HIV peptide-specific cytotoxicity of T-cell lines infused into subjects after in vitro stimulation with HIV CTL epitope peptides from subjects 202 (A), 204 (B), 216 (C), 203 (D), 214 (E), and 226 (F ). Peptide-specific cytotoxicity was defined as the difference between the percentage of specific cytotoxicity in the presence or absence of peptide in a 4-hour ⁵¹Cr release assay at an E:T ratio of 20:1. T-cell line (▪) before and (□) after peptide exposure. For subject 226, the pretherapy T-cell line had lost HIV-specific cytotoxicity and the peptide selection was repeated three times to obtain sufficient antiviral activity to meet the infusion criteria (<25% HIV-specific cytotoxicity at an E:T ratio of 20:1). The background lysis of autologous B-LCL targets was less than 10%, except for T-cell line 202, for which it was 16%.