CD274 and neoplasm: PD-L1 is also expressed by immunocytes found within the TME, including lymphocytes, macrophages, and dendritic cells.3 We obtained preliminary data showing that PD-L1 is expressed by peripheral monocytes, in accordance with other findings for malignancies.5 6 Tumor-infiltrating macrophages (TAMs), which originate mainly from peripheral monocytes, also showed high PD-L1 expression.