Absence of IFN-γ signaling on donor marrow, but not the DLI, leads to enhanced tumor protection, even in the absence of the thymus. (A) All groups were thymectomized and received allogeneic bone marrow but received either an alloreactive or host-tolerized DLI of 20 × 106 cells on days 14 and 28 that could or could not signal through IFN-γ. All groups were then challenged on day 42 with MB49 tumor, 7 mice/group, *P < .05. Survival differences were not significant (P = .33). (B) Thymus-bearing allogeneic BMT recipients were infused with wild-type or IFN-γR1−/− allogeneic bone marrow and given a normal alloreactive DLI of 20 × 106 cells on days 14 and 28. All groups were then challenged on day 42 with MB49 tumor, 5 mice/group, *P < .05. (C) Thymectomized allogeneic BMT recipients were infused with wild-type or IFN-γR1−/− bone marrow and given a normal alloreactive DLI of 20 × 106 cells on days 14 and 28. All groups were then challenged on day 42 with MB49 tumor, 10 mice/group. *P < .05.
