CD4+ CTLs have been demonstrated to exert antitumor activity in mice through granular exocytosis,12, 13, 21 and their therapeutic potential in cancer was recently emphasized.29-32
However, limited information is available on the functional Gefitinib roles of these cells in human cancers. This study comprehensively characterized CD4+ CTLs in vivo in HCC patients and found that reduced numbers of CD4+ CTLs are associated with poor survival and a high recurrence of HCC. The present study indicated that CD4+ CTLs were enriched in nontumor regions, and were significantly increased in early stage HCC patients. Furthermore, the loss of CD4+ CTLs was closely associated with HCC disease progression. We also found that CD4+ CTLs predominantly expressed interferon-gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) (Supporting Fig. 4C). These data suggest that these cells might participate
in antitumor immunity. Most important, circulating and tumor-infiltrating CD4+ CTLs in HCC patients exhibited a strong prognostic value for survival times in naturally progressing HCC patients, and MEK inhibitor in terms of the DFS and OS rate in patients who had undergone surgical resection. The Cox’s proportional hazards model showed that CD4+ CTLs are independent prognostic factors for naturally progressing survival, DFS, and OS rates. Taken together, these results strongly indicate that the number of CD4+ CTLs is a prognostic marker for human HCC progression. Notably,
MCE we found that there were intrinsic qualitative defects in CD4+ CTLs through the detection of CD107a mobilization. CD107a is a lysosomal-associated membrane glycoprotein that surrounds the core of the lytic granules in cytotoxic T cells. Upon T cell receptor (TCR) engagement, CD107a is exposed on the cell membrane of cytotoxic T cells.26, 27 The surface mobilization of CD107a by CD4+ T cells is associated with the release of cytolytic granules.27 Our study indicated that CD4+ CTLs from HCC patients showed significantly lower levels of exocytosis of cytolytic molecules in response to TCR engagement compared with other groups of subjects. As such, the degranulation of CD4+ CTLs in HCC patients was functionally impaired and led to a small release of stored perforin and Gzm proteins from these cells. This study also elucidates the possible mechanism that underlies the functional impairment of CD4+ CTLs in HCC patients. Our data support the notion that the increased numbers of Treg cells may potentially impair CD4+ CTL function. On the one hand, the number of CD4+ CTLs in TILs, NILs, and peripheral blood were negatively correlated with an increase in the number of Treg cells. Our previous studies indicated that FoxP3+ Treg cells in TILs, NILs, and peripheral blood were significantly increased with the progression of HCC.