Sensitivity to bleomycin of JTC-11 cells modified by serum concentration and underlaid 3T3 cells

The sensitivity to bleomycin of JTC-11 cells derived from Ehrlich ascites tumor was modified by both serum concentration and superinoculation on a sheet of Swiss 3T3 cells. The dose-survival curve of the JTC-11 cells was biphasic or triphasic, with a sensitive phase at lower doses (less than 10 micrograms/ml) and a resistant one at higher doses (more than 40 micrograms/ml). Sensitivity of JTC-11 cells to bleomycin decreased with increases in the serum concentration. When JTC-11 cells were superinoculated on the sheet of Swiss 3T3 cells, the sensitivity of JTC-11 cells to bleomycin did not change with increases in the serum concentrations.