CD4 and colorectal carcinoma: YGYZ and its FMT inhibited LM of CRC with safety, inhibited CD11b+Ly6G+ and CD11b+Ly6C+ cells in the pre-metastatic stage, decreased CD11b+Ly6G+ cells in the metastatic stage, reduced immunosuppressive factors such as Arg-1, TGF-β, and IL-10, and improved the CD4+/CD8+ T-cell ratio, regulating liver PMN.