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Agathangelidis A, Ntoufa S, Stamatopoulos K. B cell receptor and antigens in CLL. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 792:1-24. [PMID: 24014290 DOI: 10.1007/978-1-4614-8051-8_1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Nowadays, chronic lymphocytic leukemia (CLL) is considered as a prototypic antigen-driven lymphoma, with antigenic stimuli from the microenvironment promoting tumor outgrowth. Antigen recognition is a function of both the clonotypic B cell receptor immunoglobulin (BcR IG) and various other immune sensors, e.g., the Toll-like receptors. The critical role of BcR IG-mediated signaling in CLL development and evolution is underscored by the following: the disease-biased IG gene repertoire; the subdivision of CLL based on the somatic hypermutation load of the BcR IG into two broad categories with vastly different prognosis and eventual outcome; the existence of subsets of cases with distinct, quasi-identical (stereotyped) BcR IGs; and the clinical efficacy of novel therapeutics inhibiting BcR signaling. Here, we trace the immunogenetic evidence for antigen selection in CLL and also consider the types of implicated antigens as well as the immune signaling pathways relevant for CLL ontogeny and clonal progression.
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2
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Immunoglobulin gene repertoire in chronic lymphocytic leukemia: insight into antigen selection and microenvironmental interactions. Mediterr J Hematol Infect Dis 2012; 4:e2012052. [PMID: 22973496 PMCID: PMC3435129 DOI: 10.4084/mjhid.2012.052] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2012] [Accepted: 07/16/2012] [Indexed: 11/08/2022] Open
Abstract
Immunogenetic analysis of the B cell receptors (BCRs) has been a richly rewarding field for unraveling the pathogenesis of human lymphomas, including CLL. A biased immunoglobulin gene repertoire is seen as evidence for selection of CLL progenitor cells by antigen. Additional corroborative evidence is provided by the differential prognosis of cases with distinct mutational status of the clonotypic BCRs. However, perhaps the strongest immunogenetic evidence for the importance of interactions with microenvironment in driving CLL development and evolution is the existence of subsets of patients with quasi-identical, stereotyped BCRs, collectively accounting for a remarkable one-third of the entire cohort. These observations have been instrumental in shaping the notion that CLL ontogeny is functionally driven and dynamic, rather than a simple stochastic process. From a clinical perspective, ample evidence indicates that immunogenetic information can be used for the biologically and clinically rational categorization of CLL, with important potential implications for basic, translational and clinical research.
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3
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Sozzi E, Amato T, Sahota SS, Nuti S, Raspadori D, Sicuranza A, Cencini E, Tosi P, Lauria F, Forconi F. Lack of allelic exclusion by secondary rearrangements of tumour B-cell receptor light chains in hairy cell leukaemia. Hematol Oncol 2011; 29:31-7. [PMID: 20658474 DOI: 10.1002/hon.952] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Analyses of the tumour immunoglobulin (Ig) gene (IG) heavy (H) and light chains show heterogeneity of mutational status, but reveal common features of ongoing IGH isotype-switching with multiple IGH isotype expression and preference of IG lambda (IGL) light chain with selective use of IGLJ3. Phenotypic and immunogenetic analyses were performed in a series of 105 HCL patients to estimate prevalence of multiple IG light chain expression by the tumour cells. By phenotype, 3/105 HCL (2.9%) expressed double tumour-related Ig kappa (K) and L light chain proteins. By immunogenetic analysis, functional mutated double IGK(I) /IGK(II) , IGK(I) /IGL(I) and IGL(I) /IGL(II) transcripts were cloned and sequenced in 3/71 (4.2%) HCL. These latter three HCL expressed multiple IGH isotypes with mutated IGHVDJ rearrangements at the time of AID transcript expression. Most interestingly, the three cases had reinduced RAG1 transcript. In the double IGL expresser, single-cell analysis documented co-expression of the tumour-related IGLs in 5/6 cells (83%). In the IGK/IGL co-expresser, evidence of surface IgK/IgL isotype proteins confirmed functionality of the tumour-derived transcripts. The evidence of double light chain expression in single HCs and the new observation of RAG re-induction suggest ongoing selective influences on the BCR that may promote or maintain the HCL clone in the periphery.
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Affiliation(s)
- Elisa Sozzi
- Sezione and Unità di Ematologia, Università di Siena & AOUS, Italy
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4
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Abstract
B cell chronic lymphocytic leukaemia (CLL) is the most common adult leukaemia that follows an extremely variable clinical course. Several important prognostic parameters defining pathogenic and clinical subgroups of CLL have been identified and validated recently. The biological significance of immunoglobulin (Ig) heavy chain variable region gene (IgHV) mutational status and associated ZAP-70 over-expression, CD38 and chromosomal aberrations have enabled to identify patients at high risk for early disease progression and inferior survival. Moreover, studies of the B cell antigen receptor (BCR) structure and receptor signalling have been most helpful in revealing some new aspects of the biology of this disease. In particular, the analysis of IG genes has revealed that the expressed IgHV/IgKV/IgLV gene repertoires of CLL cells differ from those of normal B cells. A further unique feature of the CLL IG repertoire is the existence of subsets of cases with "stereotyped" BCRs. Accumulating molecular and phenotypic data support the notion that CLL development and evolution is not a simple scholastic event and strongly indicates a role for antigen in driving the cell of origin for at least some subsets of CLL cases.
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5
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Chiotoglou I, Smilevska T, Samara M, Likousi S, Belessi C, Athanasiadou I, Stavroyianni N, Samara S, Laoutaris N, Vamvakopoulos N, Anagnostopoulos A, Fassas A, Stamatopoulos K, Kollia P. Predominantly post-transcriptional regulation of activation molecules in chronic lymphocytic leukemia: the case of transferrin receptors. Blood Cells Mol Dis 2008; 41:203-9. [PMID: 18621559 DOI: 10.1016/j.bcmd.2008.05.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 05/05/2008] [Accepted: 05/05/2008] [Indexed: 11/28/2022]
Abstract
Transcriptional and post-transcriptional control mechanisms have a differential impact on cellular physiology depending on activation status. Several lines of evidence suggest that chronic lymphocytic leukemia (CLL) malignant B cells resemble antigen-experienced and activated B cells. In the present study, we investigated the expression of transferrin receptor 1 (TfR1, CD71), one of the "classical" markers up-regulated upon B-cell activation, and TfR2, a novel receptor for transferrin, in peripheral blood CD19+ B cells from ten healthy individuals and 76 patients with CLL so as to gain insight into potential disease-related differences in underlying regulatory mechanisms. Marked differences in the production and expression of these receptors were detected in malignant but not in normal B cells. Specifically, TfR1 mRNA and protein levels were significantly higher in comparison to TfR2, both in normal and malignant B cells. Furthermore, discrepancies between TfR mRNA and protein expression were observed in CLL; in contrast, mRNA and protein expression levels were generally concordant in normal B cells. Exposure to actinomycin D decreased TfR1 and TfR2 mRNA levels in normal CD19+ B cells but had no effect on CLL malignant cells. The protein synthesis inhibitor cycloheximide had opposing effects in normal vs. CLL malignant B cells: thus, TfR1 and TfR2 mRNA levels were increased in normal B cells, whereas they were unaffected or even suppressed in CLL malignant B cells. These results allude to differential regulation of TfR1 and TfR2 expression in normal B cells vs. CLL. In normal B cells, transcriptional mechanisms exert a critical control over TfR1 and TfR2 expression, whereas in CLL post-transcriptional mechanisms seem to play a complementary and perhaps more important role. This type of control appears to be especially suited for modulation of genes implicated in proliferation of activated cells, like CLL malignant B cells.
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Affiliation(s)
- Ioanna Chiotoglou
- Laboratory of Cytogenetics and Molecular Genetics, School of Medicine, University of Thessaly, 41222 Larissa, Greece
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6
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Martín-Jiménez P, García-Sanz R, González D, Balanzategui A, Pérez JJ, Caballero MD, Sarasquete ME, Galende J, Orfao A, López-Berges MC, San Miguel JF, González M. Molecular Characterization of Complete and Incomplete Immunoglobulin Heavy Chain Gene Rearrangements in Hairy Cell Leukemia. ACTA ACUST UNITED AC 2007; 7:573-9. [DOI: 10.3816/clm.2007.n.043] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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7
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Lee CEH, Jackson KJL, Sewell WA, Collins AM. Use of IGHJ and IGHD gene mutations in analysis of immunoglobulin sequences for the prognosis of chronic lymphocytic leukemia. Leuk Res 2006; 31:1247-52. [PMID: 17169423 DOI: 10.1016/j.leukres.2006.10.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 09/21/2006] [Accepted: 10/19/2006] [Indexed: 11/28/2022]
Abstract
The level of somatic point mutation in immunoglobulin genes is an important prognostic indicator for patients with chronic lymphocytic leukemia (CLL). Mutation analysis presently focuses solely upon the heavy chain IGHV gene, however mutation is a stochastic process that also targets IGHD and IGHJ genes. Here, we evaluate the completeness and reliability of the reported IGHJ gene repertoire, and demonstrate the likely consequences of the inclusion of IGHD and IGHJ mutations in CLL analysis, using a dataset of 607 sequences. Inclusion of these mutations would lead to the re-classification of many sequences, which should significantly improve the prognostic value of mutation analysis.
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Affiliation(s)
- Cindy E H Lee
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, Sydney, NSW 2052, Australia
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8
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Fecteau JF, Côté G, Néron S. A new memory CD27-IgG+ B cell population in peripheral blood expressing VH genes with low frequency of somatic mutation. THE JOURNAL OF IMMUNOLOGY 2006; 177:3728-36. [PMID: 16951333 DOI: 10.4049/jimmunol.177.6.3728] [Citation(s) in RCA: 223] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In humans, up to 40% of peripheral B cells express CD27 and have hypermutated variable regions in their Ig genes. The CD27+ B cells are considered to be derived from germinal center following specific antigenic stimulation. Actually, somatic hypermutation in Ig genes and CD27 expression are hallmarks of memory B cells. However, the blood IgM+ IgD+ CD27+ B cells were recently associated to splenic marginal zone B cells and proposed to be a subset distinct from germinal center-derived memory B cells showing premutated Igs. The results presented herein further weaken this bona fide association because B cells expressing surface IgG, but not CD27, were found in human blood. Representing 1-4% of all peripheral B cells and approximately 25% of the IgG+ blood B cells, this population expressed mutated IgG genes showing antigenic selection characteristics but with lower mutation frequencies than that of CD27+ IgG+ B cells. However, their morphology and phenotype were similar to that of CD27+ IgG+ cells. Interestingly, the proportion of IgG2 over IgG3 transcripts was opposite in CD27- IgG+ and CD27+ IgG+ cells, suggesting distinct functions or origins. Overall, these findings extend the memory B cell reservoir beyond the CD27+ compartment and could provide further insights into B cell disorders of unknown etiology.
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Affiliation(s)
- Jessie F Fecteau
- Héma-Québec, Recherche et Développement, Sainte-Foy, Quebec, Canada
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9
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Stamatopoulos K, Belessi C, Moreno C, Boudjograh M, Guida G, Smilevska T, Belhoul L, Stella S, Stavroyianni N, Crespo M, Hadzidimitriou A, Sutton L, Bosch F, Laoutaris N, Anagnostopoulos A, Montserrat E, Fassas A, Dighiero G, Caligaris-Cappio F, Merle-Béral H, Ghia P, Davi F. Over 20% of patients with chronic lymphocytic leukemia carry stereotyped receptors: Pathogenetic implications and clinical correlations. Blood 2006; 109:259-70. [PMID: 16985177 DOI: 10.1182/blood-2006-03-012948] [Citation(s) in RCA: 382] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The chronic lymphocytic leukemia (CLL) immunoglobulin repertoire is biased and characterized by the existence of subsets of cases with closely homologous ("stereotyped") complementarity-determining region 3 (CDR3) sequences. In the present series, 201 (21.9%) of 916 patients with CLL expressed IGHV genes that belonged to 1 of 48 different subsets of sequences with stereotyped heavy chain (H) CDR3. Twenty-six subsets comprised 3 or more sequences and were considered "confirmed." The remaining subsets comprised pairs of sequences and were considered "potential"; public database CLL sequences were found to be members of 9 of 22 "potential" subsets, thereby allowing us to consider them also "confirmed." The chance of belonging to a subset exceeded 35% for unmutated or selected IGHV genes (eg, IGHV1-69/3-21/4-39). Comparison to non-CLL public database sequences showed that HCDR3 restriction is "CLL-related." CLL cases with selected stereotyped immunoglobulins (IGs) were also found to share unique biologic and clinical features. In particular, cases expressing stereotyped IGHV4-39/IGKV1-39-1D-39 and IGHV4-34/IGKV2-30 were always IgG-switched. In addition, IGHV4-34/IGKV2-30 patients were younger and followed a strikingly indolent disease, contrasting other patients (eg, those expressing IGHV3-21/IGLV3-21) who experienced an aggressive disease, regardless of IGHV mutations. These findings suggest that a particular antigen-binding site can be critical in determining the clinical features and outcome for at least some CLL patients.
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MESH Headings
- ADP-ribosyl Cyclase 1/analysis
- Amino Acid Sequence
- B-Lymphocyte Subsets/immunology
- B-Lymphocyte Subsets/pathology
- Base Sequence
- Cohort Studies
- Epitopes
- Follow-Up Studies
- France
- Gene Frequency
- Gene Rearrangement, B-Lymphocyte, Heavy Chain
- Genes, Immunoglobulin
- Greece
- Humans
- Immunoglobulin Class Switching
- Immunoglobulin Heavy Chains/genetics
- Immunoglobulin Switch Region
- Immunoglobulin Variable Region/genetics
- Italy
- Leukemia, Lymphocytic, Chronic, B-Cell/etiology
- Leukemia, Lymphocytic, Chronic, B-Cell/immunology
- Molecular Sequence Data
- Polymerase Chain Reaction
- Rheumatoid Factor/immunology
- Sequence Homology
- Somatic Hypermutation, Immunoglobulin
- Spain
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Affiliation(s)
- Kostas Stamatopoulos
- Hematology Department and HCT Unit, G. Papanicolaou Hospital, Thessaloniki, Greece
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10
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Belessi CJ, Davi FB, Stamatopoulos KE, Degano M, Andreou TM, Moreno C, Merle-Béral H, Crespo M, Laoutaris NP, Montserrat E, Caligaris-Cappio F, Anagnostopoulos AZ, Ghia P. IGHV gene insertions and deletions in chronic lymphocytic leukemia: "CLL-biased" deletions in a subset of cases with stereotyped receptors. Eur J Immunol 2006; 36:1963-74. [PMID: 16783849 DOI: 10.1002/eji.200535751] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Nucleotide insertions/duplications or deletions in immunoglobulin heavy chain genes have been found in 24/760 patients (3.15%) with chronic lymphocytic leukemia (CLL). In 21/24 cases, the inserted/duplicated or lost nucleotides occurred in multiples of 3; therefore, the original reading frame was maintained and a potentially intact receptor was coded. The pattern and location of insertions/duplications or deletions in CLL and their restriction to mutated IGHV rearranged genes strongly suggests that they resulted from somatic hypermutation. Their incidence in CLL is consistent with previous reports in normal, auto-reactive and neoplastic human B cells, thus seemingly indicating that these modifications generally arise without any particular disease-specific associations. A striking exception to this rule was identified in CLL IGHV3-21-expressing cases: one amino acid was deleted from the CDR2 region in 16/63 (25.4%) mutated CLL IGHV3-21 sequences (including public database-derived IGHV3-21 CLL cases + the present series) vs. only 2/257 (0.78%) public database-derived mutated non-CLL IGHV3-21 sequences; 15/16 CLL IGHV3-21 sequences carrying this deletion belonged to a subset with unique, shared HCDR3 and light chain CDR3 motifs. This finding further supports the idea of selective antigenic pressures playing a pathogenetic role in some CLL cases.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Complementarity Determining Regions/genetics
- Gene Deletion
- Gene Rearrangement, B-Lymphocyte, Heavy Chain
- Humans
- Immunoglobulin Heavy Chains/genetics
- Immunoglobulin Variable Region/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/immunology
- Molecular Sequence Data
- Mutagenesis, Insertional
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, T-Cell/genetics
- Somatic Hypermutation, Immunoglobulin
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11
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Abstract
Hairy-cell leukaemia (HCL) has long been recognized as distinct from other chronic B-cell malignancies, but several questions remain unanswered. What is the HCL cell of origin? Why does HCL lack the hallmarks of most mature B-cell tumours (for example, chromosomal translocations and consistent lymph node involvement) and show unique features like 'hairy' morphology and bone-marrow fibrosis? Gene-expression profiling and other studies have recently provided new insights into HCL biology and have the potential to affect clinical practice.
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Affiliation(s)
- Enrico Tiacci
- Institute of Haematology, University of Perugia, Italy.
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12
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Stamatopoulos K, Belessi C, Papadaki T, Kalagiakou E, Stavroyianni N, Douka V, Afendaki S, Saloum R, Parasi A, Anagnostou D, Laoutaris N, Fassas A, Anagnostopoulos A. Immunoglobulin heavy- and light-chain repertoire in splenic marginal zone lymphoma. Mol Med 2006; 10:89-95. [PMID: 15706403 PMCID: PMC1431370 DOI: 10.2119/2005-00001.stamatopoulos] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Accepted: 01/17/2005] [Indexed: 11/06/2022] Open
Abstract
The considerable heterogeneity in morphology, immunophenotype, genotype, and clinical behavior of splenic marginal zone lymphoma (SMZL) hinders firm conclusions on the origin and differentiation stage of the neoplastic cells. Immunoglobulin (IG) gene usage and somatic mutation patterns were studied in a series of 43 SMZL cases. Clonal IGHV-D-J rearrangements were amplified in 42/43 cases (4 cases carried double rearrangements). Among IGHV-D-J rearrangements, IGHV3 and IGHV4 subgroup genes were used with the highest frequency. Nineteen IGHV genes were unmutated (> 98% homology to the closest germline IGHV gene), whereas 27/46 were mutated. Clonal IGKV-J and IGLV-J gene rearrangements were amplified in 36/43 cases, including 31 IGKV-J (8/31 in lambda light-chain expressing cases) and 12 IGLV-J rearrangements; 9/31 IGKV and 6/12 IGLV sequences were mutated. IGKV-J and IGLV-J rearrangements used 14 IGKV and 9 IGLV different germline genes. Significant evidence for positive selection by classical T-dependent antigen was found in only 5/27 IGHV and 6/15 IGKV+IGLV mutated genes. These results provide evidence for the diverse B-cell subpopulations residing in the SMZ, which could represent physiologic equivalents of distinct SMZL subtypes. Furthermore, they indicate that in SMZL, as in other B cell malignancies, a complementarity imprint of antigen selection might be witnessed either by IGHV, IGKV, or IGLV rearranged sequences.
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13
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Lane BS, Mensah AA, Lin K, Pettitt AR, Sherrington PD. Analysis of VH gene sequences using two web-based immunogenetics resources gives different results, but the affinity maturation status of chronic lymphocytic leukaemia clones as assessed from either of the resulting data sets has no prognostic significance. Leukemia 2005; 19:741-9. [PMID: 15772699 DOI: 10.1038/sj.leu.2403720] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Some cellular and molecular features of chronic lymphocytic leukaemia (CLL) cells that are associated with prognosis may reflect the context within which their progenitors encountered antigen. It follows that the nature of antigen drive in CLL could influence the clinical course and we were prompted to assess the impact, if any, of affinity maturation (an antigen-driven process) on prognosis. Statistical models for assessing affinity maturation status are typically applied to V(H) gene sequence data analysed using a web-based resource like IMGT or VBASE. Since these resources differ with respect to some key relevant features, we evaluated a cohort of CLL cases by applying statistical models to V(H) data derived from both IMGT and VBASE. Important differences between the resulting data sets became apparent. These resulted from database variance and because IMGT and VBASE define complementarity-determining and framework regions (CDRs, FRs) in different ways. Thus, the numbers of mutations identified and their distribution between CDRs/FRs varied between the data sets for the majority of clones. Consequently, two different but overlapping sets of cases with evidence of affinity maturation were defined. Notwithstanding their differences, no significant associations of affinity maturation status with CD38 expression, p53 functional status or survival were identifiable in either data set.
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MESH Headings
- ADP-ribosyl Cyclase/genetics
- ADP-ribosyl Cyclase 1
- Aged
- Antigens, CD/genetics
- Clone Cells
- Computational Biology
- DNA Mutational Analysis/methods
- Databases, Genetic
- Female
- Humans
- Immunogenetics/statistics & numerical data
- Immunoglobulin Fragments/genetics
- Immunoglobulin Heavy Chains/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/mortality
- Male
- Membrane Glycoproteins
- Mutation
- Prognosis
- Reproducibility of Results
- Survival Analysis
- Tumor Suppressor Protein p53/physiology
- User-Computer Interface
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Affiliation(s)
- B S Lane
- Department of Haematology, Royal Liverpool University Hospital, Liverpool, UK
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14
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Thorsélius M, Walsh SH, Thunberg U, Hagberg H, Sundström C, Rosenquist R. Heterogeneous somatic hypermutation status confounds the cell of origin in hairy cell leukemia. Leuk Res 2005; 29:153-8. [PMID: 15607363 DOI: 10.1016/j.leukres.2004.05.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Accepted: 05/19/2004] [Indexed: 10/26/2022]
Abstract
Hairy cell leukemia (HCL) is thought to arise from a post-germinal center (GC) B-cell, however the exact normal counterpart remains unclear. We performed VH gene analysis of 32 HCL cases, revealing somatically mutated VH genes (<98% homology) in 27 cases and unmutated VH genes in five cases, four of which displayed germline VH genes. Intraclonal heterogeneity was evident in the majority of eight mutated HCLs investigated, although at a lower level compared to GC-derived lymphomas. A novel finding of preferential VH3-30 gene usage was detected (19% of HCLs). Our data confounds the postulated post-GC origin in HCL considering (1) the finding of unmutated HCLs, generally correlating with a pre-GC origin, and (2) the presence of intraclonal variation in mutated HCLs. The latter suggests that the transformed B-cell was frozen when it still had an active mutation process, implying a closer relation to the GC than previously assumed. Furthermore, restricted VH3-30 usage indicates that antigen selection could be a promoting factor in HCL development.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Base Sequence
- Female
- Gene Rearrangement, B-Lymphocyte, Heavy Chain
- Humans
- Immunoglobulin Heavy Chains/analysis
- Immunoglobulin Heavy Chains/genetics
- Leukemia, B-Cell/genetics
- Leukemia, B-Cell/immunology
- Leukemia, B-Cell/pathology
- Leukemia, Hairy Cell/genetics
- Leukemia, Hairy Cell/immunology
- Leukemia, Hairy Cell/pathology
- Male
- Middle Aged
- Molecular Sequence Data
- Somatic Hypermutation, Immunoglobulin/genetics
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Affiliation(s)
- Mia Thorsélius
- Department of Genetics and Pathology, Rudbeck Laboratary, Uppsala University, SE-751 85 Uppsala, Sweden
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15
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Forconi F, Sahota SS, Raspadori D, Ippoliti M, Babbage G, Lauria F, Stevenson FK. Hairy cell leukemia: at the crossroad of somatic mutation and isotype switch. Blood 2004; 104:3312-7. [PMID: 15284115 DOI: 10.1182/blood-2004-03-0950] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hairy cell leukemia (HCL) commonly expresses multiple immunoglobulin isotypes, a feature rare in other B-cell malignancies or in normal B cells. In HCL, there is no phenotypic evidence for subpopulations, and single cells from one previous case contained transcripts for several isotypes. This raises the questions of the differentiation status of the cell of origin and of posttransformation events. We have investigated 9 cases, all expressing multiple immunoglobulin isotypes. Multiple tumor-derived variable-(diversity)-joining-constant mu delta, gamma, alpha (V(D)J-Cmu, delta, gamma, alpha) transcripts were confirmed in single cells of a further case. All cases were negative for germinal center (GC)-associated markers CD27 and CD38. Seven of 9 cases had mutated V(H) genes, with low levels of intraclonal heterogeneity, but 2 of 9 were unmutated, indicative of pre-GC origin. Eight of 9 cases expressed activation-induced cytidine deaminase (AID), a molecule essential for somatic mutation and isotype switch. All cases expressed germ line heavy-chain I exon (I(H))-C(H) transcripts which paralleled surface immunoglobulin (sIg) isotype. Significantly, no circle transcripts indicative of deletional recombination of switched isotypes were detectable in 9 of 9 cases. These data indicate heterogeneity in the cell of origin in terms of mutational status, but reveal common features of AID expression and isotype-switching events occurring prior to deletional recombination. Both mutational and switching events may be influenced by environmental factors at extrafollicular sites.
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Affiliation(s)
- Francesco Forconi
- Unità Operativa Complessa Ematologia e Trapianti, Dipartimento di Medicina Clinica e Scienze Immunologiche, Università di Siena, Italy.
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