Analysis of the expression of Fas-L in nasopharyngeal carcinoma tissues.

Nasopharyngeal carcinoma (NPC) is an epithelial cancer with a high incidence in Southeast Asia. How it escapes attack from the host immune system is not fully understood. Recently, pieces of evidence show that Fas-ligand (Fas-L)-mediated apoptosis may be involved in immune privilege of tumours. To determine whether a similar mechanism may exist in NPC, the expression of Fas-L was analysed. Biopsy specimens of the nasopharynx were taken from 27 NPC patients. Histologically, they were either non-keratinizing or undifferentiated carcinomas. Nasopharyngeal biopsies of 11 other patients that proved to have no tumour served as control. The transcripts of Fas-L were detected by reverse transcription-polymerase chain reaction. Localization of Fas-L protein was performed with immunohistostaining using an antibody recognizing human Fas-L. All nasopharyngeal tissues have a similar amount of transcripts of Fas-L. However, the Fas-L protein was detected exclusively on the cell surface of malignant epithelial cells of NPC. The present findings suggest that Fas-L protein may be involved in evading immune attack of NPC.