Thymus-conditioned medium influences in vitro colony formation by hematopoietic progenitor cells.
Medium conditioned by mouse thymic cells cultured for 7 days in the presence of concanavalin A (Con A) and 5% human serum enhanced erythroid colony formation by CFU-E but not BFU-E. Medium conditioned by thymic cells for less than 7 days or more than 7 days inhibited erythroid colony formation. Enhancement of erythroid colony formation occurred at both suboptimal and saturating concentrations of erythropoietin. The thymus-conditioned medium also stimulated the growth of granulocyte/macrophage colonies by itself and in the presence of a saturating concentration of WEHI-3 conditioned medium. The conditioned medium contained neither burst-promoting activity nor erythropoietin. The erythroid colony-enhancing activity in the thymus-conditioned medium was heat stable, bound to immobilized Con A, lacked protease activity and migrated with an approximate molecular weight of 68,000 on gel filtration.
D000818:Animals; D003114:Colony-Forming Units Assay; D003208:Concanavalin A / Q000494:pharmacology; D003470:Culture Media; D004920:Erythropoiesis; D004921:Erythropoietin / Q000494:pharmacology; D005260:Female; D006098:Granulocytes / Q000166:cytology; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006358:Hot Temperature; D008264:Macrophages / Q000166:cytology; D051379:Mice; D008970:Molecular Weight; D013601:T-Lymphocytes / Q000502:physiology*
D003470:Culture Media; D003208:Concanavalin A; D004921:Erythropoietin