Investigation of the diagnostic accuracy of basophil activation test for allergic phenotypes of rhinitis

Introduction: Basophil activation test (BAT) might be an alternative to nasal allergen challenge (NAC) to identify the allergic etiology in rhinitis patients. Here, we investigate the diagnostic performance of BAT for allergic phenotypes of rhinitis. Methods: Rhinitis patients and healthy controls were subjected to NAC with Dermatophagoides pteronyssinus (DP), Alternaria alternata (AA), grass (GP) and olive (OP) pollens. Rhinitis subjects also underwent skin prick test (SPT) with relevant allergens. Patients were classified into allergic rhinitis (AR, positive NAC and SPT), local allergic rhinitis (LAR, positive NAC and negative SPT), dual allergic rhinitis (DAR, defined as AR for ≥1 allergen and LAR for ≥1 allergen), and non-allergic rhinitis (NAR, negative NAC and SPT) phenotypes. BAT with DP, AA, GP and OP was conducted in study individuals and compared with NAC results. Results: A total of 47 AR, 31 DAR, 26 LAR, 12 NAR and 21 control subjects were recruited. The best positivity cut-offs of BAT for DP-, AA-, GP- and OP-driven allergy (all phenotypes) were a %CD63 cells of 8.650, 14.250, 26.200, and 12.780, respectively (AUC 0.851, 0.701, 0.887, and 0.921, respectively). Sensitivity, specificity, negative and positive predictive values of BAT (all phenotypes) ranged 43.5%(AA)-83.3%(OP), 88.9%(GP)-100%(AA), 87%(GP)-100%(AA), and 61.1%(DP)-80.0%(pollens), respectively. BAT identified 79%–100% of SPT-positive allergies (AR and DAR), and 25%–75% of SPT-negative allergies (LAR and DAR), while ≤10% of NAR/HC subjects tested positive. BAT positivity correlated with rhinitis severity in LAR patients (p = 0.018), and associated with conjunctivitis (p = 0.015) in allergic subjects. Conclusion: BAT can replace NAC for AR confirmation, and limit the number of NAC required for LAR and DAR diagnosis. BAT can demonstrate sIgE in SPT-negative allergies.