Epitope recognition by NLV peptide specific CD8 T cells.

<p>(A) IFN-γ spots, each representing a CD8 T cell responding with IFN-γ production, formed upon sensitization of NLV peptide-specific murine (mCD8-NLV; left panel) and human (hCD8-NLV; right panel) cytolytic CD8 T-cell lines (CTLL) by NLV-peptide-pulsed NSG/HHD MEF at an effector-to-stimulator cell ratio of 0.1:1. MEF were pretreated with murine IFN-γ for 48h (filled bars) or left untreated (open bars) and were exogenously loaded with synthetic NLV- or non-cognate gp100_280-288-peptide at the indicated concentrations. Data are shown as mean of duplicates from one experiment representative of two performed. Error bars represent the range. (B) Structural avidity of antigen binding to mCD8-NLV and hCD8-NLV CTLL was quantified by dose-dependent HLA-A2.1/NLV tetramer binding in flow cytometry. The respective dissociation constant (K_D) was calculated from half-maximal tetramer binding obtained by Scatchard plot analysis. Dotted curves border the 95% confidence regions of the log-linear regression lines. MFI, mean fluorescence intensity. (C) HLA-A2.1 restricted presentation of NLV epitope by NSG/HHD MEF pretreated with murine IFN-γ for 48h (filled bars) or left untreated (open bars) and infected at an MOI of 4 with the indicated viruses for a total time of 22h until the end of the assay. Peptide presentation on the infected MEF during that period was detected in an IFN-γ ELISpot assay with mCD8-NLV (left panel) and hCD8-NLV (right panel) CTLL at an effector-to-stimulator cell ratio of 0.1:1. Data are shown as mean of duplicates from one experiment representative of two performed. Error bars represent the range.