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BACKGROUND: Confirmation of the clinical relevance of sensitisation is important for the diagnosis of allergic rhinitis. OBJECTIVE: To investigate the usefulness of an in vitro basophil activation test and component-resolved diagnosis in distinguishing between symptomatic allergic rhinitis patients and asymptomatic sensitization to house dust mites (HDMs). METHODS: Thirty-six subjects with a positive skin prick test (SPT) for HDM were divided into a symptomatic (n = 17) and an asymptomatic (n = 19) group on the basis of their clinical history and a nasal provocation test. A basophil CD63 response to in vitro stimulation with Dermatophagoides pteronyssinus whole allergen extract and the IgE reactivity profiles for Der p 1, 2, 4, 5, 7, 10, 11, 14, 15, 18, 21, 23 were evaluated. Serum IgE and IgG specific to D pteronyssinus whole allergen extract and total IgE were measured. RESULTS: There were no statistically significant differences in the levels of IgE (IgE levels were higher in symptomatic patients with P = 0.055) and IgG specific to D pteronyssinus and total IgE. Symptomatic patients showed a lower threshold for in vitro basophil activation (3.33 ng/mL vs 33.3 ng/mL), a higher area under the curve (AUC) of basophil activation (171 vs 127) (P = 0.017), a higher response to positive control with anti-FcεRI stimulation (97% vs 79%) (P < 0.001), a recognition of more HDM allergens (4 vs 2) and more frequent sensitization to rDer p 7 (P = 0.016) and rDer p 23 compared to asymptomatic subjects (P = 0.018). There was a positive correlation (r = 0.63; P < 0.001) between the number of recognized allergens and the AUC of basophil activation. CONCLUSION AND CLINICAL RELEVANCE: In the subjects studied, the differences in the basophil response to D pteronyssinus allergen extract, number of recognized HDM allergens and reactivity to rDer p 7 and rDer p 23 distinguish symptomatic from asymptomatic HDM sensitisation better than SPT or allergen extract-specific IgE. Information regarding the clinical relevance of sensitization is important for the prescription of allergen-specific immunotherapy.