Suppressing S1P₁ using FTY720 inhibits the mobilization of transplantable HSCs. (A) Representative scatter plots showing the contribution of donor (CD45.2), recipient (CD45.1/CD45.2), and competitor (CD45.1) cells. (B) Dot plots showing T-cell (CD3), B-cell (B220) and granulocyte (Gr-1) lineage donor (CD45.2) cells in transplantation recipients. (C) The percentage contribution to hematopoiesis in recipient mice receiving PBMCs from placebo- or FTY720-treated donors mobilized with AMD3100 is shown. The mean and standard error of 12 recipient animals is shown. (D) The percentage contribution to hematopoiesis in recipient mice receiving PB from placebo or FTY720 treated donors that were not mobilized. The mean and standard error of 6 recipient animals is shown. (E) The proportion of B cells, T cells, and granulocytes within the donor (CD45.2⁺)–derived population in primary (left panel) or secondary (right panel) recipients. All primary donors had been mobilized with AMD3100 and treated with (FTY720) or without (Control) pretreatment with FTY720. Secondary recipients received 2.5 × 10⁶ unfractionated BM from primary recipients. Data from 6 primary and 6 secondary recipients are shown for each treatment. Representative data from 1 of 2 experiments are shown.