2011 Nov 10. doi: 10.1111/j.1398-9995.2011.
Continuous apple consumption induces oral tolerance in birch-pollen-associated apple allergy.
Kopac P  , Rudin M , Gentinetta T et al

Division of Allergology, Department of Rheumatology, Clinical Immunology and Allergology, Inselspital, University of Bern ADR-AC GmbH, Bern, Switzerland University Clinic of Respiratory and Allergic Diseases, Golnik, Slovenia.

Abstract
To cite this article: Kopac P, Rudin M, Gentinetta T, Gerber R, Pichler C, Hausmann O, Schnyder B, Pichler WJ. Continuous apple consumption induces oral tolerance in birch-pollen-associated apple allergy. Allergy 2011; DOI: 10.1111/j.1398-9995.2011.02744.x. ABSTRACT: 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.