ABSTRACT
Identification of physiologically relevant peptide vaccine targets calls for the direct analysis of the entirety of naturally presented human leukocyte antigen (HLA) ligands, termed the HLA ligandome. In this study, we implemented this direct approach using immunoprecipitation and mass spectrometry to define acute myeloid leukemia (AML)-associated peptide vaccine targets. Mapping the HLA class I ligandomes of 15 AML patients and 35 healthy controls, more than 25 000 different naturally presented HLA ligands were identified. Target prioritization based on AML exclusivity and high presentation frequency in the AML cohort identified a panel of 132 LiTAAs (ligandome-derived tumor-associated antigens), and 341 corresponding HLA ligands (LiTAPs (ligandome-derived tumor-associated peptides)) represented subset independently in >20% of AML patients. Functional characterization of LiTAPs by interferon-γ ELISPOT (Enzyme-Linked ImmunoSpot) and intracellular cytokine staining confirmed AML-specific CD8(+) T-cell recognition. Of note, our platform identified HLA ligands representing several established AML-associated antigens (e.g. NPM1, MAGED1, PRTN3, MPO, WT1), but found 80% of them to be also represented in healthy control samples. Mapping of HLA class II ligandomes provided additional CD4(+) T-cell epitopes and potentially synergistic embedded HLA ligands, allowing for complementation of a multipeptide vaccine for the immunotherapy of AML.
Subject(s)
Cancer Vaccines/immunology , Histocompatibility Antigens Class II/genetics , Histocompatibility Antigens Class I/genetics , Immunotherapy, Active/methods , Leukemia, Myeloid, Acute/therapy , Neoplasm Proteins/immunology , Peptides/immunology , Amino Acid Sequence , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/metabolism , CD4-Positive T-Lymphocytes/pathology , CD8-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/metabolism , CD8-Positive T-Lymphocytes/pathology , Cancer Vaccines/administration & dosage , Cancer Vaccines/genetics , Case-Control Studies , Epitopes, T-Lymphocyte/chemistry , Epitopes, T-Lymphocyte/genetics , Epitopes, T-Lymphocyte/immunology , Gene Expression , Histocompatibility Antigens Class I/chemistry , Histocompatibility Antigens Class I/immunology , Histocompatibility Antigens Class II/chemistry , Histocompatibility Antigens Class II/immunology , Humans , Immunoprecipitation , Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/immunology , Leukemia, Myeloid, Acute/pathology , Ligands , Mass Spectrometry , Molecular Sequence Data , Neoplasm Proteins/genetics , Nucleophosmin , Peptide Mapping , Peptides/chemistry , Peptides/geneticsABSTRACT
BACKGROUND: Bone-marrow-derived progenitor cells are important in myocardial repair mechanisms following prolonged ischemia. Cell-based therapy of diseased myocardium is limited by a low level of tissue engraftment. OBJECTIVES: The aim of this study was the development of the bifunctional protein αCD133-glycoprotein (GP)VI as an effective treatment for supporting vascular and myocardial repair mechanisms. RESULTS: We have generated and characterized a bifunctional molecule (αCD133-GPVI) that binds both to the subendothelium of the injured microvasculature and to CD133(+) progenitor cells with high affinity. αCD133-GPVI enhances progenitor cell adhesion to extracellular matrix proteins and differentiation into mature endothelial cells. In vivo studies showed that αCD133-GPVI favors adhesion of circulating progenitor cells to the injured vessel wall (intravital microscopy). Also, treatment of mice undergoing experimental myocardial infarction with αCD133-GPVI-labeled progenitor cells reduces infarction size and preserves myocardial function. CONCLUSIONS: The bifunctional trapping protein αCD133-GPVI represents a novel and promising therapeutic option for limiting heart failure of the ischemic myocardium.
