Variations in the response of cloned murine friend erythroleukemia cells to different inducers.

Cells of the line 3BM-78 derived from murine bone marrow cells infected in vitro with polycythemic Friend leukemia virus (FLV-P) produce virus with spleen focus-forming activity (SFFV) and can be induced to synthesize hemoglobin. Fifteen clones, isolated from this line, have been analyzed in detail for the effect of different inducing agents (dimethyl-sulfoxide, DMSO; hexamethylene bisacetamide, HMBA; and sodium butyrate, SB) on the synthesis of hemoglobin and virus at the clonal level. All the clones proved to be inducible with one or more of the agents, but the degree of the response depended on the type and concentration of the agent used. In general, the effectiveness of the agent--within the usual range of concentration for induction--both for hemoglobin and for virus synthesis, was in the order HMBA greater than DMSO greater than SB. Reverse transcriptase activity was, however, more easily induced than hemoglobin synthesis in that stimulation was seen at lower concentrations of the same inducing agent. This clonal analysis confirmed that virus and hemoglobin production are regulated independently in these erythroleukemic cells chronically infected with FLV-P.