Frequencies of QYDPVAALF-specific CD8⁺ T cells in PBMCs of healthy HLA-A24⁺ and CMV-seropositive donors.

PBMCs were stimulated with either the CMV peptide QYDPVAALF or the control peptide RYLRDQQLL, derived from the HIV envelope protein, for IFN-γ production. After fixation and permeabilization, the cells were stained for CD8, CD69, and IFN-γ. The CD8⁺ subset was gated and analyzed by flow cytometry. The frequency of IFN-γ–producing cells is shown as the percentage of the total CD8⁺ T cells. The donors were all seronegative for HIV.