To test this hypothesis,

we first showed that CD3− infiltrating cells (non-T cells) expressed negligible levels of IFN-γ (not shown), and tumor-infiltrating T cells expressed high levels of IFN-γ (Fig. 1D). Ceritinib ic50 The levels of IFN-γ+ T cells were higher in HCC tissues compared to adjacent tissues (Fig. 1D). Thus, tumor-infiltrating T cells are the major source of IFN-γ in HCC. Then we examined the potential effect of tumor-infiltrating T-cell-derived IFN-γ on KC galectin-9 expression. We cocultured normal blood CD14+ monocytes with T cells from HCC tissue or adjacent tissue. Tumor-infiltrating T cells were superior at inducing galectin-9 expression on monocytes as compared to adjacent T cells (Fig. 1E). The induction was blocked by neutralizing antibody against IFN-γ (Fig. 1E). To further support the stimulatory role of IFN-γ, we showed that recombinant IFN-γ induced galectin-9 expression on monocytes (Fig. 1E). Additionally, we isolated KCs from relatively normal liver tissues in patients with hepatic hemangiomas, performed similar experiments, and confirmed the stimulatory effects of IFN-γ derived from HCC-associated T cells on the expression of KC galectin-9

(Fig. 1F). The results demonstrate that tumor-infiltrating T-cell-derived IFN-γ contributes to the increased galectin-9 expression on KCs in the HCC microenvironment. Galectin-9 is the ligand for Tim-3. After determining the expression and regulation of galectin-9 in the HCC microenvironment, we further studied the expression of Tim-3. Flow cytometry selleck inhibitor analysis showed that Tim-3 was expressed on Tyrosine-protein kinase BLK tumor-infiltrating CD4+ and CD8+ T cells. In HBV-positive patients, the levels of Tim-3+CD4+ T cells were higher than that of CD8+ T cells (Fig. 2A,B). Furthermore, Tim-3+ T cells were largely found in HCC tissues, not in the adjacent tissues (Fig. 2A,B). In

HBV-negative patients, the percentages of Tim-3+ T cells were less than 3% in both HCC and adjacent tissues (Fig. 2A). In line with this, multiple-color fluorescent staining demonstrated that there were higher numbers of Tim-3+CD4+ cells in snap-frozen HCC tissues than adjacent tissues (15 ± 3% versus 4 ± 2%) (Fig. 2C). As Tim-3+ T cells were basically detected in HBV-associated HCC, we extended our studies further to include large numbers of paraffin-fixed HBV-associated HCC tissues with conventional immunohistochemistry staining (Fig. 2D). In line with flow analysis and multiple-color fluorescent staining, there were higher numbers of Tim-3+ cells in HCC tissues than adjacent tissues (12 ± 8 versus 2 ± 2) (Fig. 2D). These results indicate that Tim-3 expression is increased on T cells infiltrating the HCC microenvironment. We further evaluated the pathological relevance of Tim-3 expression in HBV-associated HCC. Based on conventional immunohistochemistry staining in paraffin-fixed HCC tissues (Fig.