Immunologic characterization of monoclonal antibodies that modulate human IgE binding to the major birch pollen allergen Bet v 1.
BACKGROUND
Bet v 1 and homologous proteins represent major allergens for almost 95% of patients allergic to tree pollen and approximately 70% of those allergic to fruits and vegetables. As yet, no continuous (sequential) IgE epitopes have been determined for Bet v 1, and evidence has accumulated that Bet v 1 IgE epitopes belong to the conformational (discontinuous) type.


OBJECTIVE
A panel of 85 mouse monoclonal anti-Bet v 1 antibodies was raised as a tool with which to study the interaction of human IgE antibodies with Bet v 1.


METHODS
The epitopes of selected monoclonal antibodies (mAbs) were characterized by mapping with synthetic overlapping peptides and by cross-competition experiments. Cross-reactivity of Bet v 1-specific mAbs with tree and plant food allergens was investigated by Western blotting. The influence of Bet v 1-specific mAbs on the IgE-Bet v 1 interaction was studied by competition assays with immobilized purified recombinant Bet v 1 and by basophil histamine release experiments.


RESULTS
Antibodies that increased the IgE binding to Bet v 1 up to fivefold could be defined, whereas others inhibited IgE binding to Bet v 1 up to 99% and competed with the Bet v 1-induced histamine release from patients' basophils.


CONCLUSIONS
The activity of the enhancing antibodies is interpreted as a stabilization of Bet v 1 states/IgE epitopes, which are either more accessible for certain IgE antibodies or are recognized with higher affinity. Those mAbs that competed with the Bet v 1-IgE interaction, if humanized or produced as recombinant antibody fragments, might be considered as potential tools for local allergy therapy.
Lebecque
S
S
Schering-Plough, Laboratory for Immunological Research, Dardilly, France.
Dolecek
C
C
Laffer
S
S
Visco
V
V
Denépoux
S
S
Pin
J J
JJ
Guret
C
C
Boltz-Nitulescu
G
G
Weyer
A
A
Valenta
R
R
D000485:Allergens; D000818:Animals; D019138:Antibodies, Blocking / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000096:biosynthesis* / Q000276:immunology* / Q000302:isolation & purification; D000937:Antigen-Antibody Reactions; D052179:Antigens, Plant; D001491:Basophils / Q000276:immunology / Q000378:metabolism; D015153:Blotting, Western; D002846:Chromatography, Affinity; D003429:Cross Reactions / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000032:analysis*; D006636:Histamine Release; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010449:Peptide Mapping; D010940:Plant Proteins / Q000235:genetics / Q000276:immunology*; D011233:Precipitin Tests; D011994:Recombinant Proteins / Q000276:immunology
D000485:Allergens; D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D052179:Antigens, Plant; D000939:Epitopes; D010940:Plant Proteins; D011994:Recombinant Proteins; C061312:Bet v 1 allergen, Betula; D007073:Immunoglobulin E