Considering the higher FOXP3+ Tregs/CD4+ T cell and ICOS+ FOXP3+⁄FOXP3+ cell ratios in intratumoural tissues and higher suppressive capacity, we speculate that ICOS+ FOXP3+ Tregs may be the main immunosuppressive cell in HCC. The gene discussed is ICOS; the disease is hepatocellular carcinoma.