Infiltration of tumor-associated macrophages is involved in tumor programmed death-ligand 1 expression in early lung adenocarcinoma.

Programmed death-ligand 1 (PD-L1) is an immune modulator that promotes immunosuppression by binding to programmed death-1 of T-lymphocytes. Although tumor cell PD-L1 expression has been shown to be associated with the clinical response to anti-PD-L1 antibodies, its concise regulatory mechanisms remain elusive. In this study, we evaluated the associations of tumor PD-L1 expression and immune cell infiltrating patterns in 146 cases of early lung adenocarcinoma (AC) to investigate the possible extrinsic regulation of tumor PD-L1 by immune cells.