Mature DCs derived from chronic HCV patients prime allogeneic T cells and stimulate antigen-specific syngeneic memory T cells. (A) Allo-MLR T-cell priming by iDCs and mDCs from noninfected (NI) donor no. 3 and chronic HCV patient no. 794 are shown. Error bars indicate ± SD. T cells cultured alone are represented by a filled triangle. (B) Allostimulatory responses of mDCs from all tested noninfected donors and chronic HCV patients were normalized to values of the noninfected donor at 30:1 to generate an allostimulatory index and were plotted as thin lines with patient identification numbers noted. Thick black line represents mean allostimulatory capacity. See Supplementary Table S2 for numeric values and additional data on iDC stimulation. (C) IFN-γ production by influenza-specific T cells stimulated with either uninfected (white portion of bar) or infected mDCs (black portion of bar) from all patients tested. Data from noninfected, responder, and chronic HCV patients are shown as spot-forming cells (SFCs) per 10⁶ T cells, plotted on a logarithmic scale. NR indicates fewer than 50 SFCs per 10⁶ T cells. Influenza responsiveness is patient specific and dependent on the individual's prior exposure to the virus. Therefore, patient responses may not be averaged across the sample population. Data on noninfected donors (buffy coats) present a range of influenza T-cell precursor frequencies (fewer than 50 to 2300 cells per 10⁶ T cells) and the percentage of responders as based on a signal greater than 50 spot-forming cells per 10⁶ T cells (88% responders; n = 25).