TCL1_71-78 is the minimal HLA-A*0201–binding epitope. (A) TCL1_65-79 peptide-specific T cells were incubated in the presence or absence of T2 cells and TCL1_65-79–derived truncated peptides. Flu matrix peptide (FMP_58-66) and Gag_77-85 peptide were used as controls. After 18 hours, the production of IFN-γ was determined in the supernatants by ELISA. (B) T2 cells were incubated with TCL1_65-79–derived truncated peptides, and the HLA-A2 binding affinity of each peptide was determined by flow cytometry. The T2 binding index was calculated as described under “Methods.” (C) TCL1_65-79 peptide-specific T cells were incubated with T2 cells pulsed with TCL1_65-79–derived truncated peptides or control HIV Gag_77-85 peptide, and a 4-hour ⁵¹Cr-release cytotoxicity assay was performed. The percentage of specific lysis is shown. (D) TCL1_65-79 peptide-specific CD8⁺ T cells or irrelevant T-cell line were stained with TCL1_71-78 or HIV Gag_77-85 tetramers and analyzed by flow cytometry. The percentage of tetramer positive T cells is shown. Data in panels A to D are representative of 3 independent experiments each.