In vitro induction of CFU-S proliferation by a non viral splenic activity from myeloproliferative sarcoma virus infected mice.
The myeloproliferative sarcoma virus (MPSV) induces a myeloproliferative syndrome in DBA/2 mice. It is characterized by a considerable increase in the number (100-fold) and in the concentration (10-fold) of pluripotent hematopoietic stem cells detected in vivo (CFU-S) in the spleens of infected animals. Prior studies have shown the presence of a mixed-colony promoting activity (MPA) in neoplastic spleens. In the presence of a small quantity of erythropoietin, MPA induces the proliferation and differentiation of pluripotent hematopoietic stem cells, detected in vitro (Mix-CFU). We tested the effect of factors produced by neoplastic spleen cells on the proliferation of day 10 CFU-S and their entry into the cell cycle. This was done by comparing the number of day 10 CFU-S present in suspensions of normal bone marrow cells incubated for 2 days on agar underlays containing cells from either normal or neoplastic spleens. Our results show the existence of an activity secreted by cells from the spleens of MPSV-infected animals which starts CFU-S cycling and which is physically distinct from MPSV. The presence of this activity, whose identity with MPA remains to be proven, would enable us to explain the proliferation of CFU-S in the course of the disease.
D000818:Animals; D002455:Cell Division; D006133:Growth Substances / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006918:Hydroxyurea / Q000494:pharmacology; D066298:In Vitro Techniques; D051379:Mice; D008811:Mice, Inbred DBA; D009053:Sarcoma Viruses, Murine; D012513:Sarcoma, Experimental / Q000473:pathology*; D013154:Spleen / Q000473:pathology*
D006133:Growth Substances; D006918:Hydroxyurea