Overexpression of Fas-ligand in human nasal polyps

Apoptosis mediated through the Fas/Fas-L system is essential in regulating immune function, developing organs, and conferring immune privilege. To illustrate the role of the Fas/Fas-L system in the pathogenesis of human nasal polyps, we investigated the transcripts and protein level of the Fas-L gene in 8 human nasal polyp tissues and 7 nasal turbinate mucosa specimens using reverse transcription-polymerase chain reaction and Western blotting. Localization of Fas-L was performed with immunohistochemistry. The transcripts of the Fas-L gene were detected at similar levels in both polyps and nasal mucosa. There was a significant overexpression of Fas-L protein on nasal polyps compared to nasal mucosa. Fas-L-positive cells were localized on the epithelial layers of cystically dilated glands and the down-growing epithelium of nasal polyps. Fas-L may play an important role in the pathogenesis of human nasal polyps, including cystic degeneration of submucosal glands and conferring of immune privilege to nasal polyp formation.