Synergistic Reversal of Intrahepatic HCV-Specific CD8 T Cell Exhaustion by Combined PD-1/CTLA-4 Blockade
Figure 3
Intrahepatic HCV-specific T cell dysfunction can be reversed synergistically by combined PD-1/CTLA-4 blockade.
(A) Effect of inhibitory receptor blockade on HCV-specific IFN-γ and TNF-α production by CD8 and CD4 T cells from liver and blood. The bar graphs show the frequency of CD8 (upper graphs) and CD4 (lower graphs) T cells with HCV-specific intracellular IFN-γ and/or TNF-α expression in liver-derived (left panel, n = 6) and blood-derived (right panel, n = 8) lymphocytes isolated from chronic HCV patients and cultured for 7 days in vitro with 15mer overlapping peptides spanning the entire HCV NS3 protein (pNS3) in the presence of isotype control or blocking antibodies. The 7-day cultures were further stimulated for 6 hours with media alone or with pNS3 before intracellular IFN-γ and TNF-α staining. The %IFN-γ−TNF-α+ (blue bar), %IFN-γ+TNF-α+ (red bar) and %IFN-γ+TNF-α− (yellow bar) T cells are stacked together in each case to show total cytokine+ cells. (B) Representative flow cytometry plots showing HCV NS3 and Flu-specific IFN-γ and TNF-α production in vitro in liver-derived CD8 T cells from chronic HCV patient C21 following 7 days of culture with NS3 or Flu-derived peptides in the presence of isotype or blocking antibodies. Flow cytometry plots on the far left shows the PD-1 and CTLA-4 expression in liver-derived CD8 T cells directly ex vivo.