Conditioning of donor BM by host tumor. Lethally irradiated 22-week-old BALB-neuT females received transplants of BM from CB6F1 mice. (A) Kinetics of BM uptake, tumor development, and myeloid expansion in the PB of 3 representative mice that had received transplants. (B) CFU assay with spleen cells of 33-week-old BALB-neuT mice that had received transplants (10 to 11 weeks after the transplantation) and of CB6F1 control mice. (C) Proliferation of total splenocytes from BALB-neuT mice with transplants in response to alloantigens in mixed leukocyte reaction (□), increased upon removal of Gr-1⁺/Mac-1⁺ cells (▪); alloproliferation of normal donor CB6F1 splenocytes declined upon addition of 10% of Gr-1⁺/Mac-1⁺ cells (▧) from BALB-neuT mice receiving transplants. Results are from 3 of 10 mice tested. Mean of 3 replicates ± SD.