PDC depletion but not B-cell depletion abrogates the CpG ODN-induced enhancement of peptide-specific CD8⁺ T-cell responses. PBMCs from HLA-A2–positive donors were depleted of PDCs, B cells, or both; enriched for CD8⁺ T cells; and then stimulated with the HLA-A*0201–restricted Flu matrix_58-66 or Melan A_26-35 A27L peptide in the presence or absence of ODN 1585 and ODN 2006, respectively. After 12 days the cells were stained with the corresponding tetramers, and the percentage of peptide-specific cells within all CD8⁺ cells was determined by flow cytometry. Mean ± SEM of 3 individual donors are depicted. *P < .05.