In a study that will be published in Nature Communications on May 28, 2021, a research team led by Dr. Yuan Liu from Georgia State University reports that intratumoral SIRPalpha-deficient macrophages activate tumor antigen-specific cytotoxic T cells to eliminate various syngeneic cancers under radiotherapy. Their study identifies SIRPalpha as a master regulator controling macrophage immune responses and has demonstrated that intratumoral injection of SIRPalpha-depleted macrophages combined with local radiation is an effective strategy to treat different tumors