Figure 6.

M_p5 primes naïve T cells that are primarily cross-reactive. In the right lower quadrant for each T cell line, numbers separated by a slash indicate the percent of T cells specific for NS3₁₄₀₆/MFI. The percent of tetramer bound cells is shown using L_p5 (top row) or M_p5 (bottom row). Representative ICS data are shown for one line to the right of the FACS plots in each panel. A. Priming naïve cells with L_p5 peptide resulted in L_p5-specific responses that were cross-reactive for the M_p5-epitope as shown for three representative lines. The percent of T cells specific for L_p5 was usually higher and the MFI was always higher for L_p5 than M_p5 tetramer. Although cross-reactive, better IFN-γ production was observed in response to L_p5 versus M_p5B. For the T cells lines generated with M_p5 peptide, parallel staining with either M_p5 or L_p5/A*0201-MHC tetramers demonstrated that 8 of these lines were cross-reactive to the L_p5 epitope, displaying a similar or higher MFI, when stained with the L_p5 multimer, as shown for three representative lines. The percent of T cells specific for L_p5 and M_p5 and the MFI were usually equivalent. Responses vigorous enough to assess for cytokine production were very rare, but better or equivalent IFN-γ production was observed in response to M_p5 as compared to L_p5 for the lines that recognized both. C. Six of the 14 lines generated by M_p5 priming demonstrated a higher MFI after staining with the M_p5-multimer than the L_p5-multimer and one a much larger percent of M_p5 specific cells (25 vs. 0.1%), suggesting they were more specific for M_p5 and where assessed, they also produced more IFN-γ in response to M_p5.