A RAPID FATAL ERYTHROLEUKEMIA CAUSED BY J2E CELLS CAN BE TREATED EX-VIVO WITH ERYTHROPOIETIN

The J2E cell line is an immature erythroid line which terminally diffe rentiates in response to erythropoietin (epo), producing mature, hemog lobin-synthesizing red blood cells. We have shown that when these cell s were injected into mice a rapid and fatal erythroleukemia developed with symptoms of severe anemia and hepatosplenomegaly. Southern blotti ng demonstrated that the leukemic cells were the introduced J2E cells. In addition to spleen and liver, the bone marrow was a major site of leukemic cell infiltration, and when grown in vitro leukemic cells fro m bone marrow remained responsive to erythropoietin. We reasoned, ther efore, that treatment of mice with this hormone should alleviate the e rythroleukemia, but regular injections of epo in vivo failed to arrest the progress of the disease. However, when bone marrow from leukemic mice was exposed continuously to the hormone ex vivo, before reinfusio n into naive recipients, a marked extension in life span was observed. It was concluded that ex vivo epo treatment could be used therapeutic ally for J2E cell erythroleukemias.