Lymphoblastoid cells transfected with c-myc: downregulation of EBV-lytic antigens and impaired response of autologous CD4+ T cells in vitro.
Normal EBV-positive lymphoblastoid B-cell lines (LCL) were transfected with vectors containing the c-myc oncogene (pHEBO-E(mu)-myc) or control vectors (pHEBO-E(mu)) and analyzed for the expression of EBV-lytic and latent antigens. While EBV-latent antigens were normal in the c-myc transfectants, there was an almost complete downregulation of EBV-lytic antigens, including BZLF1, EA(D), gp340 and VCA. These observations were consistently repeated on 6 different LCLs transfected with c-myc. Unlike control LCLs, the c-myc transfectants did not release infectious EBV. PCR analysis demonstrated that BZLF1 mRNA was virtually absent in c-myc transfectants, possibly suggesting that the deregulated c-myc imposed a block in the EBV-lytic cycle at this particular level. c-myc transfectants failed to sustain the proliferative response of autologous CD4+ T-cell clones with specificity for EBV-lytic antigens. However, they regained this capacity after incubation with ultraviolet-inactivated EBV or gp340 antigen in vitro, also indicating that their antigen-presenting capacities were not impaired. c-myc transfectants failed to elicit a secondary proliferative response by autologous CD4+ T cells purified from the peripheral blood of EBV-seropositive donors. Exposure of c-myc transfectants to UV-inactivated EBV again resulted in a proliferative CD4+ T-cell response comparable to that elicited by the control LCLs. Collectively, our data provide evidence for the remarkable ability of an oncogene to influence the life cycle of a virus and to modify the antigenicity of the infected cells.
Fais
F
F
Istituto Nazionale per la Ricerca sul Cancro, IST, Genoa, Italy.
Cutrona
G
G
Ulivi
M
M
Roncella
S
S
Gagliardi
M C
MC
Cornaglia-Ferraris
P
P
Rowe
M
M
Barnaba
V
V
Ferrarini
M
M
D001402:B-Lymphocytes / Q000166:cytology* / Q000502:physiology; D015153:Blotting, Western; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D015536:Down-Regulation; D016259:Genes, myc / Q000276:immunology*; D004854:Herpesvirus 4, Human / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory / Q000502:physiology; D014162:Transfection