CD86 is progressively down-regulated with progression in nonlymphoid lineages and may be re-acquired by hematopoietic cells arising from transplanted CD86⁻ CD150^Hi HSCs. HSC subsets distinguishable by CD45 alleles were sorted 3 times to > 99% purity as shown in Figure 3, and 200 cells were transplanted together into lethally irradiated recipients. Six months later, donor and recipient cells of the 2 types were recovered from BM and resolved according to the differentiation scheme of Pronk et al.²⁷  Each histogram is color coded according to subset, and MFIs of CD86 staining are given. Recipient cells closely resemble those in normal mice that did not receive a transplant, and similar results were obtained with HSC subsets transplanted into separate recipients. Background staining (fluorescence minus one; FMO) is also shown in each column.