Fig. 1.

P8 V to A mutation in the NS3₁₃₇₆ epitope impairs IL-2 production in a cognate CD4 T cell clone. (A) Using an overnight intracellular cytokine staining assay, the E to A and V to A amino acid changes at positions P8 and P9, respectively, of the NS3₁₃₇₆ (YGKAIPLEVI) epitope were analyzed both separately and in combination for their ability to stimulate IFN-γ and IL-2 production in a CD4 T cell clone specific for the epitope. Representative flow cytometry data are shown, and values in the lower left, upper left, and upper right quadrants represent percentages of gated CD3⁺CD4⁺ cells that are IFN-γ⁻/IL-2⁻, IFN-γ⁺/IL-2⁻, or IFN-γ⁺/IL-2⁺, respectively. (B) Titrated concentrations of the NS3₁₃₇₆ WT and double mutant NS3₁₃₇₆ M1 peptides were analyzed for their ability to stimulate the CD4 T cell clone 3D to produce IFN-γ and IL-2 in an overnight intracellular cytokine staining assay. Representative results are shown. Values in the lower left, upper left, and upper right quadrants represent percentages of gated CD3⁺CD4⁺ cells that are IFN-γ⁻/IL-2⁻, IFN-γ⁺/IL-2⁻, or IFN-γ⁺/IL-2⁺, respectively.