CD274 and melanoma: Notably, CD163+ tumor-associated macrophages (TAMs) in melanoma express both PD1 and PD-L1, and blockade of PD-L1/PD1 signals by anti-PD1 Abs activates TAMs [67,68], leading to the production of TAM-activating factors such as sCD163 and chemokines in the serum of melanoma patients [57].