Expression of the Epstein-Barr virus latent membrane protein in nasopharyngeal carcinoma biopsy specimens.

It has been known for some time that the Epstein-Barr virus (EBV) is associated with nasopharyngeal carcinoma (NPC). The tumor cells are known to harbor EBV in a latent state. Latently-infected B cells that have become growth transformed by EBV in vitro express some 10 antigens, two of which (Epstein-Barr nuclear antigen 2 [EBNA2] and the latent membrane protein [LMP]) are associated with cellular transformation. We evaluated the expression of these two EBV antigens in NPC by probing tissue sections with monoclonal antibodies. We found that EBNA2 was not expressed and that LMP was expressed in seven of nine biopsy specimens. It is therefore postulated that either there are subsets of NPC or that LMP may be involved only in certain stages of tumor formation.