INCREASED EPITHELIAL-CELL PROLIFERATION IN NASAL POLYPS

Objective: To detect, quantify, and compare respiratory epithelial cel l proliferation in nasal mucosa and polyps from patients with nasal po lyposis. Design: Cohort study. Setting: Patients and samples were sele cted at the Hospital Intercommunal de Creteil (France). Flow cytofluor ometry and immunohistochemistry were performed at Hopitaux Tenon and M ondor (Universite Paris [France] VI et XII). Patients: Twenty-one pati ents undergoing endoscopic ethmoidectomy for treatment of nasal polypo sis. Methods: In 10 cases, epithelial cells were removed from frozen i nferior turbinate mucosa and polyps by mechanical disaggregation and w ere then analyzed by flow cytofluorometry, providing the cell DNA cont ent (propidium iodide labeling) and the percentage of S-phase cells. I n 11 cases, inferior turbinate mucosa and polyps were fixed in formald ehyde and embedded in paraffin. Proliferating cell nuclear antigen exp ression in the epithelium was quantified by immunohistochemistry: a pr oliferating cell nuclear antigen index was calculated for each sample in the basal area, suprabasal area, and full height of the epithelium. Results: All cell populations studied were diploid, and percentages o f S-phase cells were significantly higher in nasal polyps than in muco sa. Proliferating cell nuclear antigen indexes were significantly high er in nasal polyps than in the suprabasal area and full height of the mucosal epithelium. Conclusion: Cell proliferation is increased in epi thelium from nasal polyps. Epithelial damage caused by inflammatory me diators could induce this increased cell proliferation via epithelial repair processes. Inflammatory tells could up-regulate epithelial cell proliferation by secreting growth factors.