sCAR-PPAb activated macrophages in a K562/ADR xenograft model. BALB/c nude mice were transplanted with K562/ADR cells subcutaneously. sCAR-PPAb were injected intratumorally for 7 days at 100μg/day. PBS injection served as the control. A. Tumors were harvested and F4/80 was analyzed for macrophage infiltration by immunohistochemistry. The control showed IgG isotype staining. Arrows point to cells stained with F4/80. Bars show 200μm (400 x). B. Tumors were analyzed using a transmission electron microscope. The arrow points to cells undergoing phagocytosis. Bars show 2μm.