Phenotypic analysis of tumor-infiltrating lymphocytes in hepatocellular carcinoma.

Objective: Tumor may induce local immunosuppression and make the tumor-infiltrating lymphocytes (TILs) functionally inhibited and lose the antitumor effects. Therefore, we did the phenotypic analysis of TILs in hepatocellular carcinoma (HCC) tissues.

Methods: Lymphocytes were isolated from paired HCC tissues (TILs) and the corresponding non-tumor liver tissues (non-tumor-liver infiltrating lymphocytes, NILs) of 28 patients and were subjected to flow cytometric analysis.

Results: Compared with the non-tumor portion, HCC tissues had less intensity of lymphocyte infiltration. TILs had higher CD3+/CD56+ ratio than NILs. Around 70%-90% NILs or TILs expressed the antigen-experienced or memory phenotypes. Around 60%-70% CD4+ or CD8+ NILs and TILs expressed the activation markers CD69 and HLA-DR. However, we found that CD25 is under-expressed in both the CD8+ NILs and TILs. In addition, more percentage of CD4+ CD25+ T cells was detected in the TILs than in the NILs.

Conclusions: HCC tissues had less lymphocytes infiltration. Most of infiltrating lymphocytes from the HCC tissues and the corresponding non-tumor liver tissues were activated and expressed antigen-experienced phenotypes. However, the CD25 was underexpressed in the CD8+ TILs and the CD4+ CD25+ T cells were increased in the TILs. These factors might impair the antitumor immunity in HCCs.