Engineering, characterization and in vitro efficacy of the major peanut allergens for use in immunotherapy.
BACKGROUND
Numerous strategies have been proposed for the treatment of peanut allergies, but despite the steady advancement in our understanding of atopic immune responses and the increasing number of deaths each year from peanut anaphylaxis, there is still no safe, effective, specific therapy for the peanut-sensitive individual. Immunotherapy would be safer and more effective if the allergens could be altered to reduce their ability to initiate an allergic reaction without altering their ability to desensitize the allergic patient.


METHODS
The cDNA clones for three major peanut allergens, Ara h 1, Ara h 2, and Ara h 3, have been cloned and characterized. The IgE-binding epitopes of each of these allergens have been determined and amino acids critical to each epitope identified. Site-directed mutagenesis of the allergen cDNA clones, followed by recombinant production of the modified allergen, provided the reagents necessary to test our hypothesis that hypoallergenic proteins are effective immunotherapeutic reagents for treating peanut-sensitive patients. Modified peanut allergens were subjected to immunoblot analysis using peanut-positive patient sera IgE, T cell proliferation assays, and tested in a murine model of peanut anaphylaxis.


RESULTS
In general, the modified allergens were poor competitors for binding of peanut-specific IgE when compared to their wild-type counterpart. The modified allergens demonstrated a greatly reduced IgE-binding capacity when individual patient serum IgE was compared to the binding capacity of the wild-type allergens. In addition, while there was considerable variability between patients, the modified allergens retained the ability to stimulate T cell proliferation.


CONCLUSIONS
These modified allergen genes and proteins should provide a safe immunotherapeutic agent for the treatment of peanut allergy.
Bannon
G A
GA
Department of Biochemistry and Molecular Biology, Arkansas Children's Hospital Research Institute, Little Rock 72205, USA. bannongarya@exchnage.uams.edu
Cockrell
G
G
Connaughton
C
C
West
C M
CM
Helm
R
R
Stanley
J S
JS
King
N
N
Rabjohn
P
P
Sampson
H A
HA
Burks
A W
AW
D055516:2S Albumins, Plant; D000485:Allergens / Q000235:genetics* / Q000276:immunology*; D000707:Anaphylaxis / Q000517:prevention & control; D000818:Animals; D052179:Antigens, Plant; D010367:Arachis / Q000009:adverse effects*; D003888:Desensitization, Immunologic; D005512:Food Hypersensitivity / Q000276:immunology / Q000628:therapy*; D017343:Genes, Plant; D005818:Genetic Engineering; D006023:Glycoproteins / Q000235:genetics / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000096:biosynthesis / Q000276:immunology; D008213:Lymphocyte Activation; D008565:Membrane Proteins; D051379:Mice; D016297:Mutagenesis, Site-Directed; D010940:Plant Proteins / Q000235:genetics / Q000276:immunology; D055314:Seed Storage Proteins
D055516:2S Albumins, Plant; D000485:Allergens; D052179:Antigens, Plant; C500889:Ara h 1 protein, Arachis hypogaea; C078642:Ara h II protein, Arachis hypogaea; D006023:Glycoproteins; D008565:Membrane Proteins; D010940:Plant Proteins; D055314:Seed Storage Proteins; C118207:allergen Ara h3; D007073:Immunoglobulin E