Equivalent efficiency of pDCs and CD11c⁺ DCs to restimulate the HLA-A*0201–restricted influenza MP–specific CTL memory response.

T cells, pDCs, and CD11c⁺ DCs were purified from HLA-A*0201⁺ PBMCs. T cells were cocultured with pDCs or CD11c⁺ DCs infected by influenza virus or pulsed with influenza MP_(58-66) peptide. (A) Then, 7 days later, the presence of HLA-A*0201–restricted MP-specific CD8⁺ T cells in the cocultures and in a frozen sample of unstimulated T cells was measured by staining with PE-conjugated tetrameric complexes of MP_(58-66)/HLA-A*0201. A PE-conjugated tetrameric complex of LMP2/HLA-A*0201 was used as a control. (B) IL-3 pDCs or CD11c⁺ DCs pulsed with influenza MP_(58-66)peptide were cocultured at 5 different DC/T-cell ratios. Then, 7 days later, the presence of HLA-A*0201–restricted MP-specific CTLs in the cultures was measured by tetramer staining. (C) pDCs or CD11c⁺ DCs infected by influenza were cocultured at 5 different DC/T-cell ratios. Then, 7 days later, the presence of HLA-A*0201–restricted MP-specific CTLs in the cultures was measured by tetramer staining. (D) Then, 7 days later, IFN-γ production by HLA-A*0201–restricted MP-specific CD8⁺ T cells in the cocultures and in a frozen sample of unstimulated T cells was assessed by IFN-γ ELISPOT using unpulsed or MP peptide–pulsed T2 as presenting cells. (E) Cytolytic activity of HLA-A*0201–restricted MP-specific CTLs in the cocultures and in a frozen sample of unstimulated T cells was assessed by ⁵¹Cr release assay using unpulsed or MP peptide–pulsed T2 cells as target cells.