Changes in basophil activation during immunotherapy with house dust mite and mugwort in patients with allergic rhinitis

Background The basophil activation test (BAT) is a promising tool for monitoring allergen-specific immunotherapy responses. Objective We aimed to investigate the changes in basophil activation in response to the inhalant allergens of house dust mite (HDM) and mugwort pollen during immunotherapy in patients with allergic rhinitis. Methods We enrolled patients with allergic rhinitis who were to receive subcutaneous immunotherapy for the inhalant allergens HDM or mugwort. A BAT was performed to assess CD63 upregulation in response to allergen stimulation using peripheral blood collected from the patients prior to immunotherapy and at 3, 6, 12, and 24 months after beginning immunotherapy. Rhinitis symptoms were evaluated using the rhinitis quality of life questionnaire (RQLQ) at 1-year intervals. Results Seventeen patients (10 with HDM sensitivity, 3 with mugwort sensitivity, and 4 with sensitivity to both HDM and mugwort) were enrolled in the study. Basophil reactivity to HDM did not change significantly during 24 months of immunotherapy. However, a significant reduction in basophil reactivity to mugwort was observed at 24-month follow-up. There was no significant association between the change in clinical symptoms by RQLQ and the change in basophil reactivity to either allergen. The change in allergen-specific basophil reactivity to HDM was well correlated with the change in nonspecific basophil activation induced by anti-FcεRI antibody, although basophil reactivity to anti-FcεRI antibody was not significantly reduced during immunotherapy. Conclusion Suppression of CD63 upregulation in the BAT was only observed with mugwort at 2-year follow-up. However, the basophil response did not reflect the clinical response to immunotherapy.