title: Hematopoietic precursors in disease induced by the myeloproliferative sarcoma virus.
abstract: 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 medium conditioned by MPSV spleen cells (MPSV-CM). This factor is not MPSV and is not produced by spleen cells of noninfected mice. Two classical sources of GM-CSF, lung GM-CSF and GM-CSF contained in the plasma of endotoxin-treated mice, cannot replace the MPSV factor. Inversely, MPSV-CM does not stimulate the growth of retransplanted clusters induced in normal bone marrow with lung GM-CSF, whereas lung GM-CSF does. Two conditioned media containing activity promoting the in vitro proliferation and differentiation of hematopoietic stem cells in the mixed colony assay stimulate the growth of MPSV clusters: one medium was conditioned by pokeweed-mitogen-stimulated spleen cells, the other by the WEHI 3 cell line. The implication of the results in the comprehension of MPSV disease is discussed.
mesh_terms: D000818:Animals; D003114:Colony-Forming Units Assay; D003115:Colony-Stimulating Factors; D003470:Culture Media; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D051379:Mice; D008811:Mice, Inbred DBA; D009368:Neoplasm Transplantation; D009053:Sarcoma Viruses, Murine; D013154:Spleen / Q000166:cytology; D014412:Tumor Virus Infections / Q000473:pathology*
chemical_list: D003115:Colony-Stimulating Factors; D003470:Culture Media