Expression of CD28, SLAM, and CD56 by CD8⁺ T cells expanded in the presence of CpG PBMCs were stimulated in the presence or absence of CpG ODN (6 μg/mL) with the HLA-A*0201–restricted Flu matrix_58-66 peptide. After 10 to 14 days cells were harvested and stained with HLA-A2/Flu matrix_58-66 tetramers-PE, anti-SLAM^FITC, anti–PerCP, and Topro-3, or with HLA-A2/Flu matrix_58-66 tetramers-PE, anti–CD28-FITC, anti–CD8-PerCP, and anti-CD56 APC and were analyzed on a flow cytometer. HLA-A2/Flu matrix_58-66 tetramers⁺ CD8⁺ cells and HLA-A2/Flu matrix_58-66 tetramers^– CD8⁺ were gated, and the expression of the indicated surface antigen on these subpopulations was determined. Markers were set according to isotype controls, and the percentage of cells positive for the indicated marker is depicted. (A) Results from 1 representative experiment are shown. Upper arrow indicates peptide-specific CD8 T cells in upper right quadrant; lower arrow, peptide-nonspecific CD8 T cells in lower right quadrant. (B) Data from different donors (n = 14 [CD28]; n = 14 [CD56]; n = 6 [SLAM]) are presented as mean ± SEM. **P < .01. (C) Mean ± SEM from 3 different donors are shown. ODN 2137 and ODN 2243 are the GC control ODN to ODN 2006 and ODN 2216, respectively. *P < .05.