Depletion of specific cockroach allergens may not affect overall allergenicity determinations

Assays of allergen potency may measure specific allergens or overall allergenicity. We wanted to determine whether depletion of specific allergens in German cockroach allergen extract affects overall allergenicity by competition ELISA We selectively adsorbed the allergens Bla g 1 and Bla g 2 from German cockroach extract using allergen-specific rabbit IgG on a Protein G Sepharose column. The effect of adsorption on the extracts was determined by three different methods: a two-site ELISA for Bla g 1 and Bla g 2 using monoclonal antibodies (Indoor Biotechnology, Charlottesville, Virginia), a direct ELISA for Bla g 1 and Bla g 2 using hyper-immune rabbit serum as the detection antibody, and overall allergenicity by an IgE competition ELISA using a human allergic serum pool. Bla g 1 was specifically reduced by 91% and Bla g 2 was specifically reduced by 87%, as measured by two-site ELISA or direct ELISA, following adsorption. However, no loss in overall allergenicity was detected by competition ELISA. Measures of overall allergenicity may not detect the loss of specific allergens.