Table 1.
HSCs are enriched within the CD48- fraction but not the CD48+ fraction of old bone marrow, reconstituted bone marrow, and cyclophosphamide/G-CSF-mobilized spleen
| Source of cells | No. donor-type cells transplanted | No. mice with long-term multilineage engraftment/no. mice total |
|---|---|---|
| Old bone marrow | ||
| CD48+ | 60 000 | 1/11 |
| CD48– | 140 000 | 11/11 |
| Mobilized splenocytes | ||
| CD48+ | 30 000 | 0/5 |
| CD48– | 170 000 | 5/5 |
| Reconstituted bone marrow | ||
| CD48+ | 35 000 | 0/5 |
| CD48– | 165 000 | 4/7 |
Old bone marrow cells were obtained from 26- to 28-month-old C57BL mice. Mobilized splenocytes were obtained from mice that had been treated with cyclophosphamide followed by 7 daily injections of G-CSF.13 Reconstituted bone marrow cells were obtained from mice that had been long-term multilineage reconstituted for 20 to 24 weeks by highly enriched HSCs. Donor cells from reconstituted mice were selected for donor cell origin (CD45.1+) in addition to CD48. The indicated number of donor-type (CD45.1+) cells was transplanted intravenously into lethally irradiated recipients (CD45.2+) along with 200 000 recipient-type (CD45.2+) whole bone marrow cells. The dose of CD48+ or CD48– donor cells was based on the number of cells from each population contained in 200 000 old bone marrow, mobilized spleen, or reconstituted bone marrow cells as done in previous studies of marker expression on HSCs.3,10,13,19 Mice were considered long-term multilineage reconstituted if donor-type myeloid, B, and T cells were present for at least 16 weeks after transplantation.