Verification of the immunogenicity of the identified HCMV-derived peptides in PBMCs from patients after allo-SCT. (A) Representative flow cytometric density plots of IFN-γ⁺/CD8⁺ T-cell frequencies after stimulation with a background control (HIV_Gag HLA-A∗03 or HIV-1 p17 HLA-B∗15) or HCMV-derived single peptides are shown. (B) Background-corrected peptide-specific T-cell frequencies of PBMCs from patients with HCMV seropositivity (red circles) or seronegativity (blue triangles) 180 days after allo-SCT after stimulation with HCMV-derived single peptides. PBMCs were also stimulated with pp65 peptides that were presented on the donors' alternative HLA allotype for comparative analysis. Each symbol represents 1 donor. The Mann-Whitney U test and Benjamini-Hochberg procedure for a false-positive discovery rate of <0.2 were used for statistical analysis (∗ P < .05). (C) PBMCs from an allo-SCT recipients with HCMV seropositivity (red) or HCMV seronegativity (blue) were longitudinally collected every 30 days from day +30 to day +180 (HLA-A∗03) or day +270 (HLA-B∗15). PBMCs were stimulated with the specified HCMV-derived single peptides. Background-corrected IFN-γ⁺/CD8⁺ T-cell frequencies are shown. The used specific peptides can be identified by the symbols shown in Figure 5C.