Studies on Induced Resistance against Isotransplants of Virus-induced Leukemia.

The antigenicity of several well established Moloney virus-induced transplantable leukemias was studied. Resistance was developed by pretreatment of isologous mice with x-radiated tumor tissue. In general, the neoplasms grew more rapidly in preirradiated mice (400 r) than in normal mice, and at low inoculum concentrations a higher percentage of tumors was observed in the pre-irradiated animals. Different Moloney virus-induced leukemias were shown to cross-react. The resistance devel oped by pretreatment with x-radiated tumor suspensions of Moloney virus-induced leukemias did not inhibit the growth of a leukemia induced by the Rauscher virus. In BALB/c mice infected with Moloney virus transient interference with the growth of an isologous Moloney virus-induced leukemia was observed.