Carcinogen-induced immune depression: absence in mice resistant to chemical oncogenesis.

Administration of 3-methylcholanthrene 6 days before antigenic challenge depressed the immune response to sheep red cells in young adult mice (C3Hf/Bi strain) sensitive to the oncogenic effect of the drug (100 percent local tumors 240 days after carcinogen). The drug was not immunodepressant in the I strain, which is relatively resistant to its carcinogenic effect (11 percent local tumors 240 days after carcinogen).