CD38 and hepatocellular carcinoma: By gating on CD8+ or CD4+ T cells, a higher frequency of CD38+ can be observed on CD8+ T cells compared to that on CD4+ T cells, particularly on TILs, but not on the NILs and PBMCs (Figures 3A, B), suggesting that CD8+ T cells are the dominant CD38-expressing CD3+ T cells among the TILs in HCC tumors.