Epstein-Barr virus DNA, intermediate filaments and epithelial membrane antigen in nasopharyngeal carcinoma

The aim of this study was to investigate the expression of intermediate fil aments (cytokeratin, vimentin), epithelial membrane antigen (EMA) and the p resence of Epstein-Barr virus (EBV) DNA in undifferentiated nasophalyngeal carcinoma (NPC). A high incidence of nuclear signals in NPC was Sound in pr imaries and regional lymph node metastases (70%), using S-35-labelled probe s of EBV plasmids for in-situ hybridization. Keratinizing squamous cell car cinomas were EBV-negative. All carcinomas were immune-reactive for cytokera tin (KL-1). 45% of the carcinomas were positive for vimentin. The expressio n of epithelial membrane antigen was restricted to epithelial cells and red uced in NPC as compared to the distribution pattern of cytokeratin. Both EB V DNA and vimentin in NPC were present in 9 cases. However, in 5 cases NPG were harboring EBV but were not immunoreactive for anti-vimentin antibodies . In no case was a vimentin-positive NPC also EBV-negative. The identificat ion of cytokeratin subtypes revealed no specific cytokeratin pattern in NPC . The expression of vimentin in NPC is not specific for EBV, but seems to r eflect the loss of intel-epithelial contact in anaplastic carcinomas.