PD-L1 expression on tumor-infiltrating immune cells is highly associated with M2 TAM and aggressive malignant potential in patients with resected non-small cell lung cancer

•We evaluated PD-L1 expression on tumor cells (TCs) and immune cells (ICs).•Relationship between M2 tumor-associated macrophages (TAMs) and PD-L1 was studied.•PD-L1 expression on TCs and ICs was higher in patients with M2 TAM-high tumors.•PD-L1 on ICs rather than TCs was more related to aggressive malignant behaviors.•The presence of M2 TAMs might affect PD-L1 expression both on TCs and ICs in NSCLC.