CD4 and hepatocellular carcinoma: Third, a lack of CD4+ T cell help and the action of Treg may also contribute to the observed functional defects.18 Indeed, the important role of Treg in the immunobiology of HCC is suggested by the enrichment of these cells in HCC patients, a negative association with patient survival, and the unmasking of AFP‐specific CD4+ T‐cell responses after in vivo depletion of Treg in HCC patients.18 Of note, we also observed Treg enrichment in tumor and liver tissue in HCC patients.