Early time course of BM reconstitution.

Lethally irradiated Ly5.2 mice were given transplants of either 400 38⁺34⁻ cells (carrying only the Ly5.1 surface marker), 400 38⁻34⁺ cells (carrying both the Ly5.1 and the Ly5.2 surface markers) or 400 cells in a 1:1 mixture of the 2 subsets (200 cells of each). At each time point, 2 to 4 animals were killed, their BM cells extracted, and the percentages of Ly5.1 and Ly5.1-Ly5.2 cells determined. (A) Summary of the results. (B) Representative fluorescence-activated cell-sorting analysis of donor-cell BM engraftment from the 1:1 mixture at 3 time points. The data suggest that the 38⁺34⁻ subset of PHSC cannot engraft rapidly (ie, by 8 days after BMT) but can engraft by 14 days after BMT. Data are from 4 independent experiments using 2 to 4 mice per group in each experiment; the values presented are means ± SE.