Molecular composition and biological activity of commercial birch pollen allergen extracts

Authors


Margarete Focke, PhD, Christian Doppler Laboratory for Allergy Research, Division of Immunopathology, Department of Pathophysiology, Center of Physiology, Pathophysiology and Immunology, Medical University of Vienna, A-1090 Vienna, Austria. Tel.:+43-1-40400-5132; fax: +43-1-40400-5130; e-mail: margarete.focke-tejkl@meduniwien.ac.at

Abstract

Background  Commercial extracts used for diagnosis and treatment of allergy are currently prepared from natural allergen sources. The aim of this study was to analyse birch pollen allergen extracts produced for in vivo diagnosis of birch pollen allergy regarding their contents of individual birch pollen allergens (Bet v 1, Bet v 2 and Bet v 4).

Methods  Protein contents were measured and the allergen composition was analysed by immunoblotting using antibody probes specific for Bet v 1, Bet v 2 and Bet v 4 in birch pollen extracts from five manufacturers of allergen extracts. The contents of the major birch pollen allergen, Bet v 1, were quantified with a specific two-site binding enzyme-linked immunosorbent assay with nanogram sensitivity for Bet v 1. The biological activities of the allergen extracts were evaluated by skin prick testing in birch pollen allergic patients and compared with their sensitization profiles.

Results  A more than 10-fold variation regarding total protein contents (23·1–314 μg mL−1) and also regarding the amounts of the major birch pollen allergen, Bet v 1 (1·62–19·6 μg mL−1) was found. The highly cross-reactive Bet v 4 allergen was absent in three of the five tested extracts. Furthermore, varying skin test results were obtained in birch pollen allergic patients with the allergen extracts.

Conclusions  Commercial birch pollen extracts exhibit a considerable variability regarding allergen contents and hence deliver varying in vivo test results. These problems might be overcome with recombinant allergen-based preparations.

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