Killing of APCs pulsed with native or heteroclitic peptides. Comparison between specific lysis of APCs pulsed with native (▪) and heteroclitic (▴) peptides by CTLs generated against the corresponding peptide and their calculated binding (FI). The results of the specific lysis are at an effector-target ratio of 30:1 and are mean values from experiments done in triplicate with samples from up to 3 different donors; the results of the measured binding are representative of at least 3 independent experiments performed on a total of 34 peptides. Diagonal lines represent best-fit regression analysis, with B value given.