Identification of B-cell epitopes of Bet v 1 involved in cross-reactivity with food allergens.
BACKGROUND
The pollen-food syndrome (PFS) is an association of food allergies to fruits, nuts, and vegetables in patients with pollen allergy. Mal d 1, the major apple allergen, is one of the most commonly associated food allergens for birch pollen-allergic patients suffering from PFS. Although the reactions are due to cross-reactive IgE antibodies originally raised against pollen Bet v 1, not every Bet v 1-allergic patient develops clinical reactions towards apple.


OBJECTIVE
We speculate that distinct IgE epitopes are responsible for the clinical manifestation of PFS. To test this hypothesis we grafted five Mal d 1 stretches onto Bet v 1. The grafted regions were 7- or 8-amino acids long encompassing amino acids residues previously shown to be crucial for IgE recognition of Bet v 1.


METHODS
A Bet v 1-Mal d 1 chimeric protein designated BMC was expressed in Escherichia coli and purified to homogeneity. IgE reactivity of BMC was tested with patients' sera originating from (i) Bet v 1-allergic patients displaying no clinical symptoms upon ingestion of apples; and (ii) Bet v 1-allergic patients displaying allergic symptoms upon ingestion of apples and other Bet v 1-related foods.


CONCLUSIONS
Compared to birch pollen-allergic individuals, patients suffering from PFS showed significantly higher IgE reactivity with BMC (chimeric protein). The results suggest that the Mal d 1 regions grafted onto the Bet v 1 sequence comprise important IgE epitopes recognized by Bet v 1-allergic patients suffering from allergy to apples.
Klinglmayr
E
E
Department of Molecular Biology, University of Salzburg, Austria.
Hauser
M
M
Zimmermann
F
F
Dissertori
O
O
Lackner
P
P
Wopfner
N
N
Ferreira
F
F
Wallner
M
M
D000485:Allergens / Q000276:immunology*; D052179:Antigens, Plant; D029662:Betula / Q000276:immunology; D015153:Blotting, Western; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D018985:Epitopes, B-Lymphocyte / Q000276:immunology*; D005512:Food Hypersensitivity / Q000276:immunology*; D006801:Humans; D027845:Malus / Q000009:adverse effects / Q000276:immunology; D010940:Plant Proteins / Q000276:immunology*; D011058:Pollen / Q000276:immunology; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000276:immunology
D000485:Allergens; D052179:Antigens, Plant; D018985:Epitopes, B-Lymphocyte; C095551:MALD1 protein, Malus domestica; D010940:Plant Proteins; D011994:Recombinant Proteins; C061312:Bet v 1 allergen, Betula