Reduction in Cxcr4¹⁰¹³-bearing early B and T cell progenitors involves cell-intrinsic defects. (A) Absolute numbers of naive (CD44^−/lowCD62L^high) CD3⁺ T cells and immature (Immat.; B220⁺IgM^highCD21^low) B cells were determined by flow cytometry from blood samples of WT, Cxcr4^+/1013 (+/1013), and Cxcr4^1013/1013 (1013/1013) mice. Data are from three independent experiments with five to nine mice per group. (B) Absolute numbers of pro–B cells (B220⁺IgM⁻CD43⁺) and pre–B cells (B220⁺IgM⁻CD43⁻) were determined from two femurs. Data are from four independent experiments with seven mice per group. (C) Caspase-3 cleavage was used to detect the percentages of apoptotic BM pro– and pre–B cells. Data are from two independent experiments with six mice per group. (D and E) Total thymi were analyzed for numbers of DN stage 1 (DN1; CD4⁻CD8⁻CD44⁺CD25⁻), DN2 (CD44⁺CD25⁺), DN3 (CD44⁻CD25⁺), and DN4 (CD44⁻CD25⁻) cells (D) and for numbers of ETP (Lin⁻CD4⁻CD8⁻c-Kit⁺CD44^highCD25⁻) cells (E). Data are from four independent experiments with seven mice per group. (F) Absolute numbers of myeloid cells (Gr1⁺CD11b⁺) were determined from blood and BM samples of WT and mutant mice. Data are from three independent experiments with five to seven mice per group. (G) Schematic diagram for the generation of long-term BM chimeras. (H) Absolute numbers of donor CD45.2⁺ (WT, +/1013, or 1013/1013) total CD3⁺ T and B220⁺ B cells, pro–B cells, and ETPs recovered from the blood, BM, and thymus of BM chimeras in CD45.1⁺ (WT) recipients. Data are from at least three independent experiments with 6–12 recipient mice per group. (I) Absolute numbers of donor CD45.2⁺ myeloid cells recovered from the blood and BM of BM chimeras in CD45.1⁺ recipients. Data are from at least three independent experiments with 6–12 recipient mice per group. All displayed results are represented as means ± SEM. Kruskal–Wallis H test–associated p-values (#) are indicated. *, P < 0.05; **, P < 0.005; and ***, P < 0.0005 compared with WT or CD45.2⁺ donor WT cells; ^§, P < 0.05; and ^§§, P < 0.005 compared with +/1013 or CD45.2⁺ donor +/1013 cells (as determined using the two-tailed Student’s t test).