GM-CSF–secreting tumor cell vaccination in WT, GM-CSF, IL-5, or βc knockout C57BL/6 mice. (A) GM-CSF^−/−, βc^−/−, WT, or (B) IL-5^−/− and WT C57BL/6 mice were immunized subcutaneously on the abdomen with 10⁶ irradiated, B16-GM cells (5 per group). One week later, the vaccinated mice as well as the unvaccinated WT controls, were challenged subcutaneously on the back with 5 × 10⁵ live B16 cells. The difference observed in survival time between B16-GM–vaccinated βc^−/− mice and unvaccinated WT controls is not statistically significant. This experiment is representative of 3 independent experiments. (C) Tumorogenicity of B16-F10 cells in different knockout mice. Survival of WT and indicated knockout C57BL/6 mice inoculated with 5 × 10⁵ B16-F10 cells. This experiment is representative of 3 independent experiments.