Continuous apple consumption induces oral tolerance in birch-pollen-associated apple allergy

Allergy. 2012 Feb;67(2):280-5. doi: 10.1111/j.1398-9995.2011.02744.x. Epub 2011 Nov 10.


Background: Patients with birch pollen allergy (major allergen: Bet v 1) have often an associated oral allergy syndrome (OAS) to apple, which contains the cross-reactive allergen Mal d 1. As successful birch pollen immunotherapy does not consistently improve apple related OAS symptoms, we evaluated whether regular apple consumption has an effect on OAS and immune parameters of Mal d 1 or Bet v 1 allergy.

Methods: A total of 40 patients with a clear history of birch pollen rhinoconjunctivitis and associated OAS to apple were included in an open, randomized, controlled clinical trial: 27 patients consumed daily defined amount of apple (1-128 g), doubling the amount every two to three weeks, while 13 patients remained untreated. Primary endpoint was the proportion of patients that achieved tolerance to at least 128 g of apple at the end of the study after 8 months. Exploratory endpoints were questionnaire about cross-reactive food and pollen allergy symptoms, conjunctival provocation test with birch pollen and Bet v 1, and in vitro tests (tIgE, sIgE, and IgG4 to Mal d 1 and Bet v 1; basophil activation test with both allergens).

Results: Seventeen of 27 patients in active group and none of 13 patients in control group (P = 0.0001) could tolerate a whole apple after the intervention. However, differences in endpoints reflecting systemic immune reactivity did not reach statistical significance.

Conclusion: In patients with OAS to apple, tolerance can be safely induced with slowly, gradually increasing consumption of apple. However, the observation of a relapse after discounting of apple consumption and absence of immunologic changes suggest that induced tolerance is only transient.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Allergens / immunology*
  • Betula / immunology*
  • Cross Reactions / immunology
  • Desensitization, Immunologic / adverse effects
  • Female
  • Food Hypersensitivity / complications
  • Food Hypersensitivity / immunology*
  • Food Hypersensitivity / therapy
  • Humans
  • Immune Tolerance / immunology*
  • Immunoglobulin E / immunology
  • Immunoglobulin G / immunology
  • Male
  • Malus / adverse effects*
  • Middle Aged
  • Pollen / immunology*
  • Rhinitis, Allergic, Seasonal / complications
  • Rhinitis, Allergic, Seasonal / immunology*
  • Rhinitis, Allergic, Seasonal / therapy
  • Young Adult


  • Allergens
  • Immunoglobulin G
  • Immunoglobulin E