The mechanism of action of macrophage colony-stimulating factor (M-CSF) in osteoclast development was examined in a co-culture system of mouse osteoblastic cells and spleen cells. In this co-culture, osteoclast-like multinucleated cells (MNCs) were formed within 6 d in response to 10 nM 1 alpha,25(OH)2D3 added only for the final 2 d of culture. Simultaneously adding hydroxyurea for the final 2 ...

The radioprotective agent WR-2721 was examined for its effects on modifying the cytotoxicity of HN2 against normal and tumor cells in the AKR mouse. Quantitation was carried out by the spleen colony assay for both normal hematopoietic stem cells and AKR leukemia cells. Protection from drug toxicity and normal cell cytotoxicity was noted. Potentiation of cytotoxicity to AKR leukemia was found.

Granulocyte and macrophage precursors (GM-CFU-C-), which differentiate in vitro without added granulocyte and macrophage colony stimulating factor (GM-CSF), can be detected in the hematopoietic organs of mice infected with myeloproliferative sarcoma virus (MPSV). Retransplantation experiments have shown that the GM-CFU-C- are incapable of autonomous growth and depend on a factor present in medi...

In this study, we examined the consequences of Fas deficiency on hematopoiesis in C57BL/6-lpr/lpr mice. We found a striking extramedullary increase in hematopoietic progenitor cells, comprising erythroid and nonerythroid lineages alike. These modifications preceded the lymphadenopathy, because early progenitors (colony-forming units-spleen [CFUS] day 8) were already augmented in day-18 fetal li...

The consequences of long-term in vivo expression of human c-mpl ligand in a mouse model were examined. Transgenic mice expressing the human full-length cDNA in the liver exhibited a fourfold increase in circulating platelet count that persisted stably over the life of the animals. Transgenic animals thrived and appeared healthy for at least 500 days. Transgenic platelets appeared normal with re...

Hemopoietic stem cells as defined by the capacity to produce spleen colonies in lethally irradiated recipients were reported by P. F. Bartlett [(1982) Proc. Natl. Acad. Sci. USA 79, 2722-2725] to be present in high frequencies in mouse brain. He also reported similar numbers of colony-forming units, spleen (CFU-s), in the brains of Wf/Wf mice, the bone marrow of which lacks detectable spleen co...

Cells that generate splenic colonies within 8 days (day-8 colony-forming units-spleen [CFU-s]) are generally thought to differentiate only into erythroid/myeloid cells. The T and B lymphocyte differentiation potentials of day-8 CFU-s were evaluated and compared with those of day-12 and 5-fluorouracil (5-FU) CFU-s. This was achieved by analyzing, after intravenous and intrathymic injection, the ...

Stem cell factor (SCF) is the ligand for the receptor encoded by the c-kit proto-oncogene. Mutations of either c-kit or the SCF gene are responsible for the defects of W and SI mutant mice, which both suffer a macrocytic anemia, the former associated with defective stem cells and the latter with a defective hematopoietic microenvironment. PEGylated recombinant rat SCF was administered to normal...