Differential Infiltration of T-cell Populations in Tumor and Liver Tissue Predicts Recurrence-Free Survival in Surgically Resected Hepatocellular Carcinoma

Background: /Objectives: Liver and tumor-infiltrating T cells in hepatocellular carcinoma (HCC) are heterogeneous, comprising the CD69+ tissue-resident T cell and the CD69- circulating T-cell populations. However, the impact of these distinct T-cell populations on patient prognosis is unclear; hence further studies are needed. Methods: Tumor and distant liver tissues from 57 HCC patients with various chronic liver disease etiologies were analyzed. Single-cell dissociation and flow cytometry were used to assess CD69+ and CD69- T-cell populations and their correlation with recurrence-free survival (RFS). Results: CD69+/CD69- subpopulations within CD4+ and CD8+ T cells varied by patient and alcohol etiology. CD69- populations among CD4+ T cells were less frequent in both tumor and non-tumor tissues of alcohol-related HCC patients (p< 0.05). Higher frequencies of CD69-CD4+ and CD8+ T cells in tumors and CD69+CD103+CD8+ T cells in liver tissues were associated with better RFS. CD69- T cells expressed lower PD-1 levels, indicating less exhaustion, with PD-1 expression inversely correlated with CD69- frequency. PD-1 ex-pression was higher on CD69-CD4+ T cells in alcohol-related HCC. Conclusions: We provided a detailed analysis of the heterogeneous characteristics of tumor- and liver-infiltrating T cells in HCC, emphasizing the distinct roles of CD69+ and CD69- cell populations and their impact on RFS. CD69+ T cells were associated with immune exhaustion and tumor aggressiveness, whereas CD69- T cells appeared to sig-nificantly contribute to the influence of alcohol intake on the immune landscape of HCC in the tumor microenvironment. However, further research should validate these findings in larger cohorts to enhance our understanding.