Target cell of the polycythemia-inducing Friend virus: studies with myleran.

A single injection of Myleran reduced the pluripotent hematopoietic stem cell, i.e., colony forming unit(s) (CFU), and the erythropoietin-responsive cell (ERC) in polycythemic mice to around 0.5% that of the controls. Repeated injections of erythropoietin (EP) restored ERC populations, whereas the CFU remained at very low levels. This selective action of Myleran and EP in polycythemic mice seemed to be a good approach for the study of oncogenic action of Friend virus on target cells. When the CFU and ERC compartments were decreased, practically no response to the virus was obtained. When there was an appreciable ERC population present with decreased CFU, leukemogenesis still occurred (as judged by the increased spleen weight). This result was in proportion to the dose of EP, i.e., stimulation of the ERC or closely related cells.