Agreement of serum allergen test results with unblocked and blocked IgE against cross‐reactive carbohydrate determinants (CCD) and intradermal test results in atopic dogs

Abstract

Background -Tests for allergen-specific immunoglobulin E (IgE) are used to select allergens for immunotherapy in atopic dogs. Antibodies against cross-reactive carbohydrate determinants (anti-CCD IgE) have been identified in serum samples of atopic dogs. Their presence in humans is a known cause of clinically irrelevant polysensitization to plant allergens.Objectives -To compare the results of an intradermal test (IDT) and a serum test for allergen-specific IgE, with and without blocking anti-CCD IgE, before testing in dogs.Animals -Thirty-one privately owned dogs with atopic dermatitis.Methods and materials -Dogs were prospectively skin tested and their serum samples were analysed for anti-CCD IgE. An Fc-e receptor-based serum test for allergen-specific IgE was performed with and without blocking anti-CCD IgE.Results -In dogs with negative anti-CCD IgE samples, the agreement between the results of the serum test and the IDT was substantial (j = 0.71). Dogs with positive anti-CCD IgE samples (38.7%) showed no agreement between serum and skin testing (j = À0.35), blocking anti-CCD IgE in those samples resulted in a fair agreement (j = 0.43). Anti-CCD IgE positive sera had multiple positive results for grass and weed allergens, and blocking decreased them markedly.Conclusion and clinical importance -Intradermal testing agreed best with serum testing in dogs with no detectable anti-CCD IgE. Sera containing anti-CCD IgE had no agreement with IDT. Test agreement was improved by blocking the anti-CCD IgE. Apparent serum test polysensitization to plant allergens was associated with anti-CCD IgE.

Serum IgE against cross‐reactive carbohydrate determinants (CCD) in healthy and atopic dogs

“…10 A third study of atopic dogs from Germany, using a third and different assay system, reported a CCD IgE-positive prevalence of 39%. 9 Differences in reported prevalence might easily be explained by differences in patient inclusion criteria, in the assay systems used and perhaps even by regional variation. However, a clear and consistent result, also part of the findings herein, is demonstration that positive anti-CCD IgE in a serum sample from an atopic dog always is associated with positive reactions to pollen allergens.…”

“…4,12 Initial evidence also suggests that this is true in dogs: using a special blocking step to eliminate anti-CCD IgE reactivity in a serological assay leads to better correlation of serology results with those of intradermal testing. 9 When actual concentrations of anti-CCD IgE were examined in atopic versus healthy dogs, it was found that atopic dogs had higher concentrations. This would likely be explained by the fact that atopic dogs are genetically programmed to have immunological responses that are Th2-biased and therefore may have overall higher IgE responses.…”

“…In two published studies, 23 and 39% of serum samples from atopic dogs were positive for anti-CCD IgE antibodies, respectively. 8,9 In an additional published abstract, a prevalence of 73% was reported. 10 The authors are unaware of any published studies investigating the prevalence of anti-CCD IgE in healthy dogs.…”

Atopic dermatitis in West Highland white terriers – part I: natural history of atopic dermatitis in the first three years of life

“…Moreover, the broad definition used herein is similar to those used in other clinical studies. 12,13 It is considered unlikely that the selected broad cAD (bsAD) definition used herein markedly influenced the calculated disease prevalence in WHWT by the time the dogs had reached early adulthood. An overall disease prevalence of 52% in WHWT may be perceived as very high; however, this breed has been shown for a long time to be predisposed to this disease.…”

“…The definition is in keeping with clinical trials. 12,13 The broader definition was used for all analyses.…”