Epstein-Barr virus in B-cell non-Hodgkin's lymphomas: unexpected infection patterns and different infection incidence in low- and high-grade types.

Two hundred and eight cases of B-cell non-Hodgkin's lymphoma (B-NHL) occurring in Europeans without any signs of HIV infection were investigated for their association with an Epstein-Barr virus (EBV) infection. The polymerase chain reaction (PCR) was applied for EBV-DNA detection, in situ hybridization (ISH) for the cellular localization of EBV-encoded small nuclear RNAs (EBER) and immediate-early RNAs (BHLF), and immunohistology (IH) for the detection of EBV-encoded latent membrane protein (LMP) and EBV nuclear antigen 2 (EBNA2) expression. PCR and EBER-ISH produced congruent results in those cases with amplifiable DNA. EBV was present overall in 26 per cent (54/208) of the B-NHL cases. Through EBER-ISH, the virus could be localized merely in rare non-neoplastic bystander lymphocytes in 27 and additionally in tumour cells of 27 cases. Unexpectedly, the proportion of EBV-infected tumour cells present in the different cases varied between 1 and 100 per cent. All but three of the cases with infected tumour cells were of high-grade malignancy. Correlation with the morphological and immunological tumour phenotype revealed that all cases with more than 80 per cent EBER-positive tumour cells were either B-anaplastic large cell lymphomas (B-ALCL), sporadic Burkitt's lymphomas, or B-NHLs with partial or full plasmacellular differentiation. LMP was consistently absent from Burkitt's lymphomas and constantly expressed in B-ALCLs with EBER-positive tumour cells, while in all other instances it varied greatly and was rarer than EBER expression.(ABSTRACT TRUNCATED AT 250 WORDS)