Within the TME, MDSCs inhibit T cell-mediated specific anti-tumor immunity, as well as non-specific anti-tumor immunity mediated by NK cells and macrophages, by expressing high levels of Arg1, iNOS, and ROS.<h4>Methods</h4>This study used the Lewis lung carcinoma cell line to establish a lung cancer xenograft model; MDSCs were isolated from the spleens of these mice for subsequent experiments. Here, ARG1 is linked to neoplasm.