Absence of leukemic organ infiltration or GVHD in mixed chimeras receiving DLI and EL4.

Histologic analysis of mixed chimeras and full chimeras receiving DLI and EL4 was performed on animals that had succumbed to EL4 leukemia or on animals killed at the end of the observation period. On necropsy, overt infiltration of liver and kidney by leukemic cells was evident in full chimeras receiving DLI and EL4. In contrast, mixed chimeras receiving DLI and EL4 were killed on day 169 after BMT and showed no tumor cell infiltration. Histologic sections from 2 representative chimeras are presented. Liver and kidney from a full chimera receiving DLI and EL4 showed severe infiltration with leukemic cells. In contrast, mixed chimeras receiving DLI showed normal tissue morphology.