Hazelnut allergy. Validation of diagnostic procedures on the basis of double-blind placebo-controlled food challenges

Hazelnut is one of the most frequent causes of food allergy. The diagnosis is based on patient's history, detection of specific IgE (CAP) and positive skin prick test. However, the properly performed double-blind, placebo-con trolled food challenge (DBPCFC) is the only scientifically accepted test fo r the confirmation of food allergy. Other diagnostic methods can be validat ed only in patients, in whom allergy was confirmed by DBPCFC. So far, DBPCF C with hazelnut has never been performed. In this study, 23 patients with t he history of an allergy to hazelnut underwent DBPCFC. Furthermore, skin pr ick tests with different hazelnut and pollen extracts, determination of spe cific IgE to hazelnut, to pollen from hazel and birch, and to the main birc h allergens Bet v 1 and Bet v 2 were performed. Nineteen patients showed a positive DBPCFC. All of them complained about an oral allergy syndrome. In addition, one patient suffered from rhinoconjunctivitis with a delay of 4 h ours. All patients were sensitized to pollen from hazel and birch and to Be t v 1. Just 5 patients showed specific IgE to Bet v 2. The sensitivity of s kin prick test for hazelnut proved to be in these patients 84 - 95% (depend ing on the extract). The sensitivity for the determination of specific IgE (CAP) was 79%. In conclusion, skin prick test and CAP method proved to be i n conjunction with the case history quite reliable for the diagnosis of all ergy to hazelnut.