Molecular basis of pollen-related food allergy: identification of a second cross-reactive IgE epitope on Pru av 1, the major cherry (Prunus avium) allergen.
Birch (Betula verrucosa) pollen-associated food allergy is a well-characterized syndrome, which is due to the cross-reactivity of IgE antibodies to homologous allergens in various foods. One crossreacting area on the major birch pollen allergen Bet v 1 and its homologue in cherry (Prunus avium) Pru av 1 has already been identified. This is the so-called 'P-loop' region, which encompasses amino acid residues around position 45 and is found on the two virtually identical tertiary protein structures. We tried to determine an additional IgE cross-reacting patch on Pru av 1 and Bet v 1. The putative IgE-binding region on Pru av 1 was localized with a mAb (monoclonal antibody) that was generated against Bet v 1, and cross-reacts with several Bet v 1 homologues in food and inhibits the binding of patients' IgE to Pru av 1. mAb reactivity pattern was analysed and amino acid positions 28 and 108 of Pru av 1 were selected and mutated by site-directed mutagenesis. The Pru av 1 mutants were produced as recombinant proteins and characterized for their folding, mAb- and IgE-binding capacity and allergenic potency with a cellular assay using the humanized rat basophilic leukaemia cell line RBL-25/30. Amino acid position 28 is involved in a second major IgE-binding region on Pru av 1 and probably on Bet v 1. The identification of this second major IgE-binding region is an essential prerequisite to understand the phenomenon of cross-reactivity and its clinical consequences, and to produce hypoallergenic proteins for an improved immunotherapy of type I allergy.
Division of Allergology, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, 63225 Langen, Germany.
Regina
R
Wiche
Michaela
M
Gubesch
Herbert
H
König
Kay
K
Fötisch
Andreas
A
Hoffmann
Andrea
A
Wangorsch
Stephan
S
Scheurer
Stefan
S
Vieths
D000485:Allergens / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D052179:Antigens, Plant; D002942:Circular Dichroism; D003429:Cross Reactions / Q000276:immunology*; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D005512:Food Hypersensitivity / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011058:Pollen / Q000276:immunology*; D017433:Protein Structure, Secondary; D027861:Prunus / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D020349:Surface Plasmon Resonance
D000485:Allergens; D000911:Antibodies, Monoclonal; D052179:Antigens, Plant; D000939:Epitopes; C479400:Pru av 1 allergen, Prunus avium; D007073:Immunoglobulin E