. Profilin is an actin-binding protein involved in the restructuring of the actin cytoskeleton. It is found in all eukaryotic organisms in most cells.
Diagnostic testing is variable based on the underlying food tested, but fresh food skin prick test typically has the highest sensitivity.
Cross-reactivity in Pollen-Food Allergy Syndrome (PFAS) or Oral Allergy Syndrome (OAS) (click to enlarge the image).
Treatment centers on avoidance and the consideration of self-injectable epinephrine. Because of its relationship with a cross-reactive aeroallergen sensitization, subcutaneous immunotherapy and sublingual immunotherapy have also been therapeutically tried with mixed results.
Which allergen cross-reacts with Bet v1 (birch)?
(A) Ara h1 (peanut)
(B) Mal d 1 (apple)
(C) Ara h3 (peanut)
(D) Bos d (milk)
(E) Gal d (egg)
(F) Hev b2 (latex)
Answer: B, apple. Pollen sensitizations linked to food allergies was first reported with birch pollen and apples 50 years ago.
For patients:
Do raw or fresh fruits leave you sneezing, sniffling and with an itchy mouth, lips and throat? You may have oral allergy syndrome.
References:
Oral allergy syndrome: a clinical, diagnostic, and therapeutic challenge. Webber CM, England RW. Ann Allergy Asthma Immunol. 2010 Feb;104(2):101-8; quiz 109-10, 117.
Profilin may be a pan-allergen among plants that crossreacts between pollen, fruits, vegetables and latex http://goo.gl/ZUPRQ
Birch-Apple Syndrome Treated with Birch Pollen Immunotherapy (Oral Allergy Syndrome) http://goo.gl/4cASx
In birch-apple syndrome (oral allergy syndrome), eating apple does not affect the respiratory tract. Annals of Allergy, Asthma and Immunology, 2011.
In birch-apple syndrome (oral allergy syndrome), eating apple does not affect the respiratory tract. Annals of Allergy, Asthma and Immunology, 2011.
Image source: Head and neck. Wikipedia, public domain.
