IMMUNE RESPONSES TO TUMORS Adaptive immne responses,mainly mediated byTcells,have been shown to control the development and progression of malignant tumors 品 Target cel The principal mechanism of adaptive imIMMUNE RESPONSES TO TUMORS The principal mechanism of adaptive immune protection against tumors is killing of tumor cells by CD8+ CTLs Adaptive immune responses, mainly mediated by T cells, have been shown to control the development and progression of malignant tumors