[IFN production by Epstein-Barr virus in human mononuclear leukocytes and suppression of the virus-induced transformation by the endogenous interferon].

This study was undertaken to see whether or not interferon (IFN) is produced in infection with Epstein-Barr virus (EBV) and whether or not the IFN suppresses the transformation by EBV. When mononuclear leukocytes were infected with B95-8 EBV, IFN level reached a maximum 24 h after exposure to the virus, and a gradual decrease followed. There were apparent correlations between EBV inoculum size and IFN titer and between cell density and IFN titer. IFN was also induced by UV-inactivated EBV and heat-inactivated EBV, but not by neutralized virus. IFN inducibility varied among donors, but there was no significant difference between EBV-seropositive and -seronegative groups. Cord blood leukocytes, however, responded lower than adults. EBV induced IFN in not only EBV-susceptible B cells but also non-susceptible T and NK cells. The activities of all IFN in this study were stable to acid and heat and exclusively neutralized by anti-human IFN-alpha. IFN production was probably generated by non-specific contact of EBV with the surface of mononuclear leukocytes in a dose-dependent fashion. The efficiency of EBV-transformation was significantly increased by neutralization of the endogenous IFN-alpha with anti-human IFN-alpha. However, there was no difference in appearance of EBV nuclear antigen (EBNA) positive cells at 24 h after EBV infection on incubation with or without IFN-alpha. The transformation of EBV-seropositive adult B cell fraction was not suppressed even by a high dose of exogenous IFN-alpha as compared with whole mononuclear leukocytes. These data indicate that endogenous IFN suppresses the EBV-transformation not by direct anti-neoplastic activity to B cells but by augmentation of T cell and NK cell activities.