Active immunoprophylaxis and immunotherapy in two mouse lymphoma models.
Injections of appropriate numbers of irradiated tumor cells produced antibodies against tumor cell-surface antigen(s) in both syngeneic tumor models studied: the early transplant generations of the spontaneous L2 lymphoma in AKR/J mice and the chemically induced EL 4 lymphoma in C57BL/6J mice. No antibody was detected in normal or nonimmunized tumor-bearing mice. Tumor inhibitory or enhancing activity was not demonstrated by these antibodies. Immunoprophylaxis or cell-mediated immunity against the L2 lymphoma was not observed after injections of irradiated L2 cells and/or BCG into AKR mice. However, injections of irradiated EL 4 cells alone were effective in immunoprophylaxis against as many as 10(6) EL 4 cells and in immunotherapy against 10(2) EL 4 cells per mouse. The addition of BCG injections made immunotherapy with irradiated EL 4 cells effective against a load of 10(4) EL 4 cells/mouse, though BCG alone was not effective for immunoprophylaxis against EL 4 cells. Resistance to EL 4 could be transferred with viable syngeneic peritoneal or nucleated spleen cells. In both tumor models, an ongoing delayed hypersensitivity reaction to BCG alone apparently did not inhibit bystander tumor cells even when tumor cells were mixed before inoculation with viable BCG. In neither tumor model were concanavalin A-coated tumor cells more potent for immunoprophylaxis than were irradiated tumor cells alone.