Comparison of the Sensitivity of Normal Hematopoietic and Transplanted Lymphoma Colony-Forming Cells of Mice to Vinblastine Administered In Vivo2

Abstract

Dose-response curves were determined for hematopoietic and lymphoma colony-forming cells in the femoral marrows and spleens of mice after exposure for 24 hours to vinblastine. The hematopoietic colony-forming cells decreased to 19 and 1 percent of the control values in the marrow and spleen, respectively, at the highest dose used (1 mg/mouse). With the same dose, the lymphoma colony-forming cells decreased to 0.08 and 0.002 percent of the control values in the marrow and spleen, respectively. The difference in the sensitivity of the normal and lymphoma colony-forming cells to vinblastine was thus similar to the difference in sensitivity to tritiated thymidine seen previously. Both differences could bed result of the relative numbers of these two types of cells passing through cell cycle in a 24-hour period. Studies with combined vinblastine and tritiated thymidine treatment support this view. Combined treatment with the two agents produced no greater effect than when either agent was given separately. Since both agents have been shown to kill cells in cell cycle, presumably the surviving cells are not in rapid cell cycle.