Effect of HLA-A type and HLA blocking antibodies on cytotoxic activity of the bcr-abl–specific T-cell clone (P218). Target cells in each case were monocytes pulsed with the 16 mer bcr-abl peptide P2. Results are expressed as mean ± SD specific lysis at an E:T ratio of 10:1. *Significant lysis (P < .0002). Cytotoxicity is shown against autologous and HLA-A matched monocytes but not against HLA-A mismatched monocytes. Addition of anti-HLA-A24 antibodies to assays blocked cytotoxic activity.