Epstein-Barr virus (EBV)-induced long-term proliferation of CD4+ lymphocytes leading to T lymphoblastoid cell lines carrying EBV.

We have previously demonstrated that Epstein-Barr virus (EBV) strain B95.8 can infect and initiate a partial transcriptional program in both CD4+ and CD8+ lymphocytes (Guan, M. X., R.-D. Zhang, B. Wu, and E. E. Henderson. 1996. J. Virol. 70:7341-7346). Experiments were undertaken to determine whether EBV infection can alter the growth potential of T lymphocytes. Peripheral blood lymphocytes were separated into populations consisting of 99.8% CD4+ and 98.6% CD8+ T lymphocytes by FACS. Infection of these populations with EBV resulted in blastogenesis in both CD4+ and CD8+ populations. Clones were established from the CD4+ population in the presence of interleukin-2. Two of these clones expressed the T cell surface markers CD3 and CD4 and carried the EBV genome. One lymphoblastoid cell line (LCL) had a mixture of CD4+ and CD19+ cells. The T-LCLs harboring the EBV genome in circular form and transcribed mRNA transcripts corresponding to BZLF1, BRLF1, BMLF1, and EBER-1 and -2. Immunofluorescence demonstrated EBNA in the nucleus of T rosette-positive lymphoblasts with an absence of viral capsid antigen expression. In situ hybridization for EBER showed nuclear and cytoplasmic staining in B95.8 cells, whereas EBV-carrying T-LCLs only showed nuclear staining. These results demonstrate that EBV can both infect and induce growth transformation of T lymphocytes, supporting a direct role for EBV in AIDS-related, EBV-associated T cell lymphomas. A better understanding of the EBV transcriptional program during EBV-induced T cell transformation could directly lead to adoptive T cell therapeutic strategies and/or more effective antiviral chemotherapy for EBV-associated T cell lymphoma.