Detection by tetramer of HLA-A*02-restricted, ASP-YL9-specific CD8+ T cells in HIV+ patients. Following in vitro restimulation of PBMCs with ASP-YL9 peptide, cell lines from 6 HLA-A*02+ HIV+ patients (Pats. 26 to 31) and 4 HLA-A*02+ seronegative donors (SN 1 to 4) were stained for CD4 and CD8 in combination with the HLA-A*02/ASP-YL9 tetramer. (A) Gating strategies and illustration of tetramer staining for SN2, Pat.28 and Pat.29. In Pat.28, 0.06% tetramers + cells were detected corresponding to 0.11% of CD8+ T cells. No tetramer + cells were detected among CD4+ cells. In Pat.29, no significant tetramer+ population was detected (Fisher-exact test). (B) Percentages of HLA-A*02/ASP-YL9 tetramer+ cells within CD8+ T cells of HIV+ patients and seronegative donors.