Studies of nitrogen mustard transport by mouse myeloma and hemopoietic precursor cells.

We studied the transport of nitrogen mustard (HN2) by mouse hemopoietic and transplantable myeloma (Adj. PC-5 and MOPC 460D) stem cells, using gradients of tempera ture and choline chloride. Bone marrow and myeloma cells were exposed to HN2 in culture at various temperatures, washed, and tested for colony-forming efficiency. The protective effect of lowered temperatures was similar for normal marrow colony-forming units and both lines of myeloma cells. When cells were exposed to HN2 in the presence of choline chloride, the survival of colony-forming units increased, and the dose response curves were similar among the three classes of cells. We were unable to demonstrate a qualitative difference in the transport of HN2 by mouse hemopoietic precursor cells and the stem cells of two myelomas with different sensitivities to HN2.