Effect of topical corticosteroids on seasonal increases in epithelial eosinophils and mast cells in allergic rhinitis: a comparison of nasal brush and biopsy methods

Background Nasal brushing and nasal biopsy are well-tolerated sampling tech niques. Seasonal grass pollen-induced rhinitis is characterized by epitheli al mast cell infiltration and seasonal increases in both epithelial and sub -mucosal eosinophils. Objective To compare the ability of the nasal brush and nasal biopsy techni ques to detect natural seasonal increases in eosinophils and mast cells, an d to assess the influence of topical corticosteroid. Methods Nasal brush samples and nasal biopsies were collected from 46 grass pollen-sensitive seasonal rhinitis patients before the grass pollen season and at the peak of the pollen season following 6 weeks' treatment with eit her fluticasone propionate aqueous nasal spray (200 mu g, twice daily) or p lacebo nasal spray. Results Placebo patients showed seasonal increases in epithelial eosinophil s both with nasal brushing (P<0.0001) and biopsy (P<0.001). Epithelial mast cell numbers also increased during the pollen season as detectable by brus hing (P<0.0001) and biopsy (P<0.03). Changes in cell numbers measured by na sal brushing correlated with those observed with nasal biopsy, both for eos inophils and mast cells (P<0.05). Sub-mucosal eosinophils but not mast cell s also increased during the pollen season (P<0.002). Nasal brushing and bio psy revealed that fluticasone treatment inhibited seasonal increases in epi thelial eosinophils (P<0.00001) and epithelial infiltration by mast cells ( nasal brushing P<0.00001 and nasal biopsy P<0.01). Fluticasone also inhibit ed seasonal increases in submucosal eosinophils (P<0.001) and significantly reduced nasal symptoms (P<0.001). Conclusion Nasal brushing harvests sufficient inflammatory cells from the s urface of the nasal mucosa to be used in lieu of nasal biopsies in observat ion of the effect of drugs on the nasal epithelium.