Seasonal changes in nasal cytology in mite-allergic patients

Background: House dust mites (HDMs) are a major cause of allergic rhinitis (AR) and asthma worldwide. Recent studies suggested that the allergen load presents seasonal modifications, giving rise to seasonal variation in nasal inflammation and symptoms. The aim of this study was to evaluate by nasal cytology whether nasal inflammation in mite-allergic patients changes with the seasons of the year. Methods: The study included 16 patients (seven males and nine females, mean age 38.1 years) with persistent AR caused by monosensitization to HDMs. Nasal cytology was performed in all patients once monthly for 1 year. Results: Nasal cytology showed that the cells most commonly detected in the nasal mucosa were neutrophils. During the period from October to April, a peak in the number of neutrophils and also the presence of significant numbers of eosinophils, mast cells, and lymphocytes/plasma cells were found, which shows the occurrence of more intense inflammation during these months. Conclusion: Nasal cytology provides useful data in detecting nasal inflammation and its association with the clinical stage of AR. The seasonal variations in nasal cytology are likely to be induced by the fluctuations in the HDM allergen that have been uncovered in recent investigations.