Overexpression of

Hoxa9 in the transplantation chimeras enhances myelopoiesis and suppresses B lymphopoiesis. (A) Flow cytometric analysis of hematopoietic cells from bone marrow and spleen of representative EGFP control and Hoxa9-EGFP mice 4 weeks after transplantation. For all dot-plots analyzed, EGFP expression is shown on the x-axis and that of Mac1 or B220 on the y-axis. Hoxa9 overexpression led to a significant increase in mature GFP⁺/Mac1⁺ myeloid cells in the bone marrow (Mac1⁺ myeloid cells ranged from 53%-56% as compared with 32%-38% for control GFP mice, n = 3 per group, P = .02) and a decrease in GFP⁺/B220⁺ (range 13%-25%) forHoxa9 mice compared to GFP controls (range 24%-38%,P = .05). (B) Results shown are the means ± SD of the numbers of transduced (G418^r) and untransduced in vitro myeloid CFCs in bone marrow and spleen and of bone marrow pre-B CFCs in 4 neo and 4 Hoxa9 chimeras. (C) Analysis of the types of transduced (G418^r) myeloid CFCs present in the bone marrow of Hoxa9 and neo chimeras. Well-isolated day 12 G418^r colonies were randomly picked and examined after Wright-Giemsa staining. Results are expressed as the means ± SD of the colony types generated from bone marrow of 4Hoxa9 and 4 neo chimeras (20 colonies analyzed for each mouse). The granulocyte-erythrocyte-macrophage-megakaryocyte (GEMM) and granulocyte and granulocyte-macrophage (G/GM) colonies were significantly increased and the macrophage (M) significantly decreased in the Hoxa9 mice compared with the neocontrol mice.