Response of bcr-abl peptide specific lines to b3a2 containing cell lysates. PBMC from donor NG were stimulated four times with b3a2 peptide pulsed autologous mitomycin C–treated PBMC. Peptide specificity and response to cell lysate was determined after the fourth stimulation, using the split-well method. Results show the proliferation of peptide-specific wells, when stimulated with mitomycin C–treated PBMC pulsed with (A) b3a2 and b2a2 patient lysates and (B) K562 cell lysate or HEL cell lysate. In each case control b3a2 peptide and b2a2 peptide responses are shown.