Stable transfection of Epstein-Barr virus (EBV) nuclear antigen 2 in lymphoma cells containing the EBV P3HR1 genome induces expression of B-cell activation molecules CD21 and CD23

Abstract

A set of B-cell activation molecules, including the Epstein-Barr virus (EBV) receptor CR2 (CD21) and the B-cell activation antigen CD23 (Blast2/Fc epsilon RII), is turned on by infecting EBV-negative B-lymphoma cell lines with immortalizing strains of the viruslike B95-8 (BL/B95 cells). This up regulation may represent one of the mechanisms involved in EBV-mediated B-cell immortalization. The P3HR1 nonimmortalizing strain of the virus, which is deleted for the entire Epstein-Barr nuclear antigen 2 (EBNA2) protein open reading frame, is incapable of inducing the expression of CR2 and CD23, suggesting a crucial role for EBNA2 in the activation of these molecules. In addition, lymphoma cells containing the P3HR1 genome (BL/P3HR1 cells) do not express the viral latent membrane protein (LMP), which is regularly expressed in cells infected with immortalizing viral strains. Using electroporation, we have transfected the EBNA2 gene cloned in an episomal vector into BL/P3HR1 cells and have obtained cell clones that stably express the EBNA2 protein. In these clones, EBNA2 expression was associated with an increased amount of CR2 and CD23 steady-state RNAs. Of the three species of CD23 mRNAs described, the Fc epsilon RIIa species was preferentially expressed in these EBNA2-expressing clones. An increased cell surface expression of CR2 but not of CD23 was observed, and the soluble form of CD23 molecule (SCD23) was released. We were, however, not able to detect any expression of LMP in these cell clones. These data demonstrate that EBNA2 gene is able to complement P3HR1 virus latent functions to induce the activation of CR2 and CD23 expression, and they emphasize the role of EBNA2 protein in the modulation of cellular gene implicated in B-cell proliferation and hence in EBV-mediated B-cell immortalization. Nevertheless, EBNA2 expression in BL/P3HR1 cells is not able to restore the level of CR2 and CD23 expression observed in BL/B95 cells, suggesting that other cellular or viral proteins may also have an important role in the activation of these molecules: the viral LMP seems to be a good candidate.

Induced CD25 Expression in a Human B‐Lymphoma Cell Line Transfected with the Epstein‐Barr Virus Nuclear Antigen 2 Gene

“…Then, expression of the eight cell surface antigens on the cells which expressed both EBNA-2 and LMP or LMP alone was quantitatively analyzed ( Table 2). An increased expression of CD21 and CD23 such as reported from other laboratories (8,48) was hardly observed on any cell clone which we made and examined in this study. It should, however, be noted that the experimental data does not necessarily exclude a possibility of CD21 increase in the cell clones, since the epitope to the anti-CD21 monoclonal antibody B2 was not detected on several CD21-positive B cell lines (3).…”

Biology and adoptive cell therapy of Epstein‐Barr virus‐associated lymphoproliferative disorders in recipients of marrow allografts

“…Since this protein also interacts with the activated notch protein which plays a roie in the induction of T-cell leukemias (42), it has been hypothesized that EBNA-2, through its interaction with RBPJ-K, might affect the function of several genes in the notch gene-signalling pathway which may contribute to transformation and immortahzation. EBNA-2 also transactlvates the expression of CD2 1 (EBV receptor), and the B-cell activation antigen CD23 (43,44). thereby enhancing the cell's sensitivity to B-cell growth factors.…”

Epstein-Barr virus latent membrane protein (LMP1) is not sufficient to maintain proliferation of B cells but both it and activated CD40 can prolong their survival.

“…It modulates the expression of the B cell activation markers CD21 and CD23 and the tyrosine kinase c-fgr (Calender et al, 1987;Wang,F. et al, 1987;Cordier et al, 1990; Knutson, 1990). In…”