Characteristics of in vitro colony formation by cells from haemopoietic tissues

Summary  The characteristics of stimulation of colony formationin vitro from cells of mouse haemopoietic tissues has been briefly reviewed. Mouse kidney or embryo feeder cells, media conditioned by the cells from these tissues, normal or leukemic mouse sera, sera from leukemic or infectious mononucleosis patients, human urine and mouse embryo extracts are all sources of colony stimulating activity and their properties have been described. All sources of colony-stimulating activity produce clones of cells of the granulocyte series. In tritiated thymidine treated mice injection of preparations rich in colony-stimulating activity has been shown to produce a neutrophil leucocytosis and accelerate the rate of accumulation of labelled neutrophils in the blood. It is suggested that thein vitro assay can detect factors capable of stimulating granulocyte development.