Chen L, Cao MF, Xiao JF, et al. - By flow cytometry analysis, researchers explored the frequency of PD-1 expression on tumor-associated macrophages (TAMs) in mouse allografts and investigate the spatial distribution and clinicopathological significance of PD-11⁺ TAMs in 213 cases of human lung adenocarcinoma specimens by immunohistochemical staining. The expression of PD-1 was determined by both mouse and human TAMs. In comparison with PD-1^- TAMs, mouse PD-11⁺ TAMs possess unique transcriptional profile. The data suggested that in lung adenocarcinoma, PD-1⁺ TAMs have unique gene expression characteristics and PD-1+ TAMs in the tumor stroma is a potential prognostic factor, indicating that a better understanding of PD-1⁺ TAMs will be significant for immunotherapy of lung adenocarcinoma patients.