Figure 2.
Hoxa-9-/- marrow cells have decreased competitive repopulating ability in vivo. Cohorts of lethally irradiated mice were injected with a fixed dose of normal competitor marrow (500 000 cells) and 1 of 3 doses of test cells (either Hoxa-9-/- vs sibling wild type or Hoxa-10-/- vs sibling wild type): 500 000 cells (1:1 ratio), 1 500 000 cells (3:1), or 4 500 000 cells (9:1). After 12 to 20 weeks, the percentage of test marrow contribution was determined by the percentage of CD45.2 cells as measured by FACS analysis of peripheral-blood lymphocytes and granulocytes. The fractional contribution of Hoxa-9-/- cells was markedly below the predicted value (horizontal black bars) at all three cell ratios tested—50%, 75%, and 90% (A), whereas the contribution of Hoxa-10-/- cells closely approximated the values for Hoxa-10+/+ cells, which were all close to the predicted values (B).