FIG. 4.

Blockade of the PD-1/PD-L1 pathway increases the expansion of antigen-stimulated HCV-specific T cells. CFSE-labeled PBMCs from two separate HLA-A2-positive patients were stimulated using the cognate peptide antigen for 6 days in the presence of IL-2 and anti-PD-L1 antibody (top panel) or anti-PD-1 antibody (lower panel). Results for an unstimulated control are also shown. The percentages of proliferating CFSE low- and CFSE high-HCV-specific HLA-A2⁺ CD8⁺ T cells are shown in each quadrant.