CD274 and neoplasm: Although our co-culture with SNK6R and THP-1 cells could not exactly represent in vivo situation due to the presence of various factors influencing the expression of PD-L1 on macrophages, the transfer of exosomes carrying PD-L1 on their surface from tumor cells to macrophages might occur in our experiment considering the well-known role of exosomes in the crosstalk between tumor cells and tumor-associated macrophages [28].