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  • 1
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    Higher Order Restrictions of the Immunoglobulin Repertoire in CLL: The Illustrative Case of Stereotyped Subsets #2 and #169
    American Society of Hematology ; 2019
    In:  Blood Vol. 134, No. Supplement_1 ( 2019-11-13), p. 5453-5453
    Details
    In: Blood, American Society of Hematology, Vol. 134, No. Supplement_1 ( 2019-11-13), p. 5453-5453
    Abstract: Stereotyped subset #2 (IGHV3-21/IGLV3-21) is the largest subset in CLL (~3% of all patients). Membership in subset #2 is clinically relevant since these patients experience an aggressive disease irrespective of the somatic hypermutation (SHM) status of the clonotypic immunoglobulin heavy variable (IGHV) gene. Low-throughput evidence suggests that stereotyped subset #169, a minor CLL subset (~0.2% of all CLL), resembles subset #2 at the immunogenetic level. More specifically: (i) the clonotypic heavy chain (HC) of subset #169 is encoded by the IGHV3-48 gene which is closely related to the IGHV3-21 gene; (ii) both subsets carry VH CDR3s comprising 9-amino acids (aa) with a conserved aspartic acid (D) at VH CDR3 position 3; (iii) both subsets bear light chains (LC) encoded by the IGLV3-21 gene with a restricted VL CDR3; and, (iv) both subsets have borderline SHM status. Here we comprehensively assessed the ontogenetic relationship between CLL subsets #2 and #169 by analyzing their immunogenetic signatures. Utilizing next-generation sequencing (NGS) we studied the HC and LC gene rearrangements of 6 subset #169 patients and 20 subset #2 cases. In brief, IGHV-IGHD-IGHJ and IGLV-IGLJ gene rearrangements were RT-PCR amplified using subgroup-specific leader primers as well as IGHJ and IGLC primers, respectively. Libraries were sequenced on the MiSeq Illumina instrument. IG sequence annotation was performed with IMGT/HighV-QUEST and metadata analysis conducted using an in-house, validated bioinformatics pipeline. Rearrangements with identical CDR3 aa sequences were herein defined as clonotypes, whereas clonotypes with different aa substitutions within the V-domain were defined as subclones. For the HC analysis of subset #169, we obtained 894,849 productive sequences (mean: 127,836, range: 87,509-208,019). On average, each analyzed sample carried 54 clonotypes (range: 44-68); the dominant clonotype had a mean frequency of 99.1% (range: 98.8-99.2%) and displayed considerable intraclonal heterogeneity with a mean of 2,641 subclones/sample (range: 1,566-6,533). For the LCs of subset #169, we obtained 2,096,728 productive sequences (mean: 299,533, range: 186,637-389,258). LCs carried a higher number of distinct clonotypes/sample compared to their partner HCs (mean: 148, range: 110-205); the dominant clonotype had a mean frequency of 98.1% (range: 97.2-98.6%). Intraclonal heterogeneity was also observed in the LCs, with a mean of 6,325 subclones/sample (range: 4,651-11,444), hence more pronounced than in their partner HCs. Viewing each of the cumulative VH and VL CDR3 sequence datasets as a single entity branching through diversification enabled the identification of common sequences. In particular, 2 VH clonotypes were present in 3/6 cases, while a single VL clonotype was present in all 6 cases, albeit at varying frequencies; interestingly, this VL CDR3 sequence was also detected in all subset #2 cases, underscoring the molecular similarities between the two subsets. Focusing on SHM, the following observations were made: (i) the frequent 3-nucleotide (AGT) deletion evidenced in the VH CDR2 of subset #2 (leading to the deletion of one of 5 consecutive serine residues) was also detected in all subset #169 cases at subclonal level (average: 6% per sample, range: 0.1-10.8%); of note, the 5-serine stretch is also present in the germline VH CDR2 of the IGHV3-48 gene; (ii) the R-to-G substitution at the VL-CL linker, a ubiquitous SHM in subset #2 and previously reported as critical for IG self-association leading to cell autonomous signaling in this subset, was present in all subset #169 samples as a clonal event with a mean frequency of 98.3%; and, finally, (iii) the S-to-G substitution at position 6 of the VL CDR3, present in all subset #2 cases (mean : 44.2% ,range: 6.3-87%), was also found in all #169 samples, representing a clonal event in 1 case (97.2% of all clonotypes) and a subclonal event in the remaining 5 cases (mean: 0.6%, range: 0.4-1.1%). In conclusion, the present high-throughput sequencing data cements the immunogenetic relatedness of CLL stereotyped subsets #2 and #169, further highlighting the role of antigen selection throughout their natural history. These findings also argue for a similar pathophysiology for these subsets that could also be reflected in a similar clonal behavior, with implications for risk stratification. Disclosures Sutton: Abbvie: Honoraria; Gilead: Honoraria; Janssen: Honoraria. Stamatopoulos:Abbvie: Honoraria, Research Funding; Janssen: Honoraria, Research Funding. Chatzidimitriou:Janssen: Honoraria.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood-2019-128017
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2019
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  • 2
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    VH CDR3-Focused Somatic Hypermutation in CLL IGHV-IGHD-IGHJ Gene Rearrangements with 100% IGHV Germline Identity
    American Society of Hematology ; 2019
    In:  Blood Vol. 134, No. Supplement_1 ( 2019-11-13), p. 4277-4277
    Details
    In: Blood, American Society of Hematology, Vol. 134, No. Supplement_1 ( 2019-11-13), p. 4277-4277
    Abstract: Classification of patients with chronic lymphocytic leukemia (CLL) based on the immunoglobulin heavy variable (IGHV) gene somatic hypermutation (SHM) status has established predictive and prognostic relevance. The SHM status is assessed based on the number of mutations within the sequence of the rearranged IGHV gene excluding the VH CDR3. This is mostly due to the difficulty in discriminating actual SHM from random nucleotides added between the recombined IGHV, IGHD and IGHJ genes. Hence, this approach may underestimate the true impact of SHM, in fact overlooking the most critical region for antigen-antibody interactions i.e. the VH CDR3. Relevant to mention in this respect, studies from our group in CLL with mutated IGHV genes (M-CLL), particularly subset #4, have revealed considerable intra-VH CDR3 diversity attributed to ongoing SHM. Prompted by these findings, here we investigated whether SHM may also be present in cases bearing 'truly unmutated' IGHV genes (i.e. 100% germline identity across VH FR1-VH FR3), focusing on two well characterized stereotyped subsets i.e. subset #1 (IGHV clan I/IGHD6-19/IGHJ4) and subset #6 (IGHV1-69/IGHD3-16/IGHJ3). These subsets carry germline-encoded amino acid (aa) motifs within the VH CDR3, namely QWL and YDYVWGSY, originating from the IGHD6-19 and IGHD3-16 gene, respectively. However, in both subsets, cases exist with variations in these motifs that could potentially represent SHM. The present study included 12 subset #1 and 5 subset #6 patients with clonotypic IGHV genes lacking any SHM (100% germline identity). IGHV-IGHD-IGHJ gene rearrangements were RT-PCR amplified by subgroup-specific leader primers and a high-fidelity polymerase in order to ensure high data quality. RT-PCR products were subjected to paired-end NGS on the MiSeq platform. Sequence annotation was performed with IMGT/HighV-QUEST and metadata analysis was undertaken using an in-house purpose-built bioinformatics pipeline. Rearrangements with the same IGHV gene and identical VH CDR3 aa sequences were defined as clonotypes. Overall, we obtained 1,570,668 productive reads with V-region identity 99-100%; of these, 1,232,958 (mean: 102,746, range: 20,796-242,519) concerned subset #1 while 337,710 (mean: 67,542, range: 50,403-79,683) concerned subset #6. On average, 64.4% (range: 1.7-77.5%) of subset #1 reads and 49.2% (range: 0.7-70%) of subset #6 reads corresponded to rearrangements with IGHV genes lacking any SHM (100% germline identity). Clonotype computation revealed 1,831 and 1,048 unique clonotypes for subset #1 and #6, respectively. Subset #1 displayed a mean of 157 distinct clonotypes per sample (range: 74-267), with the dominant clonotype having a mean frequency of 96.9% (range: 96-98.2%). Of note, 44 clonotypes were shared between different patients (albeit at varying frequencies), including the dominant clonotype of 11/12 cases, which was present in 2-6 additional subset #1 patients. Subset #6 cases carried a higher number of distinct clonotypes per sample (mean: 219, range: 189-243) while the dominant clonotype had a mean frequency of 95.6% (range: 94.5-96.5%). Shared clonotypes (n=30) were identified also in subset #6 and the dominant clonotype of each subset #6 case was present in 3-5 additional subset #6 patients. Focusing on the VH CDR3, in particular the IGHD-encoded part, the following observations were made: (1) in both subsets, extensive intra-VH CDR3 variation was detected at certain positions within the IGHD gene; (2) in most cases, the observed aa substitutions were conservative i.e. concerned aa sharing similar physicochemical properties. Particularly noteworthy in this respect were the observations in subset #6 that: (i) the valine residue (V) in the D-derived YDYVWGSY motif was very frequently mutated to another aliphatic residue (A, I, L); (ii) in cases were the predominant clonotype carried I (also in the Sanger-derived sequence), several minor clonotypes carried the germline-encoded V, compelling evidence that the observed substitution concerned true SHM. In conclusion, we provide immunogenetic evidence for intra-VH CDR3 variations, very likely attributed to SHM, in CLL patients carrying 'truly unmutated' IGHV genes. While the prognostic/predictive relevance of this observation is beyond the scope of the present work, our findings highlight the possible need to reappraise definitions ('semantics') regarding SHM status in CLL. Disclosures Stamatopoulos: Janssen: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding. Chatzidimitriou:Janssen: Honoraria.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood-2019-127979
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2019
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  • 3
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    Longitudinal High-Throughput T Cell Repertoire Profiling of Chronic Lymphocytic Leukemia Patients Under Different Types of Treatment: Implications for Combination Strategies
    American Society of Hematology ; 2018
    In:  Blood Vol. 132, No. Supplement 1 ( 2018-11-29), p. 4400-4400
    Details
    In: Blood, American Society of Hematology, Vol. 132, No. Supplement 1 ( 2018-11-29), p. 4400-4400
    Abstract: Using next-generation sequencing (NGS), we recently documented the clonal architecture of the T cell repertoire in treatment-naive chronic lymphocytic leukemia (CLL), with ample immunogenetic evidence indicating selection by restricted antigens. Our preliminary NGS study in 16 patients pre- and 3-month post-treatment indicated a differential impact of standard chemoimmunotherapy (FCR) versus B cell receptor signaling inhibitors (BcRi) on CLL T cells. Prompted by these observations, here we sought to comprehensively assess CLL T cell repertoire changes over treatment in relation to both treatment type and clinical response by combining NGS immunoprofiling, flow cytometry and functional assays. NGS profiling of the T cell receptor (TR) gene repertoire was performed in 28 CLL patients who received FCR (n=9), ibrutinib (IB, n=15) and/or rituximab-idelalisib (R-ID, n=10) at successive timepoints (pre, +3mo, +9mo and at deepest clinical response, total samples: n=113). TRBV-TRBD-TRBJ gene rearrangements were RT-PCR amplified and subjected to paired-end NGS. Raw reads were processed through a purpose-built, validated bioinformatics pipeline, culminating to 20,347,768 productive, filtered-in TRB sequences (median 155,479/sample). For repertoire analysis, clonotypes (i.e. rearrangements with identical TRBV gene usage and amino acid complementarity-determining region 3 sequence) were considered (median 11,420 distinct clonotypes/sample). All cases displayed significant clonal T cell expansions both pre- and post-treatment [median clonality, measured as the cumulative frequency of the 10 most expanded (major) clonotypes/sample: 30.3% and 39.6%, respectively]. Median clonality significantly increased at +3mo in the FCR (29.0% to 46.9%, p 〈 .001) and R-ID group (33.0% to 39.1%, p 〈 .001), but not in the IB group (33.3% to 31.2%, p 〉 .05). Overtime analysis revealed a gradual increase of clonality over deepening clinical response (pre-, +3mo, +9mo, deepest response) in the R-ID group (33.0% to 39.1% to 46.0% to 46.1%, respectively; p 〈 .001), but only a trend in this respect for IB (33.3% to 31.2% to 33.8% to 42.0%; p 〉 .05). Considering that FCR resulted in T cell repertoire reconstitution whereas BcRis retained pre-treatment clones, we then focused on major clones persisting over treatment and found that they significantly expanded in the R-ID group, peaking at +3mo (p 〈 .01). Cross-comparison across all CLL patients and against 767,438 unique TRB sequences retrieved from multiple public databases (HSV infections, T-cell lymphoproliferations, autoimmune disorders, healthy individuals), revealed 23/563 major clonotypes shared exclusively among CLL patients, alluding to selection by conserved CLL-related antigens. We then sought to test the functional effect of treatments on T cells. To this end, we evaluated activation markers on CLL T cell subpopulations for 8 CLL patients (R-ID, n=4; IB, n=4) pre- and +3mo post-treatment by flow cytometry and found statistically significant upregulation of T cell activation markers for R-ID compared to IB, particularly for: (i) CD69 in CD4+ effector memory T cells (p 〈 .01); (ii) CD25 in CD8+ TEMRA T cells (p=0.006); and, (iii) CD38 in CD8+ effector memory T cells (p 〈 .05) and CD8+ TEMRA T cells (p 〈 .05). We also investigated the ability of CD3+ T cells, purified from 13 patients pre- and +3mo post-treatment (FCR, n=3; R-ID, n=5; IB, n=5), to form immune synapses with autologous pre-treatment CD19+ tumor cells. Quantitative relative recruitment index (RRI) analysis for F-actin showed that both R-ID (p 〈 .01) and IB (p 〈 .05) treated T cells form polarized immune synapses in contrast to FCR (p 〉 .05). Taken together, NGS immunoprofiling suggests that BcRis retain T cell clones that may have developed in response to CLL-related antigens, which in the case of R-ID expand and peak at +3mo. Phenotypic and immune synapse bioassays support a concurrent restoration of functionality, mostly evident for R-ID, arguably contributing to clinical response. Overall, this data provides rationale for designing combination strategies, e.g. of R-ID with immunomodulating drugs, aiming to boost cytotoxic anti-tumor responses. Moreover, identifying the relevant neoepitopes may eventually pave the way for stratified treatments by means of engineered T cells or peptide vaccines, especially if these epitopes are conserved among CLL. Disclosures Vardi: Janssen: Honoraria; Gilead: Research Funding. Gemenetzi:Gilead: Research Funding. Ramsay:MedImmune: Research Funding; Roche Glycart AG: Research Funding; Celgene Corporation: Research Funding. Stamatopoulos:Janssen: Honoraria, Research Funding; Gilead: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding. Hadzidimitriou:Abbvie: Research Funding; Gilead: Research Funding; Janssen: Honoraria, Research Funding.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood-2018-99-118006
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2018
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 4
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    High-Throughput T Cell Receptor (TR) Repertoire Analysis of Virus-Specific T Cells: Implications for T Cell Immunotherapy and Viral Infection Risk Stratification
    American Society of Hematology ; 2018
    In:  Blood Vol. 132, No. Supplement 1 ( 2018-11-29), p. 2057-2057
    Details
    In: Blood, American Society of Hematology, Vol. 132, No. Supplement 1 ( 2018-11-29), p. 2057-2057
    Abstract: Viral infections, mainly by cytomegalovirus (CMV), Epstein Barr virus (EBV) and polyomavirus type I (BKV), are major causes of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). As effective immune responses against human viruses rely on an armamentarium of T-cell receptor (TR) repertoire capable of recognizing a broad range of antigenic peptides of those pathogens, reconstitution of antiviral immunity, either by spontaneous generation of endogenous virus-specific T cells (VSTs) or by adoptive immunotherapy with VSTs, plays a critical role to fight infections. We here evaluated the diversity and clonality of TR repertoire of functional tri-virus-specific T cell products generated from immunocompetent donors (n=10) and compared their TR gene repertoire to that of peripheral blood mononuclear cells (PBMCs) from patients who had undergone allo-HSCT (n=5). To generate tri-VSTs, PBMCs derived from 15-20ml of peripheral blood of normal donors, were exposed to EBV, CMV and BKV overlapping peptides and cultured in the presence of interleukin 4 (IL-4) and IL-7 for 10 days in G-rex bioreactors. Specificity of donor-derived VSTs and patient-derived PBMCs was measured by IFN-γElispot. TR diversity was investigated by next-generation sequencing on a MiSeq Sequencer, after amplification of TR beta chain gene rearrangements by RT-PCR with the BIOMED-2 protocol. Raw NGS reads were filtered based on their length and quality and the filtered-in sequences were submitted to IMGT/HighVQUEST. Metadata analysis and clonotype computation were performed using a validated in-house bioinformatics platform. As clonotype we defined sequences carrying the same TRBV gene and identical CDR3 amino acid sequence. Tri-VSTs provided 947,298 productive TRBV-TRBD-TRBJ rearrangements and a polyclonal and highly diverse TR gene repertoire, consisting of a total of 169,502 unique clonotypes (average: 16,950/sample, range 4,057-45,602), 64,971 (38.3%) of which were expanded (corresponding to more than one sequence). In terms of clonality, the mean relative frequency of the major clonotype in all tri-VSTs was 12.6% (range 3.3-29.2%). Interestingly, among tri-VST cell lines, 637 clonotypes were shared (present in 〉 2/10 samples), 80 were highly shared (present in 〉 3/10 samples) while 7 were present in 6-8 different VST lines and largely expanded, accounting for up to 29.2% of all sequences. Importantly, there were 65 of 96 major VST clonotypes shared, thus suggesting that they were potentially associated with recognition of the targeted viruses. Given that 4/10 VSTs cell lines were not specific for CMV, while being EBV-and BKV-specific, dominant TRs in those 4 cell lines can potentially be associated with EBV- or BKV-activity. By searching a public database of TR clonotypes with known reactivity against EBV and/or CMV (ShugayM, Nucleic Acids Research, 2018), we found 8 shared EBV-specific and 4 shared CMV-specific clonotypes among our VSTs and the 499 public clonotypes. When we compared the produced VSTs with PBMCs from 3 allo-grafted patients with circulating CMV-, BKV- and EBV-specific T cells and previous viral reactivation, we detected 163 shared clonotypes. Likewise, we observed 21 and 23 shared clonotypes in similar frequencies, between VSTs and PBMCs from 2 patients with CMV- or BKV-specific T cell immunity. These data identify clones that potentially expand in vivo and protect patients from viral infections. Overall, our findings reveal high levels of TR clonality in cell lines enriched for T cells reactive against EBV and/or CMV and/or BKV and provide insights into the TR repertoire of ex vivo- or endogenously-generated VSTs. Our approach may help to identify optimal TRs for immunotherapy as well as TRs which can be used as a tool for risk stratification of viral infections. Disclosures Agathangelidis: Gilead: Research Funding. Gemenetzi:Gilead: Research Funding. Stamatopoulos:Abbvie: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria, Research Funding. Hadzidimitriou:Gilead: Research Funding; Abbvie: Research Funding; Janssen: Honoraria, Research Funding.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood-2018-99-118851
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2018
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 5
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    Higher-order immunoglobulin repertoire restrictions in CLL: the illustrative case of stereotyped subsets 2 and 169
    American Society of Hematology ; 2021
    In:  Blood Vol. 137, No. 14 ( 2021-04-8), p. 1895-1904
    Details
    In: Blood, American Society of Hematology, Vol. 137, No. 14 ( 2021-04-8), p. 1895-1904
    Abstract: Chronic lymphocytic leukemia (CLL) major stereotyped subset 2 (IGHV3-21/IGLV3-21, ∼2.5% of all cases of CLL) is an aggressive disease variant, irrespective of the somatic hypermutation (SHM) status of the clonotypic IGHV gene. Minor stereotyped subset 169 (IGHV3-48/IGLV3-21, ∼0.2% of all cases of CLL) is related to subset 2, as it displays a highly similar variable antigen-binding site. We further explored this relationship through next-generation sequencing and crystallographic analysis of the clonotypic B-cell receptor immunoglobulin. Branching evolution of the predominant clonotype through intraclonal diversification in the context of ongoing SHM was evident in both heavy and light chain genes of both subsets. Molecular similarities between the 2 subsets were highlighted by the finding of shared SHMs within both the heavy and light chain genes in all analyzed cases at either the clonal or subclonal level. Particularly noteworthy in this respect was a ubiquitous SHM at the linker region between the variable and the constant domain of the IGLV3-21 light chains, previously reported as critical for immunoglobulin homotypic interactions underlying cell-autonomous signaling capacity. Notably, crystallographic analysis revealed that the IGLV3-21–bearing CLL subset 169 immunoglobulin retains the same geometry and contact residues for the homotypic intermolecular interaction observed in subset 2, including the SHM at the linker region, and, from a molecular standpoint, belong to a common structural mode of autologous recognition. Collectively, our findings document that stereotyped subsets 2 and 169 are very closely related, displaying shared immunoglobulin features that can be explained only in the context of shared functional selection.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood.2020005216
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2021
    detail.hit.zdb_id: 1468538-3
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  • 6
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    Chystallographic Evidence of Autologous Recognition By a Clonotypic B Cell Receptor in Chronic Lymphocytic Leukemia
    American Society of Hematology ; 2015
    In:  Blood Vol. 126, No. 23 ( 2015-12-03), p. 4129-4129
    Details
    In: Blood, American Society of Hematology, Vol. 126, No. 23 ( 2015-12-03), p. 4129-4129
    Abstract: Chronic lymphocytic leukemia (CLL) leukemic cells express B-cell receptor immunoglobulin (BcR IG) whose signaling is of paramount importance throughout the natural history of the disease. Indeed, signaling pathways downstream of the BcR are constitutively active in all cases of CLL and inhibitors of the Bruton's tyrosine kinase BTK (Ibrutinib) or PI3Kδ (Idelalisib), two downstream signaling effectors, are clinically effective. This functional evidence complements earlier molecular observations supporting antigen drive in CLL ontogeny, including the distinction of CLL into cases with somatically hypermutated BcR IG (M-CLL) that have a significantly better outcome compared to those with unmutated, germline-like receptors (U-CLL). CLL also displays a remarkably skewed BcR IG gene repertoire, culminating in the existence of highly homologous, stereotyped BcR IG in 〉 30% of cases, indicating selection by a limited set of antigenis. A number of potential antigenic elements have been described, being recognized by the monoclonal receptors and able to deliver intracellular signals. More recently, it has been reported that CLL cells are endowed with the apparently unique property of autonomous signaling, since individual CLL-derived BcR IG can promote Ca2+ influx and NF-κB target gene transcription in a reconstituted B cell system upon self-recognition of common BcR-intrinsic epitopes. However, the precise molecular details of such process are unknown. In order to gain insight into the molecular interactions, particularly to further understand the role played by autonomous signaling, we determined the crystal structures of two BcR IG of CLL cases assigned to subset #4. This is a CLL subset expressing stereotyped, G(κ)-switched BcR IG encoded by the IGHV4-34/IGKV2-30 gene combination. Subset #4 accounts for ~1% of all CLL and is the largest within M-CLL, distinctive for a particularly indolent clinical course. BcR IG derived from two subset #4 cases were found to bind autologously via their VH CDR3 loops to a composite surface spanning the variable and constant regions of the heavy chain; the relevant epitope is conserved in all cases belonging to subset #4 and differs from other non-subset #4 BcR IG. This specific self-recognition was identified as dependent on the individual IG gene usage in the BcR, and is functionally relevant as it occurs in solution and leads to intracellular signalling in B cells. Analysis of epitope and paratope mutants revealed that the interactions observed in the crystal structures are mediated by a few critical amino acid residues. Indeed, the distinctively conserved amino acid residues in the VH CDR3 loop of the BcR IG both dictate a specific VH-VK pairing and shape the combining site for autologous recognition. Moreover, the epitope comprises specific amino acids from the CH1 domain that restrict the autologous recognition to IgG molecules. Finally, we found persisting long-lived interaction occurring between subset #4 BcR IGs, thus recalling high affinity receptor-cognate antigen interactions associated with the induction of anergy. This scenario well fits with the anergic phenotype of the subset #4 leukemic cells, and thus provides a biochemical explanation for the indolent clinical course of this subset. In conclusion, though focusing on a particular CLL subset, the structural and biochemical analysis here presented describes a general model for autologous recognition that may epitomize the molecular events leading to the expansion of CLL B lymphocytes at large. It is conceivable that CLL-associated BcR IGs can each bind to a distinct internal epitope with the specific nature of the interaction dictated by diverse factors e.g. VDJ recombination, heavy and light chain pairing, SHM, and isotype switch. The strength and persistence of the autologous recognition can then lead to a specific outcome in the intracellular signaling process, ranging from proliferation to anergy. The structural diversity thus produced in the BcR IG development may be linked to and underlie the heterogeneity characterizing CLL at the biological and clinical level. Disclosures Stamatopoulos: Gilead Sciences: Research Funding; Janssen Pharmaceuticals: Research Funding. Ghia:Pharmacyclics: Honoraria; Gilead: Honoraria, Research Funding, Speakers Bureau; Janssen: Honoraria; Roche: Research Funding; GSK: Research Funding; AbbVie: Honoraria; Celgene: Honoraria; Adaptive Biotechnologies: Consultancy.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood.V126.23.4129.4129
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2015
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  • 7
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    The Immunoglobulin Gene Repertoire of Low-Count CLL-Like MBL Is Different from CLL: Diagnostic Considerations and Implications for Clinical Monitoring
    American Society of Hematology ; 2008
    In:  Blood Vol. 112, No. 11 ( 2008-11-16), p. 779-779
    Details
    In: Blood, American Society of Hematology, Vol. 112, No. 11 ( 2008-11-16), p. 779-779
    Abstract: The term Monoclonal B Lymphocytosis (MBL) defines the presence of Monoclonal B Lymphocytes in the blood of otherwise healthy individuals. Though phenotypically heterogeneous, most MBL cases resemble CLL cells (CD5+, CD20dim, CD79b dim, sIgdim). The interest in MBL increased after this entity was included in the revised NCI-WG/IWCLL guidelines for the diagnosis and management of CLL (Hallek et al, 2008) and defined as “the presence of fewer than 5×109/L B lymphocytes” in the peripheral blood. However, the concentration of MBL in the blood of any given individual is extremely variable accounting in some cases for the vast majority of circulating B cells while being a negligible portion of them in others. It is then plausible that molecular differences could exist between low- vs. high-count MBL, being the latter likely more advanced on the way to become CLL. In this context, it was recently reported that subjects with 〈 5×109/L CLL-like MBL but with lymphocytosis will require treatment at a rate of 1.1% per year. The absolute B-cell count turned out to be the only independent prognostic factor associated with progressive lymphocytosis, as all MBL cases studied had immunoglobulin (IG) gene features and cytogenetic abnormalities similar to good prognosis CLL. In contrast, very little is known about low-count MBL cases accidentally found in the general population. By cytofluorograph analysis, we identified 89 CLL-like MBL in the blood of 1725 healthy individuals 〉 18 years old (5.1%) and analyzed the IGHV-D-J rearrangements expressed by 51 of them, the majority being characterized by few clonal B cells (mean 6.9% of circulating B lymphocytes, with only 13 cases 〉 10%). CLL-like MBL cells showed a predominance of IGHV3 genes, followed by IGHV4 genes, resembling the normal repertoire. The most frequent IGHV gene in MBL was IGHV4- 59/61, rarely used in CLL. The MBL repertoire was also conspicuous for the lack of the IGHV1-69 gene (the predominant gene in unmutated CLL, ~25%) and the low frequency of the IGHV4-34 gene (2/51 sequences, 3.9%), the most frequent gene in mutated CLL (~12%). Following the 98% identity cut-off value, 36/51 sequences (70.5%) were defined as “mutated”, whereas the remainder had “unmutated” IGHV genes. Alignment of MBL HCDR3 sequences to a comprehensive panel of CLL HCDR3 sequences identified 2/51 (3.9%) MBL cases with a sequence similar to previously described CLL cases (“stereotyped receptors”). These results show that the IG gene repertoire in low-count MBL, accidentally found in the general population, does not show the typical CLL-related biases in terms of IGHV gene usage. This cannot be simply explained by the higher number of mutated cases among MBL, as unmutated cases account for almost a third of CLL-like MBL, indicating a molecular heterogeneity. In addition, HCDR3 stereotypy in MBL is significantly less frequent than in CLL ( 〉 25% of cases). Occasional MBL may indeed express a CLL “stereotyped receptor”, implying that the potential to evolve into a leukemia exists within MBL, though at low frequency, and may depend on precise selection mechanisms based on the molecular features of the B cell receptor. Taken together, our results strongly suggest that the detection of MBL in an otherwise healthy subject is not always equivalent to a pre-leukemic state. Differential IG molecular features might provide a better tool to discriminate individuals at risk of progression than an arbitrary mathematical threshold. Detailed IG molecular analysis of individual MBL may help to identify those few cases that necessitate continuous clinical monitoring to anticipate disease progression and, on the other hand, to avoid the burden of lengthy and expensive follow-ups in the vast number of persons who are extremely unlikely to develop CLL, though carrying MBL in their blood.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood.V112.11.779.779
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2008
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  • 8
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    Genome-Wide Array-Based Methylation Profiling Reveals Preferential Methylation of Homeobox Transcription Factor Genes In Mantle Cell Lymphoma and Pro-Apoptotic Genes In Chronic Lymphocytic Leukemia
    American Society of Hematology ; 2010
    In:  Blood Vol. 116, No. 21 ( 2010-11-19), p. 536-536
    Details
    In: Blood, American Society of Hematology, Vol. 116, No. 21 ( 2010-11-19), p. 536-536
    Abstract: Abstract 536 Introduction: Mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL) are B-cell malignancies of different postulated origin, genetics, clinical presentation and prognosis. Several studies have reported that both MCL and CLL individually exhibit aberrant methylation in comparison to normal B-cells. However, a comprehensive comparison of the methylation profiles of these two B-cell disorders has not been performed yet. This strategy has the potential to identify cellular pathways and genes that are specifically targeted in each disease. Methods: We applied the genome-wide Illumina Infinium HumanMethylation27 BeadChip array (Illumina, San Diego, USA) which measures methylation levels at 27,578 CpG dinucleotides covering 14,495 genes, to compare the methylation profiles in: (i) 20 MCL cases; and, (ii) 30 CLL cases, 15 each with unmutated stereotyped subset #1 (IGHV1-5-7/IGKV1(D)-39) B cell receptors (BCRs) or mutated stereotyped subset #4 (IGHV4-34/IGKV2-30) BCRs, where these two subsets represent prototypes of unmutated and mutated CLL. The methylation status for each detected CpG site ranged between 0.1 (completely unmethylated) to 1 (completely methylated). Results: As expected, major differences in methylation patterns between MCL and CLL were observed. When the methylation profiles of the two entities were compared, 51 genes were identified as differentially methylated in all comparisons (MCL versus both CLL subsets combined and each subset separately). Among the 19 genes highly methylated in MCL were six (32%) homeobox or homeodomain-containing transcription factors (e.g. POU4F1, PITX3), whereas genes enhancing cell proliferation and tumor progression such as MERTK and CAMP were hypomethylated in MCL. Of the 32 genes hypermethylated in CLL were six pro-apoptotic genes, including DYRK2 and CYFIP2, the tumor suppressor PRDM2 and the cell cycle regulator CCND1. Conclusions: We report for the first time disease-biased methylation profiles for different functional classes of genes in MCL or CLL. Homeobox genes were highly methylated in MCL, whereas CLL was characterized by methylation of apoptosis-related genes. The identified differences in global methylation profiles between MCL and CLL may assist in unfolding distinct epigenetic silencing mechanisms involved in the pathogenesis of these B-cell malignancies. Disclosures: No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood.V116.21.536.536
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2010
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  • 9
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    EGR2 Mutations in Chronic Lymphocytic Leukemia: A New Bad Player
    American Society of Hematology ; 2015
    In:  Blood Vol. 126, No. 23 ( 2015-12-03), p. 4126-4126
    Details
    In: Blood, American Society of Hematology, Vol. 126, No. 23 ( 2015-12-03), p. 4126-4126
    Abstract: *Contributed equally as first authors. **Contributed equally as senior authors. Recurrent mutations within EGR2, a versatile transcription factor involved in differentiation of hematopoietic cells, were recently reported in 8% of advanced-stage chronic lymphocytic leukemia (CLL) patients, where they appear to be associated with a worse outcome. EGR2 is activated through ERK phosphorylation upon B-cell receptor (BcR) stimulation, and we have previously shown that EGR2 -mutated CLL patients display altered expression of EGR2 down-stream target genes compared to wildtype (wt) patients, thereby pointing to a pathogenic role for EGR2 mutations in dysregulating BcR signaling. To gain further insight into the incidence and prognostic impact of EGR2 mutations in CLL, we screened samples from a well-characterized series of 1430 patients, either by Sanger sequencing (n=1019) or targeted deep-sequencing (n=370), both covering the recently reported EGR2 hotspot in exon 2. In addition, whole-exome data was available for an additional 43 patients. Different cohorts were included in our analysis ranging from 'general practice' CLL (33% IGHV-unmutated (U-CLL), 6% TP53 -aberrant (TP53abn), n=693), to adverse-prognostic CLL (89% U-CLL, 26% TP53abn, n=325), patients belonging to clinically aggressive stereotyped subsets #1-3 & #5-8 (n=342), patients relapsing after FCR therapy (n=41) and Richter transformed cases (n=31), thus reflecting the heterogeneous nature of CLL. Nineteen EGR2 mutations were detected by Sanger sequencing, while 22 additional mutations were identified with deep-sequencing using a 5% variant allele frequency (VAF) cutoff (median 39%, range 5.6-63.9%, median coverage 43,000X). With the exception of one in-frame deletion, all mutations were missense alterations located within the three zinc-finger domains. Significant enrichment of EGR2 mutations was observed in adverse-prognostic (18/325, 5.5%) and FCR-relapsing (4/41, 9.8%) CLL compared to the 'general practice' cohort (18/693, 2.6%, Figure 1A). A surprisingly low frequency was observed among clinically aggressive stereotyped subsets (5/342, 1.5%), although the cause for this observation is currently unknown. Finally, 2/31 (6.5%) cases with Richter transformation carried an EGR2 mutation. Of the 4 FCR-relapsing, EGR2 -mutated cases with available overtime samples, all demonstrated a significant expansion of the EGR2 -mutated clone at relapse (VAF-increase between 15-41%). In addition, subclonal levels of EGR2 hotspot mutations (VAF 0.5-5%) were detected in an additional 13/370 (3.5%) cases by deep-sequencing. The majority of EGR2 -mutated CLL patients (32/39, 82%) concerned U-CLL and the following aberrations co-occurred: 11q-deletions (n=10), TP53abn (n=6), NOTCH1 (n=3)or SF3B1 (n=3) mutations. EGR2 -mutated patients displayed a significantly worse overall survival compared to wt patients (median survival 59 vs. 141 months, p=0.003, using a conservative 10% VAF cutoff), and a poor outcome similar to cases with TP53abn (Figure 1B). In multivariate analysis (n=583), EGR2 status remained an independent factor (p=0.038), along with stage (p=0.048) and IGHV status (p 〈 0.0001), while TP53abn and del(11q) showed borderline significant values (p=0.069 and p=0.059, respectively). To investigate the impact of EGR2 mutations in a homogeneously treated patient cohort, EGR2 mutation analysis of the UK CLL4 trial is underway. To date, 8/247 patients have been identified as EGR2 -mutated by deep-sequencing and they show a decrease of their median overall survival (42 vs. 77 months) compared to wt patients; however, this did not reach statistical significance, probably due to the low number of EGR2 -mutated cases. Final results of the UK CLL4 trial will be presented at the ASH meeting. In summary, EGR2 -mutant cases appear to constitute a novel poor-prognostic subgroup of CLL, with mutations occurring either as disease-initiating aberrations, i.e. in cases where mutations were found in the entire clone, or as subclonal driver events linked to progressive disease. The latter is reflected by the enrichment of EGR2 mutations in aggressive CLL and the association of EGR2 mutations with an overall dismal prognosis. Considering the potential role of mutated EGR2 in altering BcR signaling, it will be particularly relevant to study the efficacy of BcR inhibitors in this patient group. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Langerak: Roche: Other: Lab services in the field of MRD diagnostics provided by Dept of Immunology, Erasmus MC (Rotterdam); InVivoScribe: Patents & Royalties: Licensing of IP and Patent on BIOMED-2-based methods for PCR-based Clonality Diagnostics.; DAKO: Patents & Royalties: Licensing of IP and Patent on Split-Signal FISH. Royalties for Dept. of Immunology, Erasmus MC, Rotterdam, NL. Schuh:Acerta Pharma BV: Research Funding. Strefford:Roche: Research Funding.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood.V126.23.4126.4126
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2015
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  • 10
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    Late Onset Neutropenia Develops Selectively in Only a Subset of Patients with T Large Granular Lymphocyte Proliferation After Rituximab Treatment for Lymphoma,
    American Society of Hematology ; 2011
    In:  Blood Vol. 118, No. 21 ( 2011-11-18), p. 3675-3675
    Details
    In: Blood, American Society of Hematology, Vol. 118, No. 21 ( 2011-11-18), p. 3675-3675
    Abstract: Abstract 3675 Emerging evidence suggests that B cells can actively modulate T cell immune responses by presenting antigen, providing co-stimulation and secreting cytokines. This has prompted investigation whether B cell depletion by monoclonal antibodies, including Rituximab, can alter the subset composition, activation or function of T cells. Rituximab-associated late onset neutropenia (R-LON) is increasingly recognized as a long-term adverse event of Rituximab. Although the etiology of R-LON is not fully elucidated, the syndrome seems to be multifactorial and likely caused by immune-mediated mechanisms. We have previously shown that at least a proportion of R-LON may develop in a setting of expanded cytotoxic T cell populations in peripheral blood (PB) with a large granular lymphocyte (LGL) phenotype (CD3+CD8+CD57+). Here, we extend our observations regarding PB lymphocyte subset composition in a cohort of 107 Rituximab-treated patients with available results from PB flow cytometry analysis performed at roughly similar intervals after the initial Rituximab administration. The present cohort included 107 patients, aged 16–83 (median 60), who received Rituximab for the treatment of chronic lymphocytic leukemia (CLL) (29), diffuse large B cell lymhoma (DLBCL) (20), marginal zone lymphomas (15), follicular lymhoma (FL) (15), mantle cell lymphoma (MCL) (8) and auto-immune cytopenias (20). Overall, we found: (i) increased ( 〉 1.0×109/l) CD8+ cells in 45/107 (42%) cases; (ii) CD4+/CD8+ cell ratios 〈 0.7 in 56/107 (52%) cases; and, (iii) T-LGLs 〉 20% in 66/107 (63%) cases. Within this cohort, 33 cases (group A) developed R-LON, whereas the remainder (group B, n=74) did not develop this syndrome over a comparable observation period. Importantly, no patient with autoimmune cytopenia developed R-LON. R-LON was significantly more frequent in patients with lymphoma subtypes treated with intensive chemotherapy (CLL, DLBCL, MCL), as well as patients who underwent autologous transplantation (p\q0.001 for all comparisons). No significant differences were noted between groups A or B regarding PB lymphocyte subset composition. We next evaluated the findings from the histopathological study of bone marrow biopsy samples, available in 17 Group A and 19 Group B cases, all with a diagnosis of lymphoma. The morphological and immunohistochemical examination revealed a series of features common in both groups, summarized as follows: (i) mild-to-moderate small lymphocytic infiltration by CD20-CD79a-CD3+CD45RO+CD43+ (CD3 〉 CD45RO) cells, predominantly nodular and/or interstitial (non intrasinusoidal); (ii) pronounced hyperplasia of the erythroid and megakaryocytic series with prominent dyserythropoiesis and dysmegakaryopoiesis, respectively, including abnormal paratrabecular localization, suggestive of myelodysplasia (MDS); and (iii) remarkable shift-to-the-left of the granulocytic series, often with abnormal localization of immature progenitors (ALIP), always with \q2% CD34+ cells. A proportion of cases showed hyperplasia of the granulocytic series. However, a major difference between the two Groups concerned hypoplasia of the granulocytic series, which was noted almost exclusively in group A. We conclude that lymphoma patients treated with Rituximab often develop cytotoxic T cell expansions than can have a variable impact on hematopoiesis, with R-LON perhaps representing the end of a spectrum of T-LGL-mediated autoimmune myelopathy/myelodyplasia. The selective development of R-LON in only a proportion of cases with expanded cytotoxic T cells associated with prominent hypoplasia of the granulocytic series and MDS-like changes of the hematopoietic marrow post Rituximab raises several questions regarding the underlying (genetically determined?) immunopathogenetic mechanisms. Disclosures: No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    URL: Article
    DOI: 10.1182/blood.V118.21.3675.3675
    RVK:
    XA 33000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2011
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