Bet v 1 homologues in strawberry identified as IgE-binding proteins and presumptive allergens.
BACKGROUND
No strawberry allergen has so far been identified and characterized.


METHODS
Serum samples were collected from patients with a suggestive case history of adverse reactions to strawberry and other fruits. Extracts from fresh and frozen strawberries were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), Western blotting and mass spectrometry. Patient blood samples were analysed for inhibition of IgE binding and basophil degranulation.


RESULTS
Several IgE-binding proteins could be detected. In more than half of the patient sera, a 20/18-kDa doublet band was observed in Western blotting. These two bands were excised and analysed by mass spectrometry showing the presence of proteins belonging to the Bet v 1 family of allergens. Inhibition of the IgE binding to the 20/18-kDa doublet was obtained by addition of two recombinantly expressed allergens belonging to the Bet v 1 family (Bet v 1 and Mal d 1) and strawberry protein extract. In a cell-based assay of patient blood samples, basophil degranulation could be induced by strawberry protein extract and by Bet v 1 and Mal d 1.


CONCLUSIONS
We conclude that strawberry homologues to Bet v 1 may be allergens of importance for adverse reactions to strawberry.
Karlsson
A L
AL
SIK--The Swedish Institute for Food and Biotechnology, Gothenburg, Sweden.
Alm
R
R
Ekstrand
B
B
Fjelkner-Modig
S
S
Schiött
A
A
Bengtsson
U
U
Björk
L
L
Hjernø
K
K
Roepstorff
P
P
Emanuelsson
C S
CS
D000328:Adult; D000485:Allergens / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D015549:Basophil Degranulation Test; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005512:Food Hypersensitivity / Q000097:blood / Q000209:etiology / Q000276:immunology*; D031985:Fragaria / Q000009:adverse effects / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010936:Plant Extracts / Q000276:immunology; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D016415:Sequence Alignment
D000485:Allergens; D052179:Antigens, Plant; C501561:Bet v 1 protein, Fragaria; D010936:Plant Extracts; D010940:Plant Proteins; D007073:Immunoglobulin E