MARCO and neoplasm: However, expression of programmed death ligand-1 (PD-L1) on both tumor cells and immune cells has previously been shown to be strongly associated with dMMR-status in the present cohort (17), and in this study, significant associations were observed between CD163+ macrophage infiltration and PD-L1 expression on tumor cells, and between MARCO+ macrophages and PD-L1 expression on both tumor cells and immune cells.