PDCD1 and hepatocellular carcinoma: The results showed that CD28+PD-1+ Tc-cell infiltration was significantly higher in HCC tissues than in adjacent tissues (Figure 6, P < 0.001), which is consistent with the bioinformatics analysis, indicating that CD28+PD-1+ Tc cells were significantly enriched in HCC and may contribute to immune modulation in the HCC TME.