SENSITIVITY OF DIFFERENT CELL LINES AND OF DIFFERENT PHASES IN CELL-CYCLE TO HYPERTHERMIA

Abstract

The sensitivity of different cell lines (Chinese hamster ovary, HeLa [human cervical cancer], L1210 and P388 [leukemia]) to 43.degree. C was compared. Chinese hamster ovary and HeLa cells were less temperature sensitive than L1210 or P388 cells. This difference persisted even when HeLa and L1210 cells were grown in the same medium and suggested that this was an inherent difference between the cell lines. Of all cell lines, 7 day L1210 ascites, maintained by transfer in mice, were the most sensitive. The greater sensitivity of these cells, as compared to 4 day L1210 ascites or cells in culture, may be explained by the difference in their growth stages. The 7 day ascites cells would be in stationary growth as compared to exponentially growing 4 day ascites or cells in culture. The temperature sensitivity of Chinese hamster ovary cells in different parts of the cell cycle was determined. Mid- and late S phase cells were more sensitive than cells in mitosis or early S; G1 and G2 cells were the least sensitive. In a partially synchronized culture, the heat sensitivity of L1210 cells increased with increased percentage of cells in the S phase.