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

• Published in: Lung cancer (Amsterdam, Netherlands) Netherlands), 2019-10, Vol.136, p.136-144
• Main Authors: Sumitomo, Ryota, Hirai, Tatsuya, Fujita, Masaaki, Murakami, Hiroaki, Otake, Yosuke, Huang, Cheng-long
• Format: Article
• Language: English
• Subjects: CD163; Immune cells; Macrophage; PD-L1; Prognosis
• ISSN: 0169-5002; 1872-8332
• DOI: 10.1016/j.lungcan.2019.08.023

•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. PD-L1 expression on tumor cells (TCs) and tumor-infiltrating immune cells (ICs) plays important roles in regulating the antitumor T cell response. However, the mechanistic and clinical significance of the effect of PD-L1 on TCs versus ICs remains unclear. On the other hand, tumor-associated macrophages (TAMs), M2 macrophages in particular, can promote tumor progression. We evaluated PD-L1 expression on TCs and ICs using Ventana SP263 assay and the stromal M2 TAM distribution using CD163 staining in 160 consecutive patients with resected non-small cell lung cancer (NSCLC). PD-L1 expression on TCs and ICs was significantly higher in stromal M2 TAM-high group than in stromal M2 TAM-low group (p