Influence of immune status of host on immunogenicity of tumors induced with two doses of methylcholanthrene.

Previous studies by Prehn demonstrated a direct correlation between the dose of carcinogen used for tumor induction and the immunogenicity of the resulting tumors. The purpose of the present study was to determine the role of the host's immune response and the influence of the carcinogen on immune function in this relationship. For that reason, a comparison was made of the immunogenicities of tumors induced with two doses of carcinogen in immunologically normal mice and in mice immunodepressed by adult thymectomy and irradiation. If the direct relationship between dose and immunogenicity demonstrated in normal mice was due to the degree of immunosuppression produced by the carcinogen, this correlation should not be apparent in mice already immunosuppressed. Although there was some increase in the immunogenicity of tumors induced in the immunosuppressed mice, the same relationship between carcinogen dose and immunogenicity was observed in both groups of mice. These results indicate that the degree of immunogenicity of tumors induced with both high and low doses of carcinogen was influenced by immunoselection, but in addition another, non-immunologic factor was significant in the relationship between carcinogen dose and immunogenicity.