The objectives of our research during the next year will be to further explore the potential of passive and active immunotherapy in mouse model systems, and to increase our understanding of the mechanisms involved. Work is planned with four of our seven recently derived C57BL/6J tumors, which include two radiation-induced osteogenic sarcomas, two sarcomas, two chemically induced carcinomas, and a spontaneous lymphoma. Work is being completed on the antigenic strength of these tumors, in an effort to suggest a standardized quantitative method for determination of the immunogenicity of experimental tumors. Work will be done on passive immunotherapy of these tumors with antisera of defined specificity, and on active immunotherapy with irradiated unmodified tumor cells as well as with modified tumor cells. An attempt will be made to relate the results of immunotherapy with the immunogenicity of the tumor cells. Similarly, the relationship betweeen response to chemotherapy and immunogenicity of the tumor cells will be studied. Finally, a start will be made on a study of the cellular dynamics of the therapy process by methods that will focus on the whole animal rather than on in vitro methods.