Tumor resistance induced by syngeneic bone marrow transplantation and enhanced by interleukin 2: a model for the graft versus leukemia reaction.

Lethally irradiated C3H/HeN mice reconstituted with normal syngeneic bone marrow survived significantly longer than unmanipulated control mice following challenge with a lethal dose of 38C13 lymphoma cells 2 to 3 weeks post-bone marrow transplantation (BMT). Although the magnitude of this effect was modest, it was highly reproducible. This resistance-producing effect of BMT could be enhanced by interleukin 2 administration and could be abrogated by anti-asialo-GM1 antiserum treatment of recipients. These findings are consistent with the hypothesis that cells with a natural killer phenotype are activated by BMT and can mediate tumor resistance. These studies provide a model to explore the cellular basis, independent of donor alloreactivity, of the graft antitumor effect of BMT observed in humans.