CD31⁺ Sca-1^– cells do not give rise to significant numbers of peripheral blood leukocytes. (A) Peripheral blood was analyzed for donor-derived (CD45.2) hematopoietic reconstitution 2 weeks following transplantation of either 10 000 CD31⁺ Lin^– c-kit⁺ Sca-1^– cells (left panel) or 250 CD31⁺ KSL cells (right panel). (B) Peripheral blood analysis at 26 weeks after irradiation. The percentage of total donor cells in the peripheral blood of a recipient representative of 3 experiments is shown.