We used ESTIMATE and ssGSEA to estimate the tumor-infiltrating immune cells and immune scores for each HCC-patient sample and observed that the PTEN low-expression group had much higher scores in some immune cells, especially CD8 T cells, NK cells, B cells, and macrophages, which can activate the antitumor immunity and revive the tumor-killing capability in the HCC tumor microenvironment. The gene discussed is CD8A; the disease is neoplasm.