Evaluating the Pathogenic Potential of IgE Targeting Cross-Reactive Carbohydrate Determinants in Dogs

Cross-reactive carbohydrate determinants (CCDs) are complex N-glycans shared among allergens of plant, insect venom, and nematode origin. In allergic humans, IgE anti-CCD often develop and cause discrepancies between serological and skin tests. Overall, CCD-IgE are believed to be of low pathogenic relevance. IgE-targeting CCDs are also detected in companion animals, but their pathogenic potential and biological relevance are unknown. Herein, we first establish that, in 34 dogs with atopic dermatitis, the presence of serum anti-CCD IgE was detected in 14 pets (41.2%). In dogs, as in humans, IgE-targeting CCDs are heterogeneous, as they differentially recognized four distinct CCD-expressing proteins. The presence of CCD-IgE was associated with a higher and more frequent recognition of plant extracts in serological but not intradermal tests. Two different CCD-expressing proteins did not elicit immediate reactions when injected intradermally in dogs with detectable serum anti-CCD IgE. Similarly, two different CCD-expressing proteins did not induce the activation of mast cells passively transferred with canine anti-CCD IgE. Altogether, these results suggest that in dogs, as in humans, anti-CCD IgE are likely to have little pathogenic potential and blocking them in allergen-specific IgE serological tests is warranted to avoid false-positive results to plant extracts.