The proliferation kinetics of L 1210 ascites tumour.

The proliferation kinetics of leukemia L 1210 ascites tumour grown in DBA/2 × NMRI mice was determined. Using the host life-span method we found a tumour doubling time of 11.7 hours. The doubling time determined by cell counting was 10 hours from day 4–6, 25 hours between day 6 and 7 and about 75 hours from day 7–9 with a standard inoculum of 105 cells. Autoradiography of tumour cells after Thymidine 3H labelling on day 6 after transplantation showed a cell cycle time of 22 hours derived from the per cent labelled mitoses curve. The time spent in DNA synthesis was 15 hours. Continuous labelling showed a growth fraction very near 1. The discrepancy between our data and the data published by other authors is discussed. Neither host life-span of the mice nor cell doubling time were measurable affected with a dose of 1.0 μCi Thymidine 3H per gram of mouse used in the studies.