CD8⁺ T-cell responses to WT1 in donors and patients with ALL after SCT. (A) Tetramer analysis of PBMCs was performed by 6-color flow cytometry. Longitudinal data from patient 1 are presented. WT1/HLA-A*0201⁺ CD8⁺ T cells were gated on CD3⁺ events after passing through a small lymphocyte gate; HIV/HLA-A*0201 tetramer was used similarly as a negative control. (B) Comparison of frequency of WT1/HLA-A*0201⁺ CD8⁺ T cells in samples before SCT and after SCT. The values represent the maximal WT1/HLA-A*0201⁺ CD8⁺ T-cell response for each patient before and after SCT. Bars represent means. (C) IFN-γ production by CD8⁺ T cells in PBMC samples from patient 1, cultured for 6 hours with (top panel) or without (negative control; bottom panel) WT1 peptide. Results are expressed as percentages of CD8⁺ T cells. (D) Frequencies of WT1-specific CD8⁺ T cells by tetramer analysis () and WT1-specific IFN-γ producing CD8⁺ T cells ().