HBV‐specific CD8 T cells present higher TNF‐α expression but lower cytotoxicity in hepatocellular carcinoma

Summary Tumor necrosis factor (TNF)‐α is largely regarded as a proinflammatory cytokine, but several recent researches have demonstrated that TNF‐α could possess immunoregulatory roles with potential to suppress anti‐tumor immunity. Chronic hepatitis B virus (HBV) infection is a major risk factor of hepatocellular carcinoma (HCC), and HBV‐specific CD8 T cells could exert anti‐tumor roles in HCC patients. Here, we found that HBV‐specific CD8 T cells, both in the peripheral blood and in the tumor microenvironment, were more enriched with TNF‐α‐expressing cells than interferon (IFN)‐γ‐expressing cells. Compared to IFN‐γ‐expressing HBV‐specific CD8 T cells, TNF‐α‐expressing HBV‐specific CD8 T cells presented lower expression of inhibitory checkpoint molecules, including programmed cell death (PD)‐1, T cell immunoglobulin mucin‐3 (TIM‐3) and cytotoxic T lymphocyte antigen (CTLA)‐4. HBV‐specific CD8 T cells could mediate the lysis of autologous primary tumor cells, and the inhibition of TNF‐α could further elevate their cytotoxic capacity. Subsequently, we demonstrated that TNF‐α inhibition in HBV‐specific CD8 T cells could significantly increase granzyme B (GZMB) and perforin 1 (PRF1) expression while having no effect towards granzyme A (GZMA) expression. The addition of exogenous TNF‐α at low levels had no consistent effect on the expression of GZMA, GZMB and PRF1, but at higher levels, exogenous TNF‐α significantly reduced GZMA, GZMB and PRF1 expression. Overall, these results suggested that TNF‐α‐expressing cells probably presented a deleterious role in HCC but were enriched in HBV‐specific CD8 T cells.