FIG. 5.

Reduced A2-PPI_15–24 CD8 T-cell cytotoxicity is due to reduced activation when recognizing wild-type peptide. A and B: A2-PPI_15–24 CD8 T-cell clones were incubated with either wild-type peptide-pulsed islet cells or islet cells presenting heteroclitic peptides with low, medium, or high affinity for PPI_15–24-TCR (see Table 1 for details). As pHLA affinity for TCR increases, so does intracellular TNF-α production and expression of degranulation marker CD107a by the clone (representative of n = 2). C: This finding also correlates with the percentage of specific lysis; high TCR affinity peptide-pulsed islet target cells are lysed to a level comparable to target cells pulsed with pp65_495–503 peptide in the presence of A2-CMVpp65_495–503 CD8 T-cell clone. Cytotoxicity assay bars represent means of triplicate assay wells; error bars show SEM. CTL, cytotoxic T lymphocyte; WT, wild type. (A high-quality color representation of this figure is available in the online issue.)