Detection and inhibition of IgE antibodies reactive with cross-reactive carbohydrate determinants in an ELISA for allergen-specific IgE in horses.

BACKGROUND: It has been demonstrated that immunoglobulin (Ig)E specific for cross-reactive carbohydrate determinants (CCD) is present in the serum of sensitized humans, dogs and cats, and that these CCD-specific antibodies might confound serological testing. HYPOTHESIS/OBJECTIVE: The objective was to determine whether or not CCD-reactive antibodies occur in horses and to investigate the prevalence of CCD-reactive IgE antibodies in equine sera using a monoclonal cocktail-based enzyme-linked immunosorbent assay designed to detect allergen-specific IgE in horses, and to evaluate a means for successful inhibition of these CCD. METHODS AND MATERIALS: Sera from 28 horses suspected of clinical allergy were evaluated, with and without a proprietary inhibitor which contains carbohydrates derived from bromelain (BROM-CCD), using a panel of 72 allergens that include 15 grasses, 17 trees, nine weeds, five mites, 12 fungi, 12 insects and two environmental allergens. RESULTS: Twenty-five samples were shown to be reactive to at least one of the allergens, and 15 were reactive to 10 allergens or more. BROM-CCD had minimal effect on the mite reactivity in any of the positive samples; however, substantial inhibition for pollen allergens (trees, grasses and weeds) was demonstrable. Reduction in signal to pollens ranged from 20% to 100% for samples that were inhibited by CCD-BROM. CONCLUSIONS AND CLINICAL IMPORTANCE: These results demonstrate that CCD-reactive IgE antibodies are evident in horses and that BROM-CCD can be effective in reducing reactions with these irrelevant carbohydrates and will likely yield a more accurate in vitro allergen reactivity profile for selection of allergens included in an immunotherapeutic regime.

Detection and Inhibition of IgE for cross-reactive carbohydrate determinants evident in an enzyme-linked immunosorbent assay for detection of allergen-specific IgE in the sera of dogs and cats.

BACKGROUND: It has been demonstrated recently that immunoglobulin (Ig)E specific for cross-reactive carbohydrate determinants (CCD) is present in the serum of allergen-sensitized dogs and cats, and that these CCD-specific antibodies might confound serological testing. HYPOTHESIS/OBJECTIVE: The objective was to document the prevalence of CCD detectable in a monoclonal cocktail-based enzyme-linked immunosorbent assay designed for the detection of allergen-specific IgE in the sera of dogs and cats, and to define a means for successful inhibition of these CCD. METHODS AND MATERIALS: The incidence of reactivity to bromelain and a commercially available inhibitor of carbohydrate-specific antibodies (RIDA-CCD) was evaluated in 100 dog sera samples before and after inhibition with RIDA-CCD and a proprietary inhibitor containing carbohydrates derived from bromelain (BROM-CCD). Subsequently, sera from 600 dogs and 600 cats were evaluated using a serum diluent with and without BROM-CCD. RESULTS: Both the RIDA-CCD and BROM-CCD inhibitors demonstrated successful reduction of CCD reactivity, although a more efficient profile of inhibition was evident with BROM-CCD. Mite reactivity in dog and cat sera was largely unaffected; however, substantial inhibition for pollen allergens (trees, grasses and weeds) was shown. After BROM-CCD inhibition, 1% of canine samples and 13% of feline samples were rendered completely negative for allergen reactivity. CONCLUSIONS AND CLINICAL IMPORTANCE: The results demonstrate that BROM-CCD is effective in reducing reactions with irrelevant carbohydrates, and that inhibition of CCD reactivity might substantially alter the outcome of the in vitro reactivity profile used for selection of allergens to be included in an immunotherapeutic regime.