Peptide-specific T-cell clones isolated from an ovarian cancer patient after immunization can lyse HLA-A2⁺ tumor cells overexpressing HER-2/neu protein. A p369–377–specific clone was examined for cytolytic activity against BLCL-A2 alone (open circles), p369–377-loaded BLCL-A2 (filled circles), or the HER-2/neu–overexpressing tumor cells, SKOV3 (open squares) and SKOV3-A2 (filled squares). SKOV3-A2 are SKOV3 cells stably expressing HLA-A2. Each point represents the mean of three replicates (± SEM). The absence of errors indicates a standard of the mean less than 1%.