title: Demand-control of proliferative activity in the hemopoietic system of lethally irradiated mice during transfusion-induced regeneration.
abstract: The extent of cell proliferation in the hemopoietic system after bone marrow transfusion of fatally irradiated mice depends on the regeneration of proliferative capacity. This may be modified by the demand for differentiated cells in the peripheral blood. This demand was suppressed by induction of transfusion plethora prior to 800 rad whole body irradiation and bone marrow transfusion. Controls were non-plethoric recipients. For 6 days the following parameters were measured: hemopoietic proliferation by the 125-iodo-deoxyuridine (125-IUdR) incorporation technique, CFU-S content and spleen colony histology. There are three general observations from spleen and marrow with respect to 125-IUdR uptake in plethoric mice: (1) initial higher 125-IUdR uptake, (2) reduced rate of increase of 125-IUdR incorporation, (3) this rate of increasing 125-IUdR uptake in spleen was more depressed than in marrow. On day 6 cellularity and CFU-S in spleen was below, and in marrow above that of the control. These data suggest that initially after fatal irradiation of control mice differentiation of transfused CFU-S predominates over proliferation. Later as the mice become anemic and erythropoietin is produced the stimulation to proliferate is greater in the control than in the plethoric mice in which erythrocytic proliferation is suppressed. These data suggest that there are multiple feedback loops that regulate regeneration in the spleen and the bone marrow. These differences may be connected with the microenvironment that preferentially initiates erythropoiesis in the spleen before the marrow and granulopoiesis in the marrow before the spleen.
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000502:physiology / Q000528:radiation effects*; D016026:Bone Marrow Transplantation; D002478:Cells, Cultured; D005260:Female; D006412:Hematopoietic Stem Cells / Q000502:physiology / Q000528:radiation effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D012038:Regeneration / Q000528:radiation effects*; D013154:Spleen / Q000502:physiology / Q000528:radiation effects; D014916:Whole-Body Irradiation