Nasal cytology identifies allergic rhinitis phenotypes for managing allergen immunotherapy in clinical practice

Backgrounds: Allergic rhinitis (AR) and non-allergic rhinitis with eosinophils (NARES) share type 2 inflammation characterized by nasal eosinophilic infiltrate. Allergen immunotherapy (AIT) is the unique specific treatment for AR, but some patients do not respond. AIT failure may depend on possible comorbidity, mainly concerning NARES. Methods: In all, 33 patients (15 men, mean age 44 years) with AR due to house dust mites allergy were enrolled and treated with sublingual AIT using a monomeric allergoid (LAIS). AIT lasted 3 years. Symptom perception was assessed by visual analog scale (VAS). Symptoms included nasal obstruction, rhinorrhea, sneezing, cough, and olfaction. Nasal cytology evaluated the presence of eosinophils. Patients were evaluated at baseline, after 6 months, and after 1, 2, and 3 years. Objective: The current study aimed at investigating the role of nasal cytology in identifying non-responders to AIT. Results: A total of 28 patients significantly (p < 0.001) improved already after 6 months and showed a progressive reduction of eosinophilic infiltrate (p < 0.001). The 5 non-responder patients continued to experience symptoms, and consistent nasal inflammation did not disappear. Conclusion: Nasal cytology is a fruitful tool to identify non-responder to AIT and phenotype mixed rhinitis, such as AR associated with NARES. Therefore, nasal cytology is useful in AIT management, mainly in non-responders.