Figure 1. Experimental design and establishment of a chimera chronic leukemia chimeric model.

A) Overview of the experimental design for generation of CML chimeras, 2×10⁶ whole bone marrow (WBM) cells from either C57BL/6 mice (CD45.2; Control) or Scl-tTa-BCR-ABL (CD45.2; Transgenic) mice mixed with 2×10⁶ C57BL/6 congenic for the CD45 locus (CD45.1; Normal) and transplanted into mice on tetracycline. Chimerism was established for 16 weeks before tetracycline withdrawal and induction of BCR-ABL in those cells carrying the two transgenes. Tissues cells were obtained 4 weeks after induction and CD45.1⁺ cells from control transplants; leukemic-exposed (CD45.1⁺ cells from leukemic mice), or leukemic cells (CD45.2⁺ transgenic cells from leukemic mice) were analyzed.

(B) Survival curves of control and transgenic chimeric mice after Tet withdrawal.

(C) The CD45.1 chimerism results are based on staining of lymphoid (B220/CD3) and myeloid (Mac1/Gr1) cells in peripheral blood versus CD45.2 (control or leukemic) over time, n=4 per time point. Error bars represent ± SEM.

(D) Representative FACS profiles from 4 experiments characterizing the peripheral blood of control or leukemic mice showing the chimerism of CD45.1 versus CD45.2 from control or transgenic chimeric mice 4 weeks after Tet removal [Upper Panel]. FACS profiles of CD45.1 cells in the peripheral blood of control or leukemic mice at 4 weeks post Tet removal. Cells were stained for B220/CD3 and B220/Mac1-Gr1. Cells that stain positive for both fluorochromes are B lineages (B220⁺), while those that stain only for B220/CD4 and CD8 are T lineage cells (CD4/8), and those cells that are positive for only B220/Mac1-Gr1 are of the myeloid lineage (Mac1-Gr1) [Lower Panel].

(E) Representative FACS profiles from the bone marrow gating for CD45.1⁺ B lineage cells (B220⁺ CD43^+/−) of either control or transgenic chimeric mice at 4 weeks post Tet withdrawal. Dot plots from leukemic cells (CD45.2) from the transgenic chimeric mice are shown for comparison [right]. Similarly, bone marrow and spleens from control and transgenic chimeric mice were analyzed for the CD45.1⁺ myeloid lineage cells (Mac1⁺ and Gr1⁺) and leukemic cells (CD45.2⁺) are shown for comparison, n=5. See also Figure S1.