Most allergens are proteins or glycoproteins. The carbohydrate portions of glycoprotein (known as cross-reactive carbohydrate determinants [CCDs]) are generally thought to be clinically irrelevant in causing clinical signs; however, CCDs have been known to cause false-positive reactions in allergen-specific immunoglobulin E (IgE) testing in humans and dogs.1-3
This study* evaluated 100 canine serum samples and compared the ability of 2 different CCD inhibitors (RIDA-CCD and BROM-CCD) to reduce nonspecific CCD reactivity in serum samples evaluated for allergen-specific IgE. In addition, dog (n = 600) and cat (n = 600) serum samples were evaluated with and without BROM-CCD to investigate the prevalence of CCD in sera of dogs and cats suspected of having clinical allergy.
BROM-CCD was found to be as or more effective at inhibiting CCD as compared with the commercially available inhibitor, RIDA-CCD. CCDs were present in a significant number of canine and feline samples, and <1% and 13% of serologically positive canine and feline samples, respectively, were completely negative of all allergens after a CCD inhibitor was used. Samples positive to mite mixtures appeared to be true positives, as minimal changes were noted after treatment with a CCD inhibitor. Serum samples positive to grass, tree, and weed mixtures appeared to have a higher rate of false positives, as was seen after the samples were treated with a CCD inhibitor.
