Polyfunctional CD8⁺ T_EM cells specific to apoptotic epitopes distinguish patients experiencing chronic infection.

<p>(<b>A,B</b>) Representative flow cytometry analyses of PBMCs from patients with acute HCV infection experiencing chronic infection (A) or undergoing infection resolution (B) that were stained with mAb to CD8 and pentamers complexed to the indicated apoptotic or viral epitopes. Cells were then stimulated with the relevant soluble peptides plus anti-CD28 mAb and processed for the detection of IL-17, IL-22, IFN-γ, IL-4, and IL-2 by ICS assay with the relevant mAbs. Counterplot analyses are gated on CD8⁺pentamer⁺ cells and show percentages of cytokine-producing cells. The percentage of cells is reported in each quadrant. The small histograms show ICS analyses of representative cytokine (IL-17, IL-22, IFN-γ, IL-4, or IL-2) production without antigenic stimulation by gated CD8⁺pentamer⁺ cells. (<b>C,D</b>) Peptide dose-response curves of cytokine-producing CD8⁺pentamer⁺ cells from patients with acute HCV infection experiencing chronic infection (C) or undergoing infection resolution (D). Cells were stained with the pentamers expressing the indicated peptides and stimulated for 6 h with the same soluble peptides. They were then processed for the detection of the different cytokines indicated by ICS assay. Values are shown with the background subtracted.