Project description:Cancer somatic mutations can generate neoantigens that distinguish malignant from normal cells. Such neoantigens have been implicated in response to immunotherapies including immune checkpoint blockade, yet their identification and validation remains challenging. Here we discover neoantigens in human mantle cell lymphomas using an integrated strategy for genomic and proteomic tumor antigen discovery that interrogates peptides presented within the tumor major histocompatibility complex (MHC) class I and class II molecules. We applied this approach to systematically identify neoantigen peptides in diagnostic tumor specimens from 17 patients. Remarkably, the 52 discovered neoantigenic peptides were invariably derived from the lymphoma immunoglobulin (Ig) heavy or light chain variable regions. Although we could identify MHC presentation of private germline polymorphic alleles, no mutated peptides were recovered from non-Ig somatically mutated genes. The immunoglobulin variable region somatic mutations were almost exclusively presented by MHC-II. We found T-cells specific for an immunoglobulin-derived neoantigen in the blood of a patient using MHC-II tetramers, and these T-cell clones expanded in frequency following tumor vaccination. These results demonstrate that an integrative approach combining MHC isolation, peptide identification and exome sequencing is an effective platform to uncover tumor neoantigens. Application of this strategy to human lymphoma implicates immunoglobulin neoantigens as targets for lymphoma immunotherapy.
Project description:Cancer somatic mutations can generate neoantigens that distinguish malignant from normal cells. Such neoantigens have been implicated in response to immunotherapies including immune checkpoint blockade, yet their identification and validation remains challenging. Here we discover neoantigens in human mantle cell lymphomas using an integrated strategy for genomic and proteomic tumor antigen discovery that interrogates peptides presented within the tumor major histocompatibility complex (MHC) class I and class II molecules. We applied this approach to systematically identify neoantigen peptides in diagnostic tumor specimens from 17 patients and several cell lines. Remarkably, the discovered neoantigenic peptides were invariably derived from the lymphoma immunoglobulin (Ig) heavy or light chain variable regions. Although we could identify MHC presentation of private germline polymorphic alleles, no mutated peptides were recovered from non-Ig somatically mutated genes. The immunoglobulin variable region somatic mutations were almost exclusively presented by MHC-II. We found T-cells specific for an immunoglobulin-derived neoantigen in the blood of a patient using MHC-II tetramers, and these T-cell clones expanded in frequency following tumor vaccination. These results demonstrate that an integrative approach combining MHC isolation, peptide identification and exome sequencing is an effective platform to uncover tumor neoantigens. Application of this strategy to human lymphoma implicates immunoglobulin neoantigens as targets for lymphoma immunotherapy.
Project description:Expression of stereotyped B cell receptors (BCR), i.e. non-random combinations of immunoglobulin heavy-chain variable (IGHV) genes, complementarity-determining region-3 (HCDR3), and IGV light chains, identifies discrete clusters and represents a peculiar feature of chronic lymphocytic leukemia (CLL). Expression of IGHV3-23 characterized a CLL subset with peculiar molecular and clinical features.
Project description:Immunoglobulin gene rearrangement and somatic hypermutation have the potential to create neoantigens in non-Hodgkin B cell lymphoma. However, the presentation of these putative immunoglobulin neoantigens by B cell lymphomas has not been proven. We used MHC immunoprecipitation followed by liquid chromatography and tandem mass spectrometry (LC-MS/MS) to define antigens presented by follicular lymphomas (FL), chronic lymphocytic leukemias (CLL), diffuse large B cell lymphoma (DLBCL) and mantle cell lymphomas (MCL). We found presentation of the clonal immunoglobulin molecule, including neoantigens by both class I and class II MHC, though more commonly in class II MHC. To determine whether B cell activation could promote presentation of immunoglobulin neoantigens, we used a toll-like receptor 9 (TLR9) agonists to upregulate expression of MHC-II. This resulted in enhanced class II MHC presentation of the immunoglobulin variable region including neoantigens. These findings demonstrate that immunoglobulin neoantigens are presented across most subtypes of B cell lymphomas. Activation of lymphoma cells to upregulate antigen presentation boosts presentation of immunoglobulin neoantigens and represents a strategy for augmenting lymphoma immunotherapies.
Project description:We describe 9 CLL patients who underwent a spontaneous clinical regression. CD38 and ZAP-70 were negative in all cases. Immunoglobulin heavy chain variable region (IgVH) genes, mutated in all 7 evaluable patients, were restricted to the VH3 family in 6, with the usage of VH3-30 gene in 2. The light chain variable region genes were mutated in 6/8 cases, with the usage of Vκ4-1 gene in 3. Microarray analysis of CLL cells revealed a distinctive genomic profile. The number of activated T lymphocytes expressing IFN-γ, TNF-α and IL-4 was similar between CLL in spontaneous regression and healthy individuals.
Project description:The H3.3 histone variant and its chaperone HIRA are involved in active transcription but their detailed roles in regulating somatic hypermutation (SHM) of immunoglobulin variable regions in human B cells is not yet fully understood. In this study we show that, knockout (KO) of HIRA significantly decreased SHM and changed the mutation pattern of the variable region of immunoglobulin heavy chain (IGH) in the human Ramos B cell line without changing the levels of AID and other major proteins known to be involved in SHM. Except for H3K79me2/3, many factors related to active transcription, including H3.3, were substantively decreased in HIRA KO cells and this was accompanied by decreased nascent transcription in IGH locus. The abundance of ZMYND11 that specifically binds to H3.3K36me3 on the Ig locus was also reduced in the HIRA KO. Somewhat surprisingly HIRA loss increased the chromatin accessibility of Ig V region locus. Furthermore, stable expression of ectopic H3.3G34V and H3.3G34R mutants that inhibit both the trimethylation of H3.3K36 and the recruitment of ZMYND11 significantly reduced SHM in Ramos cells, while the H3.3K79M did not. Consistent with HIRA KO, the H3.3G34V mutant also decreased the occupancy of various elongation factors and of ZMYND11 on the IGH variable and downstream switching regions. Our results reveal an unrecognized role of HIRA and the H3.3K36me3 modification in SHM and extend our knowledge of how transcription coupled chromatin structure and accessibility contribute to SHM in human B cells.
Project description:Developing B lymphocytes undergo V(D)J recombination to assemble germline V, D, and J gene segments into exons that encode the antigen-binding variable region of immunoglobulin (Ig) heavy (H) and light (L) chains. IgH and IgL chains associate to form the B cell receptor (BCR), which upon antigen binding activates B cells to secrete BCR as an antibody. Each of the huge number of clonally independent B cells expresses a unique set of IgH and IgL variable regions. Ability of V(D)J recombination to generate vast primary B cell repertoires results from combinatorial assortment of large numbers of different V, D, and J segments, coupled with diversification of the junctions between them to generate the complementary determining region 3 (CDR3) for antigen contact. Approaches to evaluate in depth the content of primary antibody repertoires and, ultimately, to study how they are further molded by secondary mutation and affinity maturation processes are of great importance to the B cell development, vaccine, and antibody fields. We now describe an unbiased, sensitive, and readily accessible assay, referred to as HTGTS repertoire sequencing (HTGTS-Rep-seq), to quantify antibody repertoires. HTGTS-Rep-seq quantitatively identifies the vast majority of IgH and IgL V(D)J exons, including their unique CDR3 sequences, from progenitor and mature mouse B lineage cells via the use of specific J primers. HTGTS-Rep-seq also accurately quantifies DJH intermediates and V(D)J exons in either productive or non-productive configurations. HTGTS-Rep-seq should be useful for studies of human samples, including clonal B-cell expansions and also for following antibody affinity maturation processes. We employed high-throughput genome-wide translocation sequencing adapted repertoire sequencing (HTGTS-Rep-seq) to study antibody repertoires. For HTGTS-Rep-seq libraries, we utilize bait coding ends of J segments to identify, in unbiased fashion, mouse IgH DJH repertoires [processed tlx files] along with both productive and non-productive IgH V(D)J repertoires from both pro-B and peripheral B cells [processed xls files of samples 1-18, 21-51]. Similarly, we also identify mouse productive and non-productive Igk repertoires from peripheral B cells [processed xls files of samples 19,20,52-57].
Project description:The discovery of hepatitis C virus (HCV) in 1989 revealed the virus as the etiology of 40%-90% of the “essential” mixed cryoglobulinemia, where immune complex forms deposit called cryoprecipitate at temperatures below 37 °C. Cryoprecipitate constitutes monoclonal IgM and polyclonal IgG, some of which has reactivity against HCV core and NS3 epitopes. Resultant immune complex is considered entrapped on microvascular endothelium via C1q receptor, leading to complement activation and organ injury presenting predominantly as dermopathy, peripheral neuropathy and nephropathy. However, currently little is known on whether auto-reactive, cold-precipitating IgG components enriched in cryoprecipitate may play some role on the deposition of immune complex and subsequent complement-mediated injury of specific organs. Recently, with the advent of high-throughput immune repertoire sequencing and mass spectrometry, technical feasibility is growing to delineate antibodies of interest and their sequences directly from serum. To date, vast majority of studies actually utilized the antigen column for affinity purification of antibodies of interest, although this strategy is not applicable to disease entity with unknown antigen involvement. In such cases, disease-specific and organ-specific immune deposits may be a good alternative source of etiological antibodies. Herein, targeting HCV cryoglobulinemic vasculitis as a model, we conducted a proof-of-concept study aiming at characterizing the IgG components most prone to cryoprecipitation. To this end, we longitudinally studied one patient with cryoglobulinemic vasculitis with chronic HCV infection. After obtaining informed consent, cryoprecipitate and supernatant were separated from peripheral blood sample. Fab fragments from Protein G-purified IgG were recovered after papain digestion for isobaric tags for relative and absolute quantification (iTRAQ)-based quantitative proteomics. Simultaneously, total RNA was isolated from peripheral blood, and immunoglobulin heavy chain variable region (IGHV) was PCR-amplified with unique molecular identifier (UMI) strategy to construct a personal IGHV sequence library of immunoglobulin variable region. Sequencing output from MiSeq was bioinformatically converted into mass spectrometry database. Search was performed using MaxQuant software.