Moloney murine sarcoma virus oncogenesis in T-lymphocyte-deprived mice: Biologic and immunologic studies

CBA mice, selectively deprived of T-lymphocytes by adult thymectomy, X-irradiation, and syngeneic bone marrow injection, have a high susceptibility to Moloney murine sarcoma virus (M-MuSV) oncogenesis. These mice developed nonregressing tumors after they had received injections of the virus either im or intradermally (Id) and in various concentrations. The time to tumor induction was inversely proportional to the amount of virus injected. After iv inoculation of the virus, deprived mice usually developed sarcomas in various soft tissues of the body. The importance of the T-cells in affording protection was further confirmed by the observation that lymph node cells depleted of T-cells were unable to prevent tumor development in the deprived inoculated mice. A protective effect of T-cells could be provided by transfer of as few as 0.25 x 10 ⁶ lymphoid cells. The effect was long-lasting because comparable results were obtained when deprived mice were given injections of graded numbers of cells immediately or 60 days before M-MuSV inoculation. When spleen cells from M-MuSV immune donors (i.e., deprived mice protected with lymph node cells before M-MuSV inoculation) were transferred into deprived mice 10 days before the M-MuSV injection, the protective effect depended on the presence of T-cells within the cell inoculum; B-cells apparently were unable to prevent tumor development. In addition, when normal and deprived mice were given id injections of M-MuSV and their tumors were excised, normal mice were resistant to a second M-MuSV challenge, whereas deprived mice developed tumors. Tumor-bearing deprived mice could be cured by transfer of immune lymph node cells from M-MuSV tumor regressor mice.