As shown in Fig. 3D, we found that the proportion of CD4+CD25+FOXP3+ Treg cells was significantly higher in the advanced-stage (III–IV) HCC groups of various tumor sizes than in the control group; moreover, the proportion of CD4+CD25+FOXP3+ Treg cells was significantly higher in the large tumor size HCC group than in the small tumor size HCC group. Here, CD4 is linked to hepatocellular carcinoma.