Chromium release assay for the verification of R3-specific cytotoxic activity of CD8⁺ T lymphocytes in patient no. 1 with acute myeloid leukemia after the course of vaccination. An 80% specific lysis of HLA-A2⁺/R3⁺ AML blasts by cytotoxic CD8⁺ T lymphocytes was achieved at a ratio of 5:1 (effector-target cell ratio); 46% of HLA-A2⁺ T2 cells pulsed with R3 peptide were lysed at this E/T ratio. Allogeneic HLA-A2⁻/R3⁺ AML blasts, HLA-A2⁺/R3⁻ AML blasts, as well as HLA-A2⁻/R3⁺ K562 cells were lysed only at background level.