EPSTEIN-BARR-VIRUS IS LOCALIZED IN THE TUMOR-CELLS OF NASAL LYMPHOMAS OF NK, T-CELL OR B-CELL TYPE

Seven cases of nasal lymphoma were studied to identify the lineage of Epstein-Barr virus (EBV)(+) cells using dual-labelling methods. Five cases were phenotypically and genotypically of natural killer cell (NK) type with germ-line configuration of T-cell receptor (TcR) beta-chain gene and immunoglobulin heavy-chain joining region (Igj(H)) gene, with one case each of T- and B-cell type showing rearranged TcR beta or Igj(H) and lambda-light chain genes respectively. EBV genome was clonal in all these cases except in the B-cell case where its clonality was undeterminable. Using in situ hybridization (ISH) for EBV-encoded small nuclear RNA I and 2 (EBER), signal was detected in 45% to 88% of nucleated cells in the tumours. Immunostaining for EBV latent membrane protein-1 (LMP) also revealed numerous LMP(+) cells in 3/5 NK-type cases and the T- and B-cell cases. Using ISH for EBER combined with immunostaining for CD markers and double immunohistochemisty for LMP and CD markers, the predominant lineage of the EBV(+) cells was identified as: CD2(+)CD3(-)CD19(-)CD20(-) CD45RO(+/-)CD56(+)CD68(-) in the NK-type cases, CD2(+)CD3(+/-)CD19(-)CD20(-) CD45R0(+)CD56(-)CD68(-) in the T-cell case and CD20(+)CD45R0(-)CD68(-) in the B-cell case, in agreement with the genotype and phenotype of each tumour. These results show that, in EBV(+) nasal lymphomas of NK, T- or B-cell lineage, EBV was consistently associated with the tumour-cell population and support the view that EBV serves a promoting role in the pathogenesis of different types of EBV(+) nasal lymphoma. (C) 1995 Wiley-Liss, Inc.