In vivo distinction between a target cell for Friend virus (FVP) and murine hematopoietic stem cells.

Busulphan (BU) treatment of DBA/2 mice with hypertransfusion (HT)-induced polycythemia resulted in an ablation of detectable hematopoietic stem cells (CFUS) in pooled marrow from the long bones. Daily injections of erythropoietin (EP) stimulated an EP-responsive population of cells in the absence of detectable CFUS. Mice treated with BU and EP and having HT-induced polycythemia were inoculated with the polycythemia-inducing strain of Friend virus (FVP) and determinations were made for the presence of tumor colony-forming units (tCFU). No change in CFUS/10(6) bone marrow cells was detected as a result of EP treatment. However, tCFU were increased more than 100-fold in HT-BU-EP-treated mice compared with saline-treated controls. The demonstration of tCFU in mice in which CFUS were not detectable indicated that this leukemogenic effect of FVP could occur in the absence of the pluripotent stem cell. Furthermore, the increased numbers of this FVP target cell in the EP-stimulated, BU-treated mice with HT-induced polycythemia supported the model licating the target for this effect in the EP-responsive cell population.