CD8⁺ T-cell response to PR1 and WT1 vaccination by peptide/HLA-A2 tetramer analysis. Tetramer analysis of PBMCs was performed by 5-color flow cytometry. Longitudinal data from patient 8 are presented. PR1/HLA-A*0201⁺ and WT1/HLA-A*0201⁺ CD8⁺ T cells were gated on CD3⁺ events after passing through a small lymphocyte gate; HLA-A2–null tetramer was used similarly as a negative control.