Relationship of Success in Classical Immunotherapy to the Relative Immunorejective Strength of the Tumor<xref ref-type="fn" rid="FN2">2</xref>

Abstract

Six tumors of varying immunorejective strengths were used to compare the response of their isogenic hosts to standardized regimens of immunoprophylaxis and immunotherapy. The tumors were generated spontaneously or induced chemically [with 9,10-dimethyl-1,2-benzanthracene (CAS: 57-97-6)], virally (with murine leukemia virus), or radiogenically (with strontium-90). The hosts were C57BL/6J or BALB/cByJ mice. Immunoprophylaxis and immunotherapy were performed with isogenic irradiated tumor cells, with Corynebacterium parvum, or with both. The results of challenge experiments were quantified as the doses of viable tumor cells that produced 50% tumor deaths for immunized and for control mice. The results for these quantitative "classical" immunoprophylaxis and immunotherapy experiments were consistent with two theses: that only immunorejective tumors give positive results with classical immunotherapy and that classical immunoprophylaxis is more effective than classical immunotherapy when identical materials are used for immunizations. These results have important consequences for the clinical use of classical immunotherapy.