CD4^dimCD8^bright cells recognize an antigen-specific target more than CD4^–CD8⁺ T cells.(A) CD8⁺ T cells were isolated by negative immunoselection (i), and the cells were either untreated or treated with CMV pp65 and SEB for 6 days. Freshly purified CD8⁺ T cells from the same donors are denoted as day 0. On day 6 after treatment, viable T cells were gated (ii) and further analyzed for CD4^–CD8⁺ or CD4^dimCD8^bright expression as shown after SEB stimulation (iii). (B) From the CD4^–CD8⁺ or CD4^dimCD8^bright T-cell population gates shown in panel A, percentages of CMV tetramer-positive cells were determined. Data in panel B are representative of 4 CMV IgG⁺/HLA-A*0201⁺ donors, and values are presented as median fold increase from day 0 (fresh) samples. CMV pp65/nonspecific tetramer refers to priming with CMV pp65 but staining with an EBV-tetramer (negative control). Asterisk denotes significant value (P = .03) using the Friedman Q Test. (C) Representative flow diagram from 1 donor is shown.