Plasmacytoid differentiation of Epstein-Barr virus-transformed B cells in vivo is associated with reduced expression of viral latent genes.
The Epstein-Barr virus (EBV)-associated B-cell lymphoproliferative disorders that arise in immunosuppressed individuals are considered to resemble EBV-transformed in vitro lymphoblastoid cell lines (LCLs) with a mature activated B-cell phenotype. In this study of human lymphoproliferative disorders in the severe combined immunodeficiency mouse model, however, we demonstrate that EBV-infected tumor cells are not LCL-like but are predominantly plasmacytoid and that this phenotype correlates with reduced expression of EBV latent genes. B-cell tumors developed within 3-6 weeks after injection of LCLs into severe combined immunodeficiency mice. The tumors and the injected LCLs were analyzed by flow cytofluorometry for B-cell differentiation and activation markers and by ribonuclease protection assay for cellular and viral gene expression. No differences in the expression of CD19 and CD21 were observed. However, a decrease in CD23, CD11a (lymphocyte function-associated antigen LFA-1), and CD58 (LFA-3) expression and an increase in CD38 (a plasma-cell-associated antigen), CD54 (intracellular adhesion molecule ICAM-1), and HLA class I in the tumor cells relative to the LCLs was observed. Two-color flow cytofluorometric analysis showed that the predominant population (> 80%) in LCLs was CD23hi/CD38lo and that the major population in LCL-derived tumors was CD23lo/CD38hi. Cell cycle analysis showed that, in contrast to actively cycling LCLs, the majority of tumor cells had exited the cell cycle and were restricted to G0/G1 phase. Finally, and most important, a reduction in mRNA for the EBV latent genes EBV nuclear antigen 2 (EBNA2) and latent membrane protein (LMP1) was observed in the tumors.
Rochford
R
R
Department of Immunology, Scripps Research Institute, La Jolla, CA 92037.
Hobbs
M V
MV
Garnier
J L
JL
Cooper
N R
NR
Cannon
M J
MJ
D000818:Animals; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000032:analysis*; D000956:Antigens, Viral / Q000235:genetics; D001402:B-Lymphocytes / Q000166:cytology* / Q000502:physiology*; D002453:Cell Cycle; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics; D019309:Epstein-Barr Virus Nuclear Antigens; D005434:Flow Cytometry; D015870:Gene Expression; D005814:Genes, Viral; D005822:Genetic Vectors; D004854:Herpesvirus 4, Human / Q000235:genetics* / Q000276:immunology; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D016133:Polymerase Chain Reaction; D012269:Ribosomal Proteins / Q000235:genetics; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000956:Antigens, Viral; D004268:DNA-Binding Proteins; D019309:Epstein-Barr Virus Nuclear Antigens; D012269:Ribosomal Proteins; C041806:ribosomal protein L32