Single cell analysis for CD4+/CD8+ T cells in HCC. CD4/CD8 double-positive T cells were enriched at the tumor margin and co-expressed with PD-1/HLA-DR/ICOS/CD45RO; 11 CD4+/CD8+ T cell subsets with different cytotoxicity, depletion and activation scores were further described. The gene discussed is ICOS; the disease is hepatocellular carcinoma.