Enrichment of lineage-depleted progenitor cells. Donor C57BL6/Ly5.1 BM cells were incubated with a cocktail of antibodies to lineage-specific markers and with an antibody to Ly5.1. Aliquots of these cells were analyzed by flow cytometry before depletion of lineage-positive cells with immunomagnetic beads (A) and after the enrichment of the lineage-negative hematopoietic progenitors (B). The percentage of total cells in each quadrant is indicated.