The density (mean ± standard error of the mean (SEM)) of CTLs and CD4+CD25+ cells in HCC tissues of the 40 HBV-related HCC patients was 18.03 ± 1.50 and 8.18 ± 0.87 cells/mm2, respectively (Fig. 3A,B). This evidence concerns the gene CD4 and hepatocellular carcinoma.