Survival of mice inoculated with irradiated WEHI-3B cells expressing exogenous cytokines. (A) Mice were injected with 5 × 10⁵ wild-type WEHI-3B cells (X). Mice were injected with 5 × 10⁵ irradiated WEHI-3B–lacZ (x) or WEHI-3B–GM-CSF (□) cells and then with 5 × 10⁵ wild-type WEHI-3B cells. (B) Mice were injected with 5 × 10⁵ irradiated WEHI-3B–lacZ cells (X) or with WEHI-3B–GM-CSF and WEHI-3B–TNF cells expressing 500 ng/mL GM-CSF and 10 ng/mL TNF (x); 10 ng/mL GM-CSF and 1 ng/mL TNF (○); 100 ng/mL GM-CSF and 1 ng/mL TNF (▵); 500 ng/mL GM-CSF and 1 ng/mL TNF (□); 10 ng/mL GM-CSF and 10 ng/mL TNF (◊); or 100 ng/mL GM-CSF and 10 ng/mL TNF (•). Seven days later, each mouse was injected with 5 × 10⁵wild-type WEHI-3B cells. (C) Mice were injected with 5 × 10⁵ irradiated WEHI-3B–lacZ cells (X) or with WEHI-3B–GM-CSF and WEHI-3B–IL-4 expressing 10 ng/mL GM-CSF and 100 ng/mL IL-4 (x); 100 ng/mL GM-CSF and 10 ng/mL IL-4 (□); 10 ng/mL GM-CSF and 10 ng/mL IL-4 (▵); 500 ng/mL GM-CSF and 100 ng/mL IL-4 (◊); 100 ng/mL GM-CSF and 100 ng/mL IL-4 (○); or 500 ng/mL GM-CSF and 10 ng/mL IL-4 (•). Seven days later, each mouse was injected with 5 × 10⁵ wild-type WEHI-3B cells. (D) Mice were injected with 5 × 10⁵ wild-type WEHI-3B cells (X). Seven days later, they were injected with 5 × 10⁵ BMMNCs from syngeneic mice inoculated with 5 × 10⁵ irradiated WEHI-3B–LacZ (x) or cytokine transfectants expressing 10 ng/mL GM-CSF and 1 ng/mL TNF (○) or 500 ng/mL GM-CSF and 10 ng/mL IL-4 (□) or with 10⁶ BMMNCs from mice inoculated with 5 × 10⁵ WEHI-3B–GM-CSF and WEHI-3B–IL-4 cells expressing 500 ng/mL GM-CSF and 10 ng/mL IL-4 (•).