Effect of mycophenolic acid on Epstein-Barr virus infection of human B lymphocytes

Abstract

minute, with a Betaplate scintillation counter (Pharmacia LKB Biotechnology Inc., Piscataway, N.J.). By 3 days postinfection, large cell clumps were evident only in cultures exposed to MPA concentrations of less than 1.0 ,uM, a concentration which inhibited thymidine uptake in both EBV-infected and uninfected cells ( Fig. 1; see below).Indirect immunofluorescence microscopy was performed 4 days after primary B-lymphocyte infection, with monoclonal antibodies PE2 and CS1-4 (27) (donated by L. Young and A. Rickinson, Birmingham, England), which are reactive to EBV nuclear antigen 2 (EBNA-2) and latent membrane protein 1 (LMP-1), respectively. A goat anti-mouse secondary antibody conjugated to fluorescein isothiocyanate (Jackson ImmunoResearch Laboratories Inc., West Grove, Pa.) was added in a secondary step. The results in Table 1 indicate that 2 to 5% and 1 to 2% of the cells expressed EBNA-2 and LMP-1, respectively, following a single round of cell division. This expression of EBNA-2 and LMP-1 was not affected by an MPA concentration of 0.1 or 0.01 ,uM. However, 1.0 ,uM MPA inhibited, but did not completely block, EBNA-2 and LMP-1 expression, thereby reducing the number of EBNA-2-and LMP-1-expressing cells to 1% or less. At concentrations higher than 1.0 ,uM MPA, no further reduction in EBNA-2 and LMP-1 expression was noted, indicating that even high concentrations of MPA could not completely block EBNA-2 and LMP-1 expression. A 50% reduction of EBNA-2 and LMP-1 fluorescence might be expected because of a nonspecific antiproliferative effect of MPA (see below), since the first round of cell division after EBV infection of B lymphocytes in vitro is between 36 and 72 h postinfection (1,19,25). Since both EBNA-2 and LMP-1 are putative mediators of EBV-induced B-cell transformation (12), the inability of MPA to inhibit their expression completely might indicate that MPA cannot prevent initiation of the transforming process.MPA concentrations of 1.0 ,uM and above inhibited the outgrowth of EBV-transformed cells (Fig. 1). However, even this was likely due to an antiproliferative effect of MPA rather than an effect on EBV initiation or maintenance of transformation, since reversibility studies showed that treatment with 2.5 ,uM MPA from the time of infection to 5 days

EBV nuclear antigen EBNALP dismisses transcription repressors NCoR and RBPJ from enhancers and EBNA2 increases NCoR-deficient RBPJ DNA binding

“…EBV nuclear antigen 2 (EBNA2) and EBNALP are the first proteins expressed in latency III infection (2,3). EBNA2 is essential for B-cell transformation (4,5) and for up-regulation of EBV latency III and cell RNA expression through CSL/CBF1/ recombination signal-binding protein for immunoglobulin κJ region (RBPJ), a DNA sequence-specific cell transcription factor (6)(7)(8).…”

Effect of maintenance immunosuppressive drugs on virus pathobiology: evidence and potential mechanisms

“…In vitro , MMF‐associated inhibition of EBV‐transformed B‐cell proliferation was attributed to the antiproliferative effects of MMF rather than any antiviral activity .…”

Infectious risk in pediatric organ transplant recipients: Is it increased with the new immunosuppressive agents?

“…Thus, in a recent retrospective study, the decreased incidence of cryptococcal infections noted in transplanted Indian patients (32) was associated with the use of cyclosporine instead of azathioprine. Mycophenolic acid has been recognized for its ability to inhibit the proliferation of EBV‐transformed B‐cell lines, in vitro (33). A multivariate analysis of 38 519 primary kidney transplants performed between 1997 and 2000 revealed a reduced risk of PTLD in patients with MMF compared with azathioprine (34).…”