Deleterious effects of electron beam radiation on allergen extracts

Background: The recent threat to the public posed by the dissemination of Bacillus anthracis through the US postal system has resulted in increased security measures, including electron beam irradiation for the sterilization of some mail. The deleterious effects of electron beam radiation on biological products are not fully understood. Objective: The purpose of this investigation was to assess the effect of electron beam radiation, as currently used to sterilize packages and mail in the United States, on several standardized or characterized allergen extracts. Methods: Selected irradiated extracts were analyzed for allergen content and potency by SDS-PAGE, immunoblot, and ELISA (including inhibition) and compared with untreated extracts. Results: The compositions and immunochemical potencies of these products were altered significantly by irradiation treatment. Physical changes to native protein structures observed after electrophoretic separations coincided with near-complete loss of allergenic and antigenic epitopes present on major and minor allergens, according to ELISA and immunoblot comparisons with untreated extracts. Conclusions: These results indicate that extracts subjected to electron beam sterilization conditions are likely to contain modified component structures and properties that might compromise the clinical effectiveness of these products.