Prolonged immunosuppression and tumor induction by a chemical carcinogen injected at birth.

The injection of 60 micrograms of 9,10-dimethyl-1,2-benzanthracene into newborn mice gave rise to a very high incidence of malignant thymomas. The tumor incidence was directly related to the dose of the carcinogen. The neonatal injection of the carcinogen also resulted in a depression in the immune response when the animals were challenged with an antigert as early as 4 weeks or as late as 11 weeks after administration of the carcinogen.