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

Nasopharyngeal carcinoma (NPC) is an epithelial cancer with a high incidenc e in Southeast Asia. How it escapes attack from the host immune system is n ot fully understood. Recently, pieces of evidence show that Fas-ligand (Fas -L)-mediated apoptosis may be involved in immune privilege of tumours. To d etermine whether a similar mechanism may exist in NPC, the expression of Fa s-L was analysed. Biopsy specimens of the nasopharynx were taken from 27 NP C patients. Histologically, they were either non-keratinizing or undifferen tiated carcinomas. Nasopharyngeal biopsies of 11 other patients that proved to have no tumour served as control. The transcripts of Fas-L were detecte d by reverse transcription-polymerase chain reaction. Localization of Fas-L protein was performed with immunohistostaining using an antibody recognizi ng human Fas-L. All nasopharyngeal tissues have a similar amount of transcr ipts of Fas-L. However, the Fas-L protein was detected exclusively on the c ell surface of malignant epithelial cells of NPC. The present findings sugg est that Fas-L protein may be involved in evading immune attack of NPC. (C) 1999 Elsevier Science Ltd. All rights reserved.