BCL-6 PROTEIN EXPRESSION IN AIDS-RELATED NON-HODGKINS-LYMPHOMAS - INVERSE RELATIONSHIP WITH EPSTEIN-BARR VIRUS-ENCODED LATENT MEMBRANE PROTEIN-1 EXPRESSION

This study aimed at investigating the expression of the BCL-6 protein in acquired immune deficiency syndrome (AIDS)-related non-Hodgkin's ly mphomas (AIDS-NHLs) and at comparing the expression pattern with the p resence of Epstein-Barr virus (EBV) infection of the tumor clone. A to tal of 34 AIDS-NHL biopsies, including 16 AIDS-related diffuse large-c ell lymphomas (AIDS-DLCLs) and 18 AIDS-related small-noncleaved-cell l ymphomas (AIDS-SNCCLs) as well as 7 AIDS-SNCCL cell lines were immunos tained with a BCL-6-specific monoclonal antibody. Expression of BCL-6 protein was detected in 9 of 16 AIDS-DLCLs, 18 of 18 AIDS-SNCCLs, and 3 or 7 AIDS-SNCCL cell lines. Expression of BCL-6 among AIDS-NHLs occu rred independently of the presence of molecular lesions of the bcl-6 g ene. Notably, among EBV-positive AIDS-NHL biopsies and cell lines, exp ression of BCL-6 was mutually exclusive with the expression of EBV-enc oded transforming antigen latent membrane protein-1. The mutual exclus ion between BCL-6 and latent membrane protein-1 expression was further confirmed by in vitro superinfection experiments of an AIDS-SNCCL cel l line originally devoid of EBV sequences. Overall, the frequent assoc iation between AIDS-NHLs and expression of BCL-6, a protein selectivel y expressed by germinal center B cells, suggests that these lymphomas may originate from the germinal center.