Effect of Dermatophagoides pteronyssinus Immunotherapy on Upper and Lower Airway Eosinophilic Inflammatory Response to Nasal Allergen Challenge

Purpose It remains unknown whether allergen-specific immunotherapy (AIT) could attenuate airway inflammatory response triggered by allergen exposure. Methods We performed Dermatophagoides pteronyssinus (Der-p) nasal provocation tests (NPTs) in allergic rhinitis (AR) and/or asthma patients without AIT (non-AIT), or at 16, 52, 104, or 156 weeks after Der-p AIT. Rhinitis and asthma visual analog scale (VAS; VAS of nasal symptoms [VAS-NS], VAS of asthma symptoms), the rhinoconjunctivitis quality of life questionnaire (RQLQ), nasal lavage, sputum induction, fractional exhaled nitric oxide (FeNO), nasal airway resistance, pulmonary function, and airway hyperresponsiveness were performed before and after NPT. Results Non-AIT subjects demonstrated significantly higher VAS-NS before and after NPT compared to AIT subjects (P < 0.05). NPT response was positive in 14 (100%) non-AIT, 7 (70%) 16 weeks-AIT, 6 (60%) 52 weeks-AIT, 6 (60%) 104 weeks-AIT, and 2 (20%) 156 weeks-AIT subjects. The NPT grade significantly correlated with AIT duration and baseline RQLQ score (r = −0.561, P < 0.001 and r = 0.525, P < 0.001, respectively). Sputum and nasal lavage eosinophil count, and FeNO in non-AIT subjects were significantly increased 6 hours after NPT (P < 0.05). AIT subjects did not change their sputum or nasal lavage eosinophil count before and after NPT. Subjects with 156 weeks-AIT demonstrated significantly lower levels of sputum and nasal lavage eosinophil count before and after NPT when compared with non-AIT patients (P < 0.05). Sputum eosinophil counts positively correlated with nasal lavage eosinophil counts at baseline and 6 hours after NPT (r = 0.719, P = 0.006 and r = 0.823, P < 0.001, respectively) in non-AIT patients. Conclusion Our results show that AIT can attenuate both upper and lower airway immune response to nasal allergen exposure in patients with AR and/or asthma.