Hematopoietic-restricted lysis of CB-derived cytotoxic T-cell clones. (A) The cytotoxic activity of one representative HA-1-specific T-cell clone (1) is shown against fibroblasts (closed circles), fibroblasts pulsed with HA-1^H peptide (^*), and PHA blasts (×). The fibroblasts and PHA blasts are derived from the same HLA-A2^pos/HA-1^pos donor. (B-D) The cytotoxic activity of 3 HA-1-specific cytotoxic T-cell clones (clones 1, 2, and 3) is shown against 3 different HLA-A2^pos/HA-1^pos leukemic cells (▪, ▴, and ▾ ; acute lymphocytic lymphoma cells); HLA-A2^pos/HA-1^neg leukemic cells (○) and autologous HLA-A2^pos/HA-1^neg CB PHA blasts (⋄ or □).