Bulk lines and clones derived from HIVIIIB virus–responsive CD8 T cells recognize IIIB and NL4-3 virus, but not autologous virus–infected CD4 T cell targets. A bulk cell line and clones were generated from CD8 T cells that produced IFN-γ after stimulation with HIVIIIB-infected CD4 T cell targets in a CDC stage B subject (no. 307). The cell line and one clone (N12-1) were then tested for lysis of control uninfected CD4 blasts (white bars) or enriched populations of IIIB (dark gray bars), autologous (light gray bars), or NL4-3 (black bars) virus–infected CD4 blasts at an effector/target ratio of 5:1. Data are presented as mean of experiments performed in triplicate. The epitope recognized by the cell line and clone was mapped to a 10mer region in nef, LWIYHTQGYF (amino acids 112–121). The autologous virus differed from the sequence by two amino acids (LWVYNTQGYF).