In this study, we show that the infusion of Irg1-deficient macrophages, but not neutrophils, into tumor-bearing mice exerts potent tumor-killing effects and also enhances the efficacy of anti–PD-(L)1 immunotherapy in the melanoma model (Fig. 6, E and F, and Fig. 7, A and B), in which most of TAMs should be from recruited monocytes. The gene discussed is ACOD1; the disease is neoplasm.