Inhibition of tumor growth depends on Th1 lymphocytes. (A) EpCAM-primed Th0/Th2 cells are unable to protect against CT26-EpCAM tumor cells. (B) EpCAM-primed Th1 cells protected against CT26-EpCAM tumor cells. (C) EpCAM-primed Th1 cells protected against CT26-EpCAM tumors and A20-EpCAM tumor cells but not against A20 wild-type lymphoma. T-cell cultures and in vivo experiments were performed as described as in “Methods.”