Inhibition of pulmonary metastases of B16 melanoma with irradiated tumor cells and BCG.

When the tumor-bearing leg of C57BL/6J mice was amputated 16 days after SC inoculation of 10(6)B16 melanoma cells, all the amputated mice died of pulmonary metastases. Transfer of lungs from the amputated to normal syngeneic mice revealed tumor cells in the lungs just after amputation. Repeated weekly injections of BCG and irradiated tumor cells, beginning 24 h after amputation of the tumor-bearing limb, prolonged the survival only of mice presensitized to BCG. Injections of BCG or irradiated melanoma cells alone, or neuraminidase- and mitomycin C-treated tumor cells or of Levamisole had no effect, but injections of ConA-coated tumor cells slightly prolonged the survival of the amputated mice. Both BCG and B16 cells induced humoral and cell-mediated immunity but there was no cross-reactivity between BCG and B16 cells.