Tumor Promotion by 1-Fluoro-2,4-dinitrobenzene, a Potent Skin Sensitizer¹

1-Fluoro-2,4-dinitrobenzene (DNFB) is a potent tumorpromoting agent. After topical application with 125 μg of 7,12-dimethylbenz[α]anthracene followed by 5 paintings a week with 0.1% DNFB in acetone, mice developed tumors in as short a time as 4 weeks. After 38 weeks, about two-thirds of the animals had tumors. Treatment with DNFB alone does not produce tumors, nor is the lysine conjugate of DNFB a tumor promoter. These results suggest a relationship between tumor promotion and disturbance of the immune system in sensitive animals.