Effect of different immunization and challenge procedures on in vivo tumor immunogenicity tests

Three different methods of immunization and two methods of challenge were used to test a series of methylcholanthrene (MCA)-induced sarcomas for their immunogenicities in vivo. Although there was some variation in the degree of immunity produced, similar results were obtained with the three immunization procedures. Challenge with explants of tumor tissue was found to be as sensitive a measurement of the antitumor response as challenge with a single cell suspension. The results indicate that in a substantial series of tumors, the relative immunogenicities are characteristics of the tumors themselves and not artifacts due to the immunization or challenge procedures used.