Lymphopenic phenotype in OcnCre;iDTR mice was not caused by a stem cell defect. (A) 44,000 flow sorted Ly6D⁻ or Ly6D⁺ CLPs from SJL (CD45.1) mice were intravenously transplanted into each of 10 nonirradiated C57BL/6J (CD45.2) recipients. Recipients were bled 3 wk after transplant for enumeration of donor-derived B and T reconstitution by staining with CD45.1, B220, CD4 and CD8 antibodies and analysis by flow cytometry. Experiment was performed twice independently; n = 10/experiment. Data show mean ± SEM. (B) Mature osteolineage cells were deleted from OcnCre;iDTR mice and hematopoietic stem cells (LKS SLAM), Lineage^Loc-Kit⁺Sca⁺ (LKS) multipotent progenitors, and Lineage^Loc-Kit⁺Sca⁻ cells were enumerated by flow cytometry. (C) Cell cycle analysis of the indicated cell populations was performed by flow cytometry. (D) Frequency of apoptotic (AnnexinV⁺7-AAD⁻) and necrotic (AnnexinV⁺7-AAD⁺) LKS SLAM, LKS, and Lineage^Loc-Kit⁺Sca⁻ cells was assessed. Experiments were repeated 3 times independently; n = 5–16 mice/group. Data show mean ± SEM. (E) CD45.2 OcnCre;iDTR mutant or control donor cells were mixed with CD45.1 SJL donor cells in a 1:1 ratio, injected into primary SJL recipients. Reconstitution was assessed at 8, 12, and 16 wk after transplantation. Bone marrow cells from primary recipients were harvested and transplanted into secondary recipients. Reconstitution was assessed at 8, 12, and 16 wk following transplantation. Transplantation was performed twice independently; n = 20–22 mice/experiment. Data show mean ± SEM.