IgE reactivity to Api g 1, a major celery allergen, in a Central European population is based on primary sensitization by Bet v 1

Background: Up to 70% of patients with tree pollen allergy display allergic symptoms when eating certain fruits and vegetables. Homologous proteins wi th allergenic features are present in a wide range of plant species and can cause allergic reactions. Objective: The aim of this study was to evaluate recombinant Api g 1, a maj or celery allergen, for In vivo and in vitro diagnosis of celery allergy in populations from Davos, Switzerland, and Montpellier, France. Methods: A group of patients with celery and birch pollen allergy from Davo s was tested, and the results from those tests were compared with results f rom a group of patients allergic to celery from Montpellier. Skin prick tes ts were performed with a commercial celery extract, crude celery, and purif ied recombinant Api g 1. Quantitative and qualitative serology was done wit h natural and recombinant allergens by means of RASTs and immunoblotting. Results: Recombinant Api g 1 allowed accurate in vivo diagnosis of celery a llergy in all patients from the Swiss group. RAST results with celery extra ct were negative in 8 of 24 patients; results of immunoblotting with celery extract were negative in 4 of 24 patients, and results of immunoblotting w ith recombinant (r)Api g 1 were negative in 8 of 24 patients. In the French group 11 of 12 patients had a positive skin reaction with crude celery ext ract, but only 2 patients reacted with rApi g 1. RAST results for celery we re positive in 8 of 12 patients. In immunoblotting experiments 8 patient se ra displayed IgE directed against various celery allergens, whereas no pati ents sera had rApi g I-specific IgE. Conclusion: Our results document that rADi g 1 allows accurate in vivo diag nosis only in areas where birch trees are common. In areas where no birch t rees grow, primary sensitization takes place through different pollen aller gens (eg, mugwort pollen). Moreover, it became evident that birch pollen an d celery allergy are highly related in Central Europe, whereas in Southern Europe the mugwort-celery type is predominant.