Myeloid progenitor potential of human peripheral blood cells. (A) Peripheral blood mononuclear cells (PBMCs) were analyzed in the context of CD11b and CD14 and sorted into 4 distinct populations (FACS plot are shown for 1 patient). Sorted cells were then cultured in the presence of MCSF and RANKL for 2 weeks, stained for TRAcP, and photographed at ×10 magnification (2 representative patients shown). (B) Equal numbers (10 K) from each population were cultured in the presence of MCSF and RANKL and TRAcP⁺ osteoclasts with 3 or more nuclei and mononuclear cells (MNCs) were counted. (C) Equal numbers of cells from each population plated into methylcellulose and scored at day 10 for BFU-E, CFU-E, CFU-GM, and CFU-GEM. (D) The DN population was dissected further by sorting CD115⁻ and CD115⁺ cells within the DN gate (2 representative patients shown). 10 K of sorted cells were grown in osteoclastic conditions and stained for TRAcP (photographed at ×35 magnification). (E) Higher magnification shows examples of multinucleated osteoclasts which were enumerated in (F) as well as TRAcP⁺ MNCs. (G) Equal numbers of sorted cells were grown in myeloid-erythroid methylcellulose for 10 days and then colonies enumerated. BFU-E, burst-forming unit-erythroid; CFU- colony forming unit; E, erythrocyte; G, granulocyte; GEM, granulocyte, erythrocyte, and monocyte; GM, granulocyte and monocyte; M, monocyte.