Treatment of a fatal transplantable erythroleukemia by procedures that lower endogenous erythropoietin.

The in vitro growth of primary erythroleukemia cells has been examined in the presence and absence of the hormone erythropoietin (EPO). Although these leukemic cells had previously been considered to be hormone-independent, addition of EPO was found to be essential for maximum growth in culture. Erythroid colonies that grew in the presence of EPO were leukemogenic when returned to mice. Influence of EPO on the in vivo growth of leukemic cells was indicated by our findings that administration of the hormone caused a more severe leukemia and rapid death, and transfusion of red blood cells, which lowers endogenous EPO, led to decreased spleen size and increased survival of leukemic mice. We suggest from our results that hormone-associated therapy might be efficacious in the treatment of this and, perhaps, other leukemias.