Figure 1.
Limiting dilution analysis based on competitive repopulation. Varying numbers of bone marrow cells from either 2- or 18-mo-old mice were mixed with 2 × 105 bone marrow cells from 2-mo-old mice and injected into lethally irradiated mice. Reconstitution in myeloid and B and T lymphoid lineages was evaluated 12 wk after transplantation. Mice were considered to be negative when percent chimerism for myeloid or B or T lymphoid lineage was <1.0. 1 in 3.2 × 104 cells and 1 in 1.6 × 104 cells was a multilineage repopulating cell for 2-mo-old (▪) and 18-mo-old (•) mice. When uni- and bilineage repopulating cells were included in estimations of frequencies, 1 in 1.0 × 104 cells was a repopulating cell in 18-mo-old mice (○).