Cytokines and Epstein Barr virus (EBV) genes expression in blood chronic lymphocytic leukaemia (CLL) cells and their immortalised CLL cell lines

We have encountered two unique chronic lymphocytic leukaemia (CLL) patients, PG and NN. Some blood CLL cells of these patients have been infected and carry Epstein Barr virus (EBV) in vivo. In spite of their early-activated G0/G1 stage of post germinal center (GC) memory cells, ex vivo EBV-carrying blood CLL cells of PG clone expressed LMPs and used specific QUK splice for their EBNA1 expression, similar to the EBV-carrying cells of non-B origin. Interestingly, EBV-carrying CLL cells of NN clone expressed LMP2a and used UK-splice for their EBNA1 expression, similar to the in vivo EBV-carrying high density normal B cells in the blood of healthy individuals. The CLL-derived lines but not normal lymphoblastoid cell line (LCL) used QUK- and YUK-splice for their EBNA1 expression. As expected, LCL and their permanent CLL-derived lines used Cp promoter and up-regulated their EBNA2 expression. Blood CLL cells and the CLL-derived cell lines of these patients spontaneously produced cytokines as shown by microarray assay. The types and quantities of cytokines might relate to their CLL origin and viral strain in the given CLL cells. Neither blood CLL nor their CLL-derived cell lines express any detectable apoptosis-inducer ligands, CD95L or Apo 3L. As a consequence of cell cycle progression, CLL-derived cell lines up-regulated their co-stimulator molecules CD80 and apoptosis-related receptor CD95. Since only the rare EBV-carrying CLL cells grew in vitro, the combination of viral genome and cytokines seems to be critical for the outgrowth of EBV-carrying CLL cells over their EBV-negative counterpart in vitro but not in vivo.

Epstein-Barr virus (EBV) gene expression in lymphoid B cells during acute infectious mononucleosis (IM) and clonality of the directly growing cell lines

We examined the patterns of viral gene expression in acute infectious mononucleosis (IM) patients and the clonality of the directly growing EBV-carrying cell lines. Both low- and high-density EBV-carrying B cells obtained from the patients' tonsils expressed EBNA1, EBNA2 and LMP1. Like LCLs and immunoblastic B-cell lymphomas, the in vivo EBV-carrying low-density cells used only the latency III program for viral gene expression. The in vivo EBV-carrying high-density B cells used both the latency I program, as indicated by the QUK-, and the latency III program, as indicated by the YUK-EBNA1. This suggests that the lymphoid tissues contained not only proliferating immunoblasts but also cells programmed for latent viral persistence in vivo. EBV-carrying cells that grew directly into permanent cell lines in the presence of virus-neutralizing antibody and a late viral inhibitor were polyclonal, as indicated by JH rearrangement. Two of the high-density-derived lines had identical JH and TR patterns, indicating a common parental origin. Our investigation indicates that EBV-carrying cells divide and survive in a fully competent immune system during the outbreak of acute IM.

Combined treatment with interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha up-regulates the expression of HLA class I determinants in Burkitt lymphoma lines

Cell lines derived from Epstein-Barr virus (EBV)-positive and EBV-negative Burkitt lymphoma (BL) have a low or defective expression of polymorphic HLA class I determinants compared to EBV-transformed lymphoblastoid cell lines (LCL) of normal B cell origin and are resistant to lysis by cytotoxic T lymphocytes (CTL) specific for the corresponding determinants (M. G. Masucci, S. Torsteinsdottir, J. Colombani, C. Brautbar, E. Klein, and G. Klein, Proc. Natl. Acad. Sci. USA 84, 4567, 1987; S. Torsteinsdottir, C. Brautbar, E. Klein, G. Klein, and M. G. Masucci, Int. J. Cancer, 41, 913, 1988). In order to investigate whether this phenotypic trait of the tumor cells can be modulated by agents known to enhance HLA class I antigen expression, pairs of LCL and BL lines were cultured in the presence of recombinant human interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha. Three low HLA A11 expressor EBV-negative BL lines, DG 75, BL 28, and BL 41, reacted significantly stronger with the anti-HLA A11 monoclonal antibody (Mab) AUF 5.13 after combined treatment with 500 U/ml IFN-gamma and 500 U/ml TNF-alpha. Reactivity with the AUF 5.13 and with other anti-polymorphic class I Mab's was up-regulated also in in vitro EBV-converted sublines of BL 28 and BL 41. The increment of antigen expression depended on the baseline expression in untreated cells. It was largest for the low expressor lines and decreased proportionally to the level of up-regulation induced by EBV conversion. Up-regulation of HLA A11 was accompanied by induction of sensitivity to HLA A11-specific CTLs in BL 28 and its converted subline E95A BL28 while BL 41 and E95A BL 41 remained resistant. The treatment did not affect significantly HLA A11 expression of two EBV-carrying, low HLA A11 expressor BL lines, WW-1-BL and WW-2-BL, and of the EBV-carrying BL 72 line that had a high spontaneous expression. The results suggest that the down-regulation of class I antigen expression is reversible in some but not all BL lines.