Detection of specific IgE antibodies in the sera of patients allergic to birch pollen using recombinant allergens Bet v 1, Bet v 2, Bet v 4: evaluation of different IgE reactivity profiles.
BACKGROUND
Birch pollen is a significant cause of immediate hypersensitivity among susceptible subjects in temperate climates, affecting 5-54% of the population in western Europe. We examined the specific serum IgE antibodies towards recombinant allergens Bet v 1, Bet v 2 and Bet v 4 in birch-sensitive patients from the province of Cuneo, north-west Italy.


METHODS
Sera were obtained from 372 patients with symptomatic birch pollen-induced allergic rhinitis and/or asthma. A subgroup of these patients suffered from oral allergy syndrome after eating apple. Their sera were evaluated for specific IgE against natural birch pollen and apple extract, as well as Bet v 1, Bet v 2 and Bet v 4 using Pharmacia CAP system (Pharmacia, Uppsala, Sweden).


RESULTS
Of 372 patients 215 (57.80%) had serum-specific IgE towards Bet v 1. A total of 166 sera (44.62%) contained serum-specific IgE to Bet v 2, while Bet v 4 IgE reactivity was documented in 35 subjects (9.41%). Moreover, 146 (39.25%) patients were monosensitized to Bet v 1; 96 (25.81%) patients were monosensitized to Bet v 2; only four sera (1.08%) contained specific IgE towards Bet v 4. Thirty-nine sera (11.02%) did not contain specific IgE to these individual birch pollen allergens. Of course, all 372 sera (100%) had specific IgE against natural birch pollen extract, of which 162 (43.55%) contained specific IgE to apple extract (75.35% of Bet v 1 positive sera).


CONCLUSIONS
In this study we observed that three birch pollen recombinant allergens alone, could sufficiently identify 90% of birch pollen-sensitive patients. Therefore, for a more precise IgE profile of patients allergic to birch, further purified birch pollen allergens (i.e. Bet v 6, Bet v 7, Bet v 8) will be required.
Rossi
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Allergy Unit, National Health Service, Regione Piemonte, Via Carlo Boggio 14, 12100 Cuneo, Italy.
Monasterolo
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Monasterolo
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D000485:Allergens / Q000276:immunology*; D052179:Antigens, Plant; D002135:Calcium-Binding Proteins / Q000276:immunology*; D003285:Contractile Proteins; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E / Q000032:analysis*; D008840:Microfilament Proteins / Q000276:immunology*; D010940:Plant Proteins / Q000276:immunology*; D011058:Pollen / Q000276:immunology; D051304:Profilins; D011994:Recombinant Proteins / Q000276:immunology; D014197:Trees / Q000276:immunology*
D000485:Allergens; D052179:Antigens, Plant; C108867:BETV4 protein, Betula pendula; D002135:Calcium-Binding Proteins; D003285:Contractile Proteins; D008840:Microfilament Proteins; D010940:Plant Proteins; D051304:Profilins; D011994:Recombinant Proteins; C061312:Bet v 1 allergen, Betula; D007073:Immunoglobulin E