Sensitivity of L Cells in Exponential and Stationary Phase to 5-Fluorouracil

Abstract

ANTICANCER agents have recently been classified according to their lethal effects on normal murine haematopoietic and lymphoma spleen colony-forming cells¹. The members of one class, which includes 5-fluorouracil, reduce the survival in vivo of actively dividing lymphoma cells by a far greater degree than that of normal haematopoietic cells which are presumed to be in a resting state. When these two cell types were treated with 5-fluorouracil in vitro and assayed in vivo, a similar difference in survival was noted². It was proposed that this difference in sensitivity is a consequence of the difference between the proliferative states of the two cell types^1,2. In order to test this hypothesis and to establish a model system in vitro, the sensitivity of mouse L cells to 5-fluorouracil was determined by the colony formation method of Puck et al.³, either when the cells were in a rapidly proliferating state (exponential phase) or when they were in a non-proliferating state (stationary phase). Few reports of the survival of the colony forming ability of mammalian cells in vitro following exposure to chemotherapeutic agents have been published and in only one instance has the lethal effect of 5-fluorouracil been described in such a system⁴.