CD4 and hepatocellular carcinoma: Consistently, when dividing the density of CTLs and CD4+CD25+ cells in HCC tissues into the high and low density by using the mean density as a cut-off value, patients with either deletion spanning pre-S2 gene segment or high percentage of pre-S2 plus pre-S1 + pre-S2 deletion were significantly associated with high density of Tregs in HCC tissues (P < 0.0001) (Tables 1 and 2).