Defects in T cells and granulocytes are cell autonomous. (A) Top panels show contribution of donor FL cells (Ly5.2⁺) and competitor BM (Ly5.1⁺) to peripheral blood 4 months after transplantation. The contribution of FL donor cells (R1 gate) to granulocytes (Gr-1⁺ and Mac-1⁺), B (B220⁺) and T (Thy1.2⁺) lymphocytes, and CD4⁺ and CD8⁺ T cells is shown in panels below. The R2 and R3 gates surround Gr-1^hiMac-1^lo and Gr-1^hiMac-1^hi populations, respectively. Cells in the R4 gate are FL-derived Thy1.2⁺ T cells, which are absent in mice reconstituted with Cbfb^rss/−; cells. Equivalent contribution to B220⁺ B cells is seen with all 3 Cbfb genotypes. n_+/+ = 9, n_rss/rss = 9, and n_rss/− = 11; shown are representative recipients. (B) Relative contribution of Cbfb^+/+, Cbfb^rss/rss, and Cbfb^rss/−; FL cells versus BM competitor cells to the KSL population in the BM of recipient mice, analyzed 12 months after transplantation. A mixture of Ly5.1⁺ and Ly5.2⁺ BM is shown as a control. Cells in gated regions (R1, R2) are analyzed in the plots below. Note the overwhelming contribution of FL cells (Ly5.2⁺) from all 3 Cbfb genotypes to the KSL population. (C) Percentage of c-Kit⁺Sca-1⁺Lin⁻ (KSL) donor-derived progenitors in bone marrow of mice that received a transplant of Cbfb^+/+, Cbfb^rss/rss, or Cbfb^rss/−; FL cells. (D) Contribution of FL donor and BM competitor cells to Gr-1⁺Mac-1⁺ BM cells. (E) Contribution of Cbfb^+/+, Cbfb^rss/rss, and Cbfb^rss/−; FL cells to CD4⁺CD8⁺ cells in the thymus of transplant recipients. Note that although the KSL and Gr-1⁺Mac-1⁺ populations in mice reconstituted with Cbfb^rss/−; FL cells are predominantly donor derived (B,D), CD4⁺CD8⁺ cells are derived almost entirely from the competitor BM.