Toxicity of 5-Bromo 2′-Deoxyuridine to Malignant Lymphoid Cell Lines 1

Summary Malignant lymphoid cell lines are unusually sensitive to the toxic effects of BUDR. Incubation of mouse myeloma MOPC 315 with 1 and 0.1 μg of BUDR/ml results in an acute toxic effect by Days 3 and 5, respectively. Subcultivation of MOPC 315 in 0.01 and 0.001 μg of BUDR/ml typically results in on Days 12 and 18, respectively. Similar patterns of acute toxicity occur with mouse lymphoma S49.1, human leukemia CCRF/CEM, and mouse myeloma MPC 11. The dose of BUDR required to cause a 50% inhibition of proliferation (ID50) ranges from 0.09 to 0.3 μg of BUDR/ml. In contrast, the ID50 for a variety of cell lines of alternate origins range from 3.14 μg of BUDR/ml for human cervical adenocarcinoma HeLa to 6.23 μg of BUDR/ml for mouse fibroblast L929. Fibroblasts L929 and HeLa cells were grown for 20 and 25 days, respectively, in 2 μg of BUDR/ml with no toxicity. The toxicity of 1 μg of BUDR/ml to MOPC 315 and MPC 11 is partially prevented by 1 μg of thymidine/ml and completely prevented by 10 μg of thymidine/ml. Addition of 1 μg of thy midine/ml completely protects lymphoma S49.1 from the effects of 1 μg of BUDR/ml. We wish to thank Dr. Charlotte Friend and Dr. William Scher for their helpful discussions and critical evaluation of this manuscript.