Direct isolation of HA-1-specific cytotoxic T cells from HLA-A2^pos/HA-1^neg cord blood. Results from 3 (A, B, and C) HLA-A2^pos/HA-1^neg CB samples obtained from HLA-A2^pos/HA-1^pos mothers are shown. (A-C) Analysis of cells collected after the first enrichment sort for HA-1^A2 tetramer and CD8^pos cells. (D) CD45RA expression on HA-1^A2 tetramer^pos CD8^pos cells (gate R1, filled histograms) and tetramer^neg CD8^pos cells (gate R2, open histograms) from CB samples A, B, and C, respectively. (E-G) CD8 and HA-1^A2 tetramer staining of polyclonal cultures expanded after the enrichment sort followed by R1 sort of tetramer^pos CD8^pos cells from CB samples A, B, and C, respectively. (H) Cytotoxic activity of culture G, after a second expansion phase, against various target cells: HLA-A2^pos/HA-1^neg EBV-LCL (squares); HLA-A2^pos/HA-1^neg EBV-LCL pulsed with HA-1^H peptide (triangles); HLA-A2^pos/HA-1^pos leukemic cells (▾); autologous HLA-A2^pos/HA-1^neg CB PHA blasts (♦); and K562 cells (•). Insert in H shows the corresponding HA-1^A2 tetramer staining.