TAMs in the tumor stroma of HCC secrete pivotal cytokines (e.g., NF-α, IL-6, IL-23) and expand IL-17-producing CD4+ T helper 17 cells (Th17), which inhibit antitumor immunity by upregulating PD-1 and CTLA-4 (60). Here, CTLA4 is linked to hepatocellular carcinoma.