The role of autotransplanted spleen in the erythropoietic recovery of the mouse.

Erythropoietic recovery was studied in mice subjected to subcutaneous splenic autotransplantation and compared with that observed in normal and splenectomized animals. Radioiron uptake into spleen and erythrocytes and splenic weight were measured at different times after lethal irradiation and injection of 5 x 10(5) bone marrow cells. Dose-response curves were also performed with increasing amounts of cells injected. Hematocrit recovery as a function of time after a single large dose of phenylhydrazine was also studied. Results indicate that autotransplants act qualitatively as normal spleens, but their erythropoietic capacity is diminished and the animals show an intermediate response between normal and splenectomized mice. Histological observation showed no obvious differences in morphology and spatial distribution between colonies developing in normal and transplanted spleens. It is concluded that transplants lead to normal lodgment, proliferation and erythroid differentiation of circulating stem cells. However, changes in transplant size, anatomical position and other factors such as fibrosis and blood flow may decrease their trapping area and their capacity of expansion even under conditions of high erythropoietic stimulation.