Objective: The aim of our study was to determine the diagnostic usefulness of a newly developed basophil activation test (BAT) in patients allergic to Dermatophagoides pteronyssinus and pollens. We also analyzed the influence of cetirizine on CD63 upregulation. This popular antihistamine strongly inhibits skin tests, but its impact on BAT sensitivity remains unknown and deserves at least preliminary determination.

Methods: The study sample comprised 22 patients allergic to house dust mite and pollens and 19 healthy controls. All participants underwent skin prick testing and the newly developed fl ow-cytometric basophil activation test. The protocol for allergen-induced basophil CD63 upregulation consisted of whole blood samples that were processed and stained with anti-CCR3/CD63 antibodies added to the buffer at
the beginning of stimulation. Skin prick tests and BAT were performed twice – before and 2 hours after ingestion of 10 mg of cetirizine.

Results: The new BAT is characterized by its short processing time, easy basophil gating, and strong CD63 upregulation with very high sensitivity and excellent specifi city. Our results suggest that allergen-induced CD63 upregulation by higher doses of allergens is not inhibited 2 hours after administration of cetirizine (unlike skin prick tests).

Conclusion: The BAT is a very useful and precise method for the diagnosis of allergy to aeroallergens. It is not infl uenced by cetirizine.

Key words: Basophil. CD63. Allergy. Flow cytometry.