Figure 1.

CD47-SIRPα signaling and pro-phagocytic cues between macrophages and solid tumor cells. (A) Fc regions of tumor-opsonizing antibodies bind to Fc receptors on macrophages, and Fab regions bind to tumor cell antigens. These signals act as a pro-phagocytic cues, but phagocytosis is ineffective when CD47 is only partially blocked by anti-CD47. (B) Complete knockout (KO) of tumor cell CD47 to ablate CD47-SIRPα signaling without a pro-phagocytic signal results in ineffective phagocytosis. (C) Both tumor cell CD47 KO (or anti-SIRPα block on macrophages) and tumor-opsonizing antibodies results in effective phagocytosis.