IFNG and neoplasm: and host factors: Tregs cells directly or indirectly inhibit effector T cells; MDSCs cells directly inhibit immune function; M2 macrophages inhibit T cells through PD-L1/B7-H4 on the surface of tumor cells; IFN-γ promoting the expression of immunosuppressive molecules to inhibit the function of effector T cells, leading to immunosuppression and immune resistance.