Chronic inflammation, which is dominated by macrophage-involved inflammatory responses, is an instigator of cancer initiation. Macrophages are the most abundant immune cells in healthy lungs, and associated with lung tumor development and promotion. PD-L1 is a negative molecule in macrophages and correlated with an immunosuppressive function in tumor environment. Macrophages expressing PD-L1, rather than tumor cells, exhibits a critical role in tumor growth and progression. However, whether and how PD-L1 in macrophages contributes to inflammationinduced lung tumorigenesis requires further elucidation. Here, we found that higher expression of PD-L1 in CD11b + CD206 + macrophages was positively correlated with tumor progression and PD-1 + CD8 + T cells population in human adenocarcinoma patients. In the urethane-induced inflammation-driven lung adenocarcinoma (IDLA) mouse model, the infiltration of circulating CD11b high F4/80 + monocyte-derived macrophages (MoMs) was increased in pro-tumor inflamed lung tissues and lung adenocarcinoma. PD-L1 was mainly upregulated in MoMsThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.