Kinetics of the mut-FNDC3B-specific T-cell response in relation to posttransplant course and CD107a degranulation in the presence of tumor cells. (A) (Top) Molecular tumor burden was measured in patient 2 using a patient tumor-specific Taqman PCR assay based on the clonotypic IgH sequence at serial time points before and after HSCT (supplemental Methods). (Middle) Detection of mut-FNDC3B-reactive T cells in comparison with wt-FNDC3B or irrelevant peptides from peripheral blood before and after allo-HSCT by IFN-γ ELISPOT following stimulation with peptide-pulsed autologous B cells. The number of IFN-γ-secreting spots per cells at each time point was measured in triplicate (Welch t test; mut vs wt). (Bottom) Detection of mut-FNDC3B-specific TCR Vβ11 cells by nested clone-specific CDR3 PCR before and after HSCT in peripheral blood of patient 2 (supplemental Methods; supplemental Figure 3). Triangles, time points at which a sample was tested; black, amplification detected, where + indicates detectable amplification up to twofold and ++ indicates more than twofold greater amplification than the median level of all samples with detectable expression of the clone-specific Vβ11 sequence. (B) Evaluation of CD107a expression on 6m/32m mut-FNDC3B-reactive posttransplant CD8⁺ T cells (effectors) in the presence of patient 2 CLL cells or control donor-engrafted normal B cells in patient 2. The numbers indicate the percentage of mut-FNDC3B tetramer-positive cells that are also CD107a positive. For controls (tetramer negative T cells and nonrelated HLA-A*02:01 tumors), please see supplemental Figures 4 and 5.