title: Production of stem cell proliferation stimulators and inhibitors by haemopoietic cell suspensions.
abstract: In mice treated with phenylhydrazine haemopoietic spleen colony forming cells (CFU-S) are proliferating rapidly in the bone marrow but not in the spleen. Using such mice we have investigated the production of factors responsible for the control of CFU-S proliferation. When irradiated spleen cells are incubated with non-irradiated bone marrow cells there is a marked fall in the proportion of femoral CFU-S in DNA synthesis. In the converse experiments, rapid triggering of splenic CFU-S is achieved. Both these effects can be eliminated by washing the irradiated cells prior to incubation; they are, however, retained in the supernatant media "conditioned" by these cells. When the washed cells are incubated in fresh medium at 37 degrees C both stimulatory and inhibitory activities reappear but after different incubation periods. The data demonstrate that both proliferation stimulatory and inhibitory factors acting on CFU-S can be produced by the same haemopoietic cell suspension.
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000187:drug effects / Q000502:physiology; D001854:Bone Marrow Cells; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D003114:Colony-Forming Units Assay; D003115:Colony-Stimulating Factors / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D010659:Phenylhydrazines / Q000494:pharmacology; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors
chemical_list: D003115:Colony-Stimulating Factors; D010659:Phenylhydrazines