Analysis of Wilms tumor 1 (WT1)-specific cytotoxic T lymphocytes (CTLs). (a) Before vaccination. (b) After vaccination. (c) At 31 months after the final vaccination. WT1-specific CTL levels before vaccination increased from 0.03 (a) to 0.08% at the final vaccination (b). At 31 months after the final vaccination, WT1-specific CTL levels increased to 0.10% (c).