Figure 8.

HCV antigens induce regulatory CD8⁺ T cells. (A–D) Four independent experiments showing that LILs derived from four HLA-A2⁺ patients suppress HCV-specific proliferation by autologous PBMCs only when stimulated with HCV peptides (^HCVLILs) but not when left unstimulated (LILs). In particular, HLA-A2⁺ PBMCs were cocultured with autologous LILs in the presence or absence of both HLA-A2–related HCV peptides (NS3_1073–1081, NS3_1406–1415, and NS4_1851–1859) and soluble recombinant chimeric NS3/NS4. In some wells, anti–IL-10 Ab was added. (E and F) Two control experiments showing that LILs derived from two HLA-A2⁺ patients suppress HCV-specific proliferation by autologous PBMCs only when stimulated with HCV peptides (^HCVLILs) but not when stimulated with irrelevant HLA-A2–related HIV peptides (pol_919–927, nef_94–102, and env_49–57) (^HIVLILs). After 6 days of coculture, 1 μCi [³H]thymidine was added to the cultures and the radioactivity incorporated by cells was determined after 18 hours. The cpm values of PBMCs (in the absence of LILs) in response to NS3/NS4 were calculated after subtraction of background and are indicated in parenthesis. The percent of suppression was calculated with the following formula: (PBMC-LIL coculture cpm / PBMC cpm) × 100.