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  • 1
    In: Blood, American Society of Hematology, Vol. 137, No. 10 ( 2021-03-11), p. 1365-1376
    Abstract: Chronic lymphocytic leukemia (CLL) is characterized by the existence of subsets of patients with (quasi)identical, stereotyped B-cell receptor (BcR) immunoglobulins. Patients in certain major stereotyped subsets often display remarkably consistent clinicobiological profiles, suggesting that the study of BcR immunoglobulin stereotypy in CLL has important implications for understanding disease pathophysiology and refining clinical decision-making. Nevertheless, several issues remain open, especially pertaining to the actual frequency of BcR immunoglobulin stereotypy and major subsets, as well as the existence of higher-order connections between individual subsets. To address these issues, we investigated clonotypic IGHV-IGHD-IGHJ gene rearrangements in a series of 29 856 patients with CLL, by far the largest series worldwide. We report that the stereotyped fraction of CLL peaks at 41% of the entire cohort and that all 19 previously identified major subsets retained their relative size and ranking, while 10 new ones emerged; overall, major stereotyped subsets had a cumulative frequency of 13.5%. Higher-level relationships were evident between subsets, particularly for major stereotyped subsets with unmutated IGHV genes (U-CLL), for which close relations with other subsets, termed “satellites,” were identified. Satellite subsets accounted for 3% of the entire cohort. These results confirm our previous notion that major subsets can be robustly identified and are consistent in relative size, hence representing distinct disease variants amenable to compartmentalized research with the potential of overcoming the pronounced heterogeneity of CLL. Furthermore, the existence of satellite subsets reveals a novel aspect of repertoire restriction with implications for refined molecular classification of CLL.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2021
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  • 2
    In: Frontiers in Oncology, Frontiers Media SA, Vol. 12 ( 2023-1-16)
    Abstract: Detection of patient- and tumor-specific clonally rearranged immune receptor genes using real-time quantitative (RQ)-PCR is an accepted method in the field of precision medicine for hematologic malignancies. As individual primers are needed for each patient and leukemic clone, establishing performance specifications for the method faces unique challenges. Results for series of diagnostic assays for CLL and ALL patients demonstrate that the analytic performance of the method is not dependent on patients’ disease characteristics. The calibration range is linear between 10 -1 and 10 -5 for 90% of all assays. The detection limit of the current standardized approach is between 1.8 and 4.8 cells among 100,000 leukocytes. RQ-PCR has about 90% overall agreement to flow cytometry and next generation sequencing as orthogonal methods. Accuracy and precision across different labs, and above and below the clinically applied cutoffs for minimal/measurable residual disease (MRD) demonstrate the robustness of the technique. The here reported comprehensive, IVD-guided analytical validation provides evidence that the personalized diagnostic methodology generates robust, reproducible and specific MRD data when standardized protocols for data generation and evaluation are used. Our approach may also serve as a guiding example of how to accomplish analytical validation of personalized in-house diagnostics under the European IVD Regulation.
    Type of Medium: Online Resource
    ISSN: 2234-943X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
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  • 3
    Online Resource
    Online Resource
    The American Association of Immunologists ; 2002
    In:  The Journal of Immunology Vol. 169, No. 1 ( 2002-07-01), p. 271-276
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 169, No. 1 ( 2002-07-01), p. 271-276
    Abstract: Two polymorphisms of the human Igλ (IGL) locus have been described. The first polymorphism concerns a single, 2- or 3-fold amplification of 5.4 kb of DNA in the Cλ2-Cλ3 region. The second polymorphism is the Mcg−Ke+Oz− isotype, which has only been defined via serological analyses in Bence-Jones proteins of multiple myeloma patients and was assumed to be encoded by a polymorphic Cλ2 segment because of its high homology with the Mcg−Ke−Oz− Cλ2 isotype. It has been speculated that the Mcg−Ke+Oz− isotype might be encoded by a Cλ gene segment of the amplified Cλ2-Cλ3 region. We now unraveled both IGL gene polymorphisms. The amplification polymorphism appeared to result from a duplication, triplication, or quadruplication of a functional J-Cλ2 region and is likely to have originated from unequal crossing over of the J-Cλ2 and J-Cλ3 region via a 2.2-kb homologous repeat. The amplification polymorphism was found to result in the presence of one to five extra functional J-Cλ2 per genome regions, leading to decreased Igκ:Igλ ratios on normal peripheral blood B cells. Via sequence analysis, we demonstrated that the Mcg−Ke+Oz− isotype is encoded by a polymorphic Cλ2 segment that differs from the normal Cλ2 gene segment at a single nucleotide position. This polymorphism was identified in only 1.5% (2 of 134) of individuals without J-Cλ2 amplification polymorphism and was not found in the J-Cλ2 amplification polymorphism of 44 individuals, indicating that the two IGL gene polymorphisms are not linked.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2002
    detail.hit.zdb_id: 1475085-5
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  • 4
    In: Blood, American Society of Hematology, Vol. 98, No. 8 ( 2001-10-15), p. 2456-2465
    Abstract: T-cell receptor (TCR) gene rearrangements are mediated via V(D)J recombination, which is strictly regulated during lymphoid differentiation, most probably through the action of specific transcription factors. Investigated was whether cotransfection ofRAG1 and RAG2 genes in combination with lymphoid transcription factors can induce TCR gene rearrangements in nonlymphoid human cells. Transfection experiments showed that basic helix-loop-helix transcription factors E2A and HEB induce rearrangements in the TCRD locus (Dδ2-Dδ3 and Vδ2-Dδ3) and TCRG locus (ψ Vγ7-Jγ2.3 and Vγ8-Jγ2.3). Analysis of these rearrangements and their circular excision products revealed some peculiar characteristics. The Vδ2-Dδ3 rearrangements were formed by direct coupling without intermediate Dδ2 gene segment usage, and most Dδ2-Dδ3 recombinations occurred via direct coupling of the respective upstream and downstream recombination signal sequences (RSSs) with deletion of the Dδ2 and Dδ3 coding sequences. Subsequently, the E2A/HEB–induced TCR gene recombination patterns were compared with those in early thymocytes and acute lymphoblastic leukemias of T- and B-lineage origin, and it was found that the TCR rearrangements in the transfectants were early (immature) and not necessarily T-lineage specific. Apparently, some parts of theTCRD (Vδ2-Dδ region) and TCRG genes are accessible for recombination not only in T cells, but also in early B-cells and even in nonlymphoid cells if the appropriate transcription factors are present. The transfection system described here appeared to be useful for studying the accessibility of immunoglobulin and TCR genes for V(D)J recombination, but might also be applied to study the induction of RSS-mediated chromosome aberrations.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2001
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  • 5
    Online Resource
    Online Resource
    The American Association of Immunologists ; 2004
    In:  The Journal of Immunology Vol. 173, No. 6 ( 2004-09-15), p. 3878-3888
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 173, No. 6 ( 2004-09-15), p. 3878-3888
    Abstract: In addition to the classical Vκ-Jκ, Vκ-κ deleting element (Kde), and intron-Kde gene rearrangements, atypical recombinations involving Jκ recombination signal sequence (RSS) or intronRSS elements can occur in the Igκ (IGK) locus, as observed in human B cell malignancies. In-depth analysis revealed that atypical JκRSS-intronRSS, Vκ-intronRSS, and JκRSS-Kde recombinations not only occur in B cell malignancies, but rather reflect physiological gene rearrangements present in normal human B cells as well. Excision circle analysis and recombination substrate assays can discriminate between single-step vs multistep rearrangements. Using this combined approach, we unraveled that the atypical Vκ-intronRSS and JκRSS-Kde pseudohybrid joints most probably result from ongoing recombination following an initial aberrant JκRSS-intronRSS signal joint formation. Based on our observations in normal and malignant human B cells, a model is presented to describe the sequential (classical and atypical) recombination events in the human IGK locus and their estimated relative frequencies (0.2–1.0 vs & lt;0.03). The initial JκRSS-intronRSS signal joint formation (except for Jκ1RSS-intronRSS) might be a side event of an active V(D)J recombination mechanism, but the subsequent formation of Vκ-intronRSS and JκRSS-Kde pseudohybrid joints can represent an alternative pathway for IGK allele inactivation and allelic exclusion, in addition to classical Cκ deletions. Although usage of this alternative pathway is limited, it seems essential for inactivation of those IGK alleles that have undergone initial aberrant recombinations, which might otherwise hamper selection of functional Ig L chain proteins.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2004
    detail.hit.zdb_id: 1475085-5
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  • 6
    In: Blood, American Society of Hematology, Vol. 93, No. 9 ( 1999-05-01), p. 3033-3043
    Abstract: Recent studies have identified several populations of progenitor cells in the human thymus. The hematopoietic precursor activity of these populations has been determined. The most primitive human thymocytes express high levels of CD34 and lack CD1a. These cells acquire CD1a and differentiate into CD4+CD8+ through CD3−CD4+CD8− and CD3−CD4+CD8+β− intermediate populations. The status of gene rearrangements in the various TCR loci, in particular of TCRδ and TCRγ, has not been analyzed in detail. In the present study we have determined the status of TCR gene rearrangements of early human postnatal thymocyte subpopulations by Southern blot analysis. Our results indicate that TCRδ rearrangements initiate in CD34+CD1a− cells preceding those in the TCRγ and TCRβ loci that commence in CD34+CD1a+ cells. Furthermore, we have examined at which cellular stage TCRβ selection occurs in humans. We analyzed expression of cytoplasmic TCRβ and cell-surface CD3 on thymocytes that lack a mature TCRβ. In addition, we overexpressed a constitutive-active mutant of p56lckF505 by retrovirus-mediated gene transfer in sequential stages of T-cell development and analyzed the effect in a fetal thymic organ culture system. Evidence is presented that TCRβ selection in humans is initiated at the transition of the CD3−CD4+CD8− into the CD4+CD8+β− stage.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1999
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 7
    In: The Journal of Molecular Diagnostics, Elsevier BV, Vol. 7, No. 4 ( 2005-10), p. 495-503
    Type of Medium: Online Resource
    ISSN: 1525-1578
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    Language: English
    Publisher: Elsevier BV
    Publication Date: 2005
    detail.hit.zdb_id: 2032654-3
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  • 8
    In: Blood, American Society of Hematology, Vol. 93, No. 9 ( 1999-05-01), p. 3033-3043
    Abstract: Recent studies have identified several populations of progenitor cells in the human thymus. The hematopoietic precursor activity of these populations has been determined. The most primitive human thymocytes express high levels of CD34 and lack CD1a. These cells acquire CD1a and differentiate into CD4+CD8+ through CD3−CD4+CD8− and CD3−CD4+CD8+β− intermediate populations. The status of gene rearrangements in the various TCR loci, in particular of TCRδ and TCRγ, has not been analyzed in detail. In the present study we have determined the status of TCR gene rearrangements of early human postnatal thymocyte subpopulations by Southern blot analysis. Our results indicate that TCRδ rearrangements initiate in CD34+CD1a− cells preceding those in the TCRγ and TCRβ loci that commence in CD34+CD1a+ cells. Furthermore, we have examined at which cellular stage TCRβ selection occurs in humans. We analyzed expression of cytoplasmic TCRβ and cell-surface CD3 on thymocytes that lack a mature TCRβ. In addition, we overexpressed a constitutive-active mutant of p56lckF505 by retrovirus-mediated gene transfer in sequential stages of T-cell development and analyzed the effect in a fetal thymic organ culture system. Evidence is presented that TCRβ selection in humans is initiated at the transition of the CD3−CD4+CD8− into the CD4+CD8+β− stage.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1999
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 9
    In: Blood, American Society of Hematology, Vol. 119, No. 19 ( 2012-05-10), p. 4467-4475
    Abstract: Mounting evidence indicates that grouping of chronic lymphocytic leukemia (CLL) into distinct subsets with stereotyped BCRs is functionally and prognostically relevant. However, several issues need revisiting, including the criteria for identification of BCR stereotypy and its actual frequency as well as the identification of “CLL-biased” features in BCR Ig stereotypes. To this end, we examined 7596 Ig VH (IGHV-IGHD-IGHJ) sequences from 7424 CLL patients, 3 times the size of the largest published series, with an updated version of our purpose-built clustering algorithm. We document that CLL may be subdivided into 2 distinct categories: one with stereotyped and the other with nonstereotyped BCRs, at an approximate ratio of 1:2, and provide evidence suggesting a different ontogeny for these 2 categories. We also show that subset-defining sequence patterns in CLL differ from those underlying BCR stereotypy in other B-cell malignancies. Notably, 19 major subsets contained from 20 to 213 sequences each, collectively accounting for 943 sequences or one-eighth of the cohort. Hence, this compartmentalized examination of VH sequences may pave the way toward a molecular classification of CLL with implications for targeted therapeutic interventions, applicable to a significant number of patients assigned to the same subset.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2012
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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