Naturally occurring hypoallergenic Bet v 1 isoforms fail to induce IgE responses in individuals with birch pollen allergy.
BACKGROUND
Engineered hypoallergens are currently being investigated for specific immunotherapy of allergic diseases in preclinical and clinical studies. Naturally occurring hypoallergens have by and large not been considered as a source of vaccine candidates.


OBJECTIVE
Evaluation of the antibody response in atopic individuals induced by birch pollen containing isoforms of the major birch pollen allergen Bet v 1.


METHODS
Isoform-specific antibody isotype responses for Bet v 1.0101, Bet v 1.0401, and Bet v 1.1001 were determined for 35 sera of individuals with birch pollen allergy. Isoform structures were compared and related to IgE-binding inhibitory capacities and induction of mediator release in human Fcvarepsilon receptor transformed rat basophilic leukemia cells.


RESULTS
Bet v 1.0101 induced a predominant IgE response, whereas the significant highest levels of IgG(4) antibodies were directed against Bet v 1.0401. Bet v 1.1001 induced only a minimal antibody response. Structural comparisons revealed that most of the amino acid differences between the isoforms were located on the protein surfaces. IgE induced by Bet v 1.0101 only partly cross-reacted with the 2 other isoforms and bound to them with notably lower affinity. Bet v 1.0401 and Bet v 1.1001 also were poor inducers of mediator release.


CONCLUSIONS
Bet v 1 isoforms possess highly variant immunogenic and allergenic properties. Bet v 1.0101 acts as the sensitizing agent, whereas Bet v 1.0401 and Bet v 1.1001 can induce only a minimal IgE response.
Wagner
Stefan
S
Department of Pathophysiology, Center for Physiology and Pathophysiology, Medical University of Vienna, Vienna, Austria.
Radauer
Christian
C
Bublin
Merima
M
Hoffmann-Sommergruber
Karin
K
Kopp
Tamara
T
Greisenegger
Elli K
EK
Vogel
Lothar
L
Vieths
Stefan
S
Scheiner
Otto
O
Breiteneder
Heimo
H
D000328:Adult; D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D019138:Antibodies, Blocking / Q000097:blood; D052179:Antigens, Plant; D029662:Betula / Q000276:immunology; D045744:Cell Line, Tumor; D002942:Circular Dichroism; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000276:immunology / Q000517:prevention & control; D007073:Immunoglobulin E / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology*; D011058:Pollen / Q000009:adverse effects / Q000276:immunology; D020033:Protein Isoforms / Q000737:chemistry / Q000276:immunology*; D051381:Rats
D000485:Allergens; D019138:Antibodies, Blocking; D052179:Antigens, Plant; D007074:Immunoglobulin G; D010940:Plant Proteins; D020033:Protein Isoforms; C061312:Bet v 1 allergen, Betula; D007073:Immunoglobulin E