Genetic analysis of in vitro leukemogenesis induced by thymus epithelial reticulum cells transmitting murine leukemia viruses

Lymphoma development from transplanted murine leukemia virus infected organ cultured thymuses: inhibitory effect of in vitro interferon treatment

Thymuses of 14-day-old AKR mouse embryos were infected with Gross murine leukemia virus (MuLV) and then maintained in organ culture for 3 weeks. When they were transplanted to 3-week-old (AKR X C3H)F1 mice, approximately 50% of these developed T lymphomas within 3-4 months. Most (22/23) tumors were of host, F1-hybrid, origin while only one was of donor AKR type. No clear evidence for in vitro MuLV-induced lymphoma cells was therefore obtained. Exposure of MuLV-infected embryonic thymuses to interferon during the organ culture period significantly reduced the incidence of lymphomas in mice receiving such thymus transpalnts. Interferon also prevented the appearance of detectable numbers of MuLV antigen-containing lymphocytes in infected organ-cultured thymuses. In contrast, despite the use of very high interferon concentrations, no effects were seen on the number of viable thymic lymphocytes, their proliferation or responsiveness to the polyclonal T-cell mitogens concanavalin A (Con A) and leukoagglutinin (LA). Thus interferon, presumably through an antiviral effect, can limit the MuLV infection in the thymus and its consequence, i.e. development of a lymphoma.