Immunologic characterization of isoforms of Car b 1 and Que a 1, the major hornbeam and oak pollen allergens.
BACKGROUND
Birch pollen allergy is one of the most common causes of spring pollinosis often associated with hypersensitivity reactions to pollen of other Fagales species. Yet, only the major disease eliciting allergens of alder and hazel have been fully characterized. Therefore, the aim of this study was to perform cloning, expression and immunologic characterization of the Bet v 1 homologues from oak (Que a 1) and hornbeam (Car b 1).


METHODS
The isoform pattern of Car b 1 and Que a 1 was analyzed by proteomics using 2D gel electrophoresis and LC ESI-QTOF MS. Isoallergens showing high IgE-binding were cloned and expressed in Escherichia coli. IgE-binding activity of the recombinant proteins was determined by enzyme-linked immunosorbent assay (ELISA) and basophil mediator release assays using serum samples from patients mainly exposed either to oak and hornbeam or to birch pollen. Cross-reactivity of the allergens was further investigated at the T-cell level.


RESULTS
Dominant isoforms of Car b 1 and Que a 1, identified by mass spectrometry, showed different IgE-binding properties when testing Fagales pollen-allergic patients living in birch-free areas as compared to birch-sensitized individuals.


CONCLUSIONS
Tree pollen-allergic patients who are primarily exposed to Fagales pollen other than birch reacted stronger with rCar b 1 and rQue a 1 than with rBet v 1, as determined by inhibition ELISA and basophil mediator release assays. Thus, rCar b 1 and rQue a 1 allergens should be considered for improving molecule-based diagnosis and therapy of tree pollen allergies manifesting in birch-free areas.
Wallner
M
M
Christian Doppler Laboratory for Allergy Diagnosis and Therapy, Department of Molecular Biology, University of Salzburg, Salzburg, Austria.
Erler
A
A
Hauser
M
M
Klinglmayr
E
E
Gadermaier
G
G
Vogel
L
L
Mari
A
A
Bohle
B
B
Briza
P
P
Ferreira
F
F
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000096:biosynthesis* / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D052179:Antigens, Plant; D015549:Basophil Degranulation Test; D029401:Betulaceae / Q000276:immunology*; D015153:Blotting, Western; D003429:Cross Reactions; D015180:Electrophoresis, Gel, Two-Dimensional; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010936:Plant Extracts / Q000276:immunology; D010940:Plant Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000276:immunology*; D011058:Pollen / Q000276:immunology; D020033:Protein Isoforms / Q000276:immunology; D040901:Proteomics; D029963:Quercus / Q000276:immunology*; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000485:Allergens; D052179:Antigens, Plant; C075002:Car b I protein, Carpinus betulus; D010936:Plant Extracts; D010940:Plant Proteins; D020033:Protein Isoforms; D011994:Recombinant Proteins; C061312:Bet v 1 allergen, Betula; D007073:Immunoglobulin E