In summary, our findings reveal that (1) PTX3 expression tends to be silenced in colon tumor cells following tumorigenesis but can be sustained at high levels in stromal cells, (2) blockade of PTX3 with the specific antibody WHC-001 attenuates tumor growth by increasing the population of tumor-infiltrating cytotoxic CD8+ T cells and decreasing the population of tumor-infiltrating M2-like macrophages, and (3) the CREB1/CEBPB axis mediates the PTX3-induced promotion of M2 macrophage polarization (Fig. 6L). Here, CD8A is linked to neoplasm.