Increased Growth of Tumor Isotransplants After Immunosuppression of the Recipient Mice by Methotrexate or 5-Fluoro-2′-Deoxyuridine

Summary

Immunosuppression of a graft recipient by chemotherapy or irradiation delays rejection of homotransplants in animals and man. If such immunosuppression were shown to similarly influence the growth of syngeneic tumors (isctransplants), it would provide another kind of evidence that tumor tissue is antigenically different from normal host tissues and that host immunologic mechanisms react against these antigenic differences to inhibit tumor growth. This concept was tested by quantitative transplantation of syngeneic tumors in immunosuppressed mice. Fibrosarcomas were induced in C57BL/6 mice by a single intramuscular injection of methylcholanthrene. Primary syngeneic transplants, with the use of cell suspensions, were made into mice given Methotrexate (MTX) or 5-fluoro-2′-deoxyuridine (FUDR) and into normal recipients. Various forms of treatment of the recipients with MTX or FUDR resulted in a higher percentage of takes than occurred in untreated control recipients.