Correlation Analysis Between Increased CD63 Expression Detected by Eosinophil Activation Test and sIgE Levels

This study evaluated the diagnostic utility of eosinophil activation testing in allergic rhinitis (AR) by monitoring CD63 and FcεRI expression on peripheral blood eosinophils before and after allergen stimulation. We enrolled 59 AR patients, 35 non-allergic rhinitis (NAR) patients, and 19 healthy controls (HC), stratified by sIgE results and clinical symptoms. Eosinophils were identified via flow cytometry as CCR3+ cells. We quantified baseline eosinophil counts and CD63/FcεRI expression, and then measured their changes following stimulation with 0.1 and 1.0 μg/mL dust mite allergen. Diagnostic accuracy was assessed using ROC analysis and Spearman's correlation with sIgE as the reference standard. AR patients had higher baseline eosinophil counts and CD63 expression than NAR or HC (p < 0.05). FcεRI was elevated in both AR and NAR relative to HC. Upon allergen stimulation, CD63 increased significantly only in AR, and this increase was dose-dependent (p < 0.05); FcεRI showed no response in any group. In this exploratory cohort, CD63 showed promising discriminatory ability, with an AUC of 0.899 (0.1 μg/mL) and 0.994 (1.0 μg/mL); a moderate positive correlation with sIgE was also observed (r = 0.358-0.461). In contrast, FcεRI performed around chance level (AUC 0.534-0.544). The eosinophil CD63 activation test can detect allergen-specific responses in AR and shows a moderate positive correlation with sIgE, suggesting potential as a complementary tool for AR diagnosis.