TY - JOUR AU - EF Posthuma, AU - CA van Bergen, AU - MG Kester, AU - RA de Paus, AU - PA van Veelen, AU - AH de Ru, AU - JW Drijfhout, AU - EG Lurvink, AU - R Willemze, AU - JH Falkenburg, PY - 2004/09/01 Y2 - 2024/03/29 TI - Proteosomal degradation of BCR/ABL protein can generate an HLA-A*0301-restricted peptide, but high-avidity T cells recognizing this leukemia-specific antigen were not demonstrated JF - Haematologica JA - haematol VL - 89 IS - 9 SE - Comparative Studies DO - 10.3324/%x UR - https://haematologica.org/article/view/3217 SP - 1062-1071 AB - BACKGROUND AND OBJECTIVES: Cytotoxic T-lymphocytes (CTL) have been generated in vitro against chronic myeloid leukemia (CML)-associated BCR/ABL-specific peptides. We analyzed the existence of high-avidity T cells recognizing endogenously processed BCR/ABL-specific proteins. DESIGN AND METHODS: We performed binding studies of BCR/ABL-specific peptides, proteosomal digestion of BCR/ABL breakpoint overlapping protein, mass spectrometry of eluates from HLA-*0301-transduced K562 cells, and tried to isolate peptide-specific T-cells using tetramers. RESULTS: We confirmed the binding of the BCR/ABL-specific peptides KQSSKALQR to HLA-A*0301 and GFKQSSKAL to HLA-B*0801. Proteasomal digestion showed cleavage sites leading to KQSSKALQR but not to GFKQSSKAL. Using mass spectrometry KQSSKALQR could not be detected in the eluates from HLA-A*0301-transduced K562 cells. We attempted to induce BCR/ABL-specific CTL lines from 4 healthy donors using dendritic cells pulsed with KQSSKALQR and performed single cell sorting to isolate tetramer-positive T cells. None of 31 generated clones showed BCR/ABL-specific cytotoxicity. Isolation of tetramer-positive cells from peripheral blood of relapsed CML patients after allogeneic transplantation treated with donor lymphocyte infusion resulted in 38 T-cell clones which did not show peptide-specific cytotoxicity. INTERPRETATION AND CONCLUSIONS: We provide evidence that BCR/ABL protein processing can lead to KQSSKALQR peptide binding to HLA-A*0301. However, KQSSKALQR could not be detected in HLA-A*0301-transduced K562 cells, and KQSSKALQR could not be demonstrated to induce high-avidity BCR/ABL-specific CTL. ER -