CD4^dimCD8^bright T cells recognize antigen more potently than CD4⁻CD8⁺ T cells. (A,C) Cumulative data of CD4⁻CD8⁺ and CD4^dimCD8^bright T cells staining for HIVgag (A) and CMVpp65 (C) tetramers from fresh cells (fresh), untreated cells at day 6 (Unt), or cells stimulated for 6 days with HIV pooled peptide (HIV) or CMVpp65 peptide (CMV) from HIV⁺ LTNP (A) or CMV⁺ donors (C). Data represent mean ± SD percentage of expression of tetramer-positive cells from at least 3 donors. P values between groups are indicated within the figure and based on 2-tailed unpaired t test analysis. (B,D) Representative dot plots of HIVgag (B) and CMVpp65 (D) tetramer binding.