Kinetics of pluripotent hemopoietic precursors in vitro after erythropoietic stimulation or suppression.

The kinetics of pluripotent hemopoietic precursors (CFUmix) in vitro was studied during erythropoietic stimulation and suppression. Erythropoiesis was stimulated by the subcutaneous injection of 60 mg per kg phenylhydrazine hydrochloride on days 0, 1 and 3. Erythropoiesis was suppressed by transfusion of 1 ml of the packed red cells on three consecutive days. After erythropoietic stimulation, CFUmix were decreased in the femur and increased in the spleen. In contrast, the CFUmix were increased in both the femur and the spleen after suppression of erythropoiesis. The kinetic behavior of CFUmix were similar to those of CFUS reported previously. The behavior of CFUmix during erythropoietic stimulation and suppression revealed another biologic similarity between CFUmix and CFUS, in addition to the similarity of proliferative state and sedimentation velocity.