PDCD1LG2 and cancer: While unexposed monocytes have low expression of PDL1, CD163, and CD206 (Fig 3A; black solid lines), exposure to mf, similar to those of cancer cell lines, significantly upregulate the cell surface expression of PDL1 (inhibitory), PDL2 (M2/inhibitory), CD206 (M2), and VCAM-1(M1) (Fig 3A and 3B).