[Prevalance of immunoglobulin E against cross-reactive carbohydrate determinants (CCD) and impact of a blocker in seasonal allergy tests].

OBJECTIVES

Cross-reactive carbohydrate determinants (CCD) cause false positive/clinically irrelevant results in seasonal in vitro allergy tests due to the binding of immunoglobulin IgE against CCD (anti-CCD IgE).There is no study regarding the presence of this phenomen in cats. The aim of this study was to investigate the prevalence of polysensitization in serum samples and evaluate the impact of a CCD inhibitor/blocker in multi-positive seasonal allergy test results in cats.

MATERIALS AND

METHODS

A total of 472 feline sera, submitted from July 2017 to June 2018 for seasonal in vitro allergy test via ELISA Fc-Ε receptor technology, were studied. Samples were grouped into polysensitized (group A) and non-polysensitized (group B). Polysensitized samples (A) were retested after adding a modified glycoprotein plants extract (blocker). To determine the impact of the blocking to each allergen, the results in 48 randomly selected samples in cats prior- and post-blocking were investigated.

RESULTS

Polysensitization to seasonal allergens was diagnosed in 137 (29 %) samples. No discrepancy in presence of polysensitization was seen in different seasons. Blocking eliminated the binding of anti-CCD IgE and produced either negative test results (49 %) or a decrease of 1-4 reaction classes (41 %) which is indicative of the simultaneous presence of clinically relevant allergen specific IgE. Total negative reactions after blocking were less common in 6-grass mix (31 %), rye (23 %) and sheep sorrel (25 %) in comparison to willow und birch-hazel (67 %), mugwort-ragweed und nettle (65 %), as well as English plantain (54 %).

CONCLUSION AND CLINICAL RELEVANCE: In order to improve the quality of seasonal in vitro allergy test, blocking should be employed in cases of polysensitized results resulting in an avoidance of the administration of non-offending allergens during allergen-specific immunotherapy (ASIT).