Proteosomal degradation of BCR/ABL protein can generate an HLA-A0301-restricted peptide, but high-avidity T cells recognizing this leukemia-specific antigen were not demonstrated

• Published in: Haematologica (Roma) Vol. 89; no. 9; pp. 1062 - 1071
• Main Authors: Posthuma, EF, van Bergen, CA, Kester, MG, de Paus, RA, van Veelen, PA, de Ru, AH, Drijfhout, JW, Lurvink, EG, Willemze, R, Falkenburg, JH
• Format: Journal Article
• Language: English
• Published: Pavia Haematologica 01-09-2004
• Subjects: Amino Acid Sequence; Antigen Presentation; Antigens, Neoplasm - immunology; Antigens, Neoplasm - metabolism; Biological and medical sciences; Chromosome aberrations; Clone Cells - immunology; Dendritic Cells - immunology; Fusion Proteins, bcr-abl - immunology; Fusion Proteins, bcr-abl - metabolism; Hematologic and hematopoietic diseases; HLA-A Antigens - immunology; HLA-A3 Antigen; HLA-B Antigens - immunology; HLA-B8 Antigen; Humans; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive - immunology; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Mass Spectrometry; Medical genetics; Medical sciences; Molecular Sequence Data; Peptide Fragments - chemical synthesis; Peptide Fragments - immunology; Peptide Fragments - metabolism; Proteasome Endopeptidase Complex - metabolism; Protein Binding; Protein Interaction Mapping; T-Cell Antigen Receptor Specificity; Chromosomal aberration; HLA-System; Peptides; Leukemia; Major histocompatibility system; Degradation; Abnormal chromosome C9; HLA-A-Locus; Immunotherapy; T-Lymphocyte; Abnormal chromosome G22; Class I histocompatibility antigen; Hybrid gene; Chromosome translocation; T-cells; Hematology; BCR/ABL; Enzyme; Transferases; Malignant hemopathy; Philadelphia chromosome; Treatment; Protein kinase; Bcr-abl protein; HLA-A0301; Abnormal chromosome; Avidity
• ISSN: 0390-6078; 1592-8721

Dept. of Hematology, Leiden, University Medical Center, PO Box 9600, 2300 RC, The Netherlands. [e-mail]
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.