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 pea nut allergies, but despite the steady advancement in our understanding of a topic immune responses and the increasing number of deaths each year from p eanut anaphylaxis, there is still no safe, effective, specific therapy for the peanut-sensitive individual. Immunotherapy would be safer and more effe ctive if the allergens could be altered to reduce their ability to initiate an allergic reaction without altering their ability to desensitize the all ergic patient. Methods: The cDNA clones for three major peanut allergens, A ra h 1,Ara h 2, and Ara h 3, have been cloned and characterized. The IgE-bi nding epitopes of each of these allergens have been determined and amino ac ids critical to each epitope identified. Site-directed mutagenesis of the a llergen cDNA clones, followed by recombinant production of th e modified al lergen, provided the reagents necessary to test our hypothesis that hypoall ergenic proteins are effective immunotherapeutic reagents for treating pean ut-sensitive patients. Modified peanut allergens were subjected to immunobl ot analysis using peanut-positive patient sera IgE, T cell proliferation as says, and tested in a murine model of peanut anaphylaxis. Results: in gener al, the modified allergens were poor competitors for binding of peanut-spec ific IgE when compared to their wild-type counterpart. The modified allerge ns demonstrated a greatly reduced IgE-binding capacity when individual pati ent serum IgE was compared to the binding capacity of the wild-type allerge ns. In addition, while there was considerable variability between patients, the modified allergens retained the ability to stimulate T cell proliferat ion. Conclusions: These modified allergen genes and proteins should provide a safe immunotherapeutic agent for the treatment of peanut allergy. Copyri ght (C) 2001 S. Karger AG, Basel.