| 1. |
- Grimsholm, O., et al.
(author)
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The Interplay between CD27(dull) and CD27(brig)(ht) B Cells Ensures the Flexibility, Stability, and Resilience of Human B Cell Memory
- 2020
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In: Cell Reports. - : Elsevier BV. - 2211-1247. ; 30:9
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Journal article (peer-reviewed)abstract
- Memory B cells (MBCs) epitomize the adaptation of the immune system to the environment. We identify two MBC subsets in peripheral blood, CD27(dull) and CD27(bright) MBCs, whose frequency changes with age. Heavy chain variable region (VH) usage, somatic mutation frequency replacement-to-silent ratio, and CDR3 property changes, reflecting consecutive selection of highly antigen-specific, low cross-reactive antibody variants, all demonstrate that CD27(du)(ll) and CD27(bright) MBCs represent sequential MBC developmental stages, and stringent antigen-driven pressure selects CD27(du)(ll) into the CD27(bright) MBC pool. Dynamics of human MBCs are exploited in pregnancy, when 50% of maternal MBCs are lost and CD27(du)(ll) MBCs transit to the more differentiated CD27 bright stage. In the postpartum period, the maternal MBC pool is replenished by the expansion of persistent CD27(du)(ll) clones. Thus, the stability and flexibility of human B cell memory is ensured by CD27(du)(ll) MBCs that expand and differentiate in response to change.
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| 2. |
- Minafo, Y. A., et al.
(author)
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A stereotyped light chain may shape virus-specific B-cell receptors in HCV-dependent lymphoproliferative disorders
- 2020
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In: Genes and Immunity. - : Springer Science and Business Media LLC. - 1466-4879 .- 1476-5470. ; 21:131-135
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Journal article (peer-reviewed)abstract
- Hepatitis C virus (HCV) causes B-cell lymphoproliferative disorders (LPDs) expressing stereotyped B-cell receptors (BCRs) endowed with rheumatoid factor (RF) activity and putatively recognizing the HCV E2 protein. To further untangle the shaping and function of these BCRs, we analyzed immunoglobulin gene rearrangements of monoclonal B cells from 13 patients with HCV-associated LPDs and correlated their features with the clinical outcomes of antiviral therapy. While only two patients shared a stereotyped heavy-chain complementarity determining region 3 (CDR3) sequence, two kappa chain CDR3 stereotyped sequences accounted for 77% of BCRs. Light chains were enriched in sequences homologous to anti-HCV E2 antibodies compared with heavy chains (7/13 vs. 0/13; p = 0.005). Anti-HCV E2 homology was uniquely associated (7/7 vs. 0/6; p = 0.0006) with a stereotyped CDR3 sequence encoded by IGKV3-20/3D-20 gene(s) accounting for 54% of BCRs. An IGKV3-15/IGKJ1-encoded stereotyped sequence homologous to WA RF accounted for 23% of BCRs. LPDs expressing KCDR3s homologous to anti-HCV E2 antibodies responded more frequently to the eradication of HCV by antiviral therapy (6/6 vs. 1/6; p = 0.015). These findings, although limited by the small sample size, suggest that a stereotyped KCDR3 may predominantly shape anti-HCV specificity of BCRs, possibly providing a signature that may help identifying bona fide HCV-dependent LPDs.
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| 3. |
- Wennerås, Christine, 1963, et al.
(author)
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Infection with Neoehrlichia mikurensis promotes the development of malignant B- cell lymphomas
- 2023
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In: British Journal of Haematology. - : Wiley. - 0007-1048 .- 1365-2141. ; 201:3, s. 480-488
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Journal article (peer-reviewed)abstract
- The tick-borne pathogen Neoehrlichia (N.) mikurensis is implicated in persistent infection of the vascular endothelium. B cells are crucial for the host defence to this infection. Chronic stimulation of B cells may result in B-cell transformation and lymphoma. Five patients with malignant B-cell lymphoma and concomitant N. mikurensis infection were investigated regarding clinical picture, lymphoma subtype, B-cell lymphoma immunophenotype and IGHV (variable region of the immunoglobulin heavy) gene repertoire. Three of the five patients improved markedly and ceased lymphoma treatment after doxycycline treatment to eliminate N. mikurensis. Sequencing the B-cell lymphoma IGHV genes revealed preferred usage of the IGHV1 (IGHV1-2, and -69) and IGHV3 (IGHV3-15, -21, -23) families. In conclusion, N. mikurensis infection may drive the development of malignant B-cell lymphomas. Eradication of the pathogen appears to induce remission with apparent curing of the lymphoma in some cases.
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| 4. |
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| 5. |
- Aranburu, A., et al.
(author)
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Transcription factor AP-4 is a ligand for immunoglobulin-κ promoter E-box elements
- 2001
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In: Biochemical Journal. - 0264-6021. ; 354:2, s. 431-438
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Journal article (peer-reviewed)abstract
- Immunoglobulin (Ig)-κ promoters from humans and mice share conserved sequences. The octamer element is common to all Ig promoters and pivotal for their function. However, other conserved sequence motifs, that differ between lg variable gene families, are required for normal promoter function. These conserved motifs do not stimulate transcription in the absence of an octamer. One example is an E-box of the E47/E12 type (5′-CAGCTG-3′), which is found in all promoters of the human and murine Ig-κ gene subgroups/families, with the exception of subgroups II and VI and their related murine families. In the present study we show that the ubiquitously expressed transcription factor AP-4, and not E47, interacts specifically with the κ promoter E-boxes when tested in electrophoretic mobility-shift assays using nuclear extracts derived from human and murine B-cell lines. Furthermore, AP-4, unlike E47, did not act as a transactivator, which is in agreement with previous studies on intact κ promoters, showing that transcription is absent when the octamer element has been mutated. Based on these data, and the conservation of the 5′-CAGCTG-3′ motif among human and murine κ promoters, we propose that AP-4 is the major ligand for Ig-κ promoter E-boxes.
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| 6. |
- McGrath, Sarah, et al.
(author)
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Correlation of Professional Antigen-Presenting Tbet+CD11c+ B Cells With Bone Destruction in Untreated Rheumatoid Arthritis
- 2024
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In: Arthritis & Rheumatology. - : John Wiley & Sons. - 2326-5191 .- 2326-5205.
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Journal article (peer-reviewed)abstract
- Objective: Subsets of CD21−/low memory B cells (MBCs), including double-negative (DN, CD27−IgD−) and Tbet+CD11c+ cells, are expanded in chronic inflammatory diseases. In rheumatoid arthritis (RA), CD21−/low MBCs correlate with joint destruction. However, whether this is due to the Tbet+CD11c+ subset, its function and pathogenic contribution to RA are unknown. This study aims to investigate the association between CD21−/lowTbet+CD11c+ MBCs and joint destruction as well as other clinical parameters and to elucidate their functional properties in patients with untreated RA (uRA). Methods: Clinical observations were combined with flow cytometry (n = 36) and single-cell RNA sequencing (scRNA-seq) and V(D)J sequencing (n = 4) of peripheral blood (PB) MBCs from patients with uRA. The transcriptome of circulating Tbet+CD11c+ MBCs was compared with scRNA-seq data of synovial B cells. In vitro coculture of Tbet+CD11c+ B cells with T cells was used to assess costimulatory capacity. Results: CD21−/lowTbet+CD11c+ MBCs in PB correlated with bone destruction but no other clinical parameters analyzed. The Tbet+CD11c+ MBCs have undergone clonal expansion and express somatically mutated V genes. Gene expression analysis of these cells identified a unique signature of more than 150 up-regulated genes associated with antigen presentation functions, including B cell receptor activation and clathrin-mediated antigen internalization; regulation of actin filaments, endosomes, and lysosomes; antigen processing, loading, presentation, and costimulation; a transcriptome mirrored in their synovial tissue counterparts. In vitro, Tbet+CD11c+ B cells induced retinoic acid receptor–related orphan nuclear receptor γT expression in CD4+ T cells, thereby polarizing to Th17 cells, a T cell subset critical for osteoclastogenesis and associated with bone destruction. Conclusion: This study suggests that Tbet+CD11c+ MBCs contribute to the pathogenesis of RA by promoting bone destruction through antigen presentation, T cell activation, and Th17 polarization. (Figure presented.).
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| 7. |
- Rosado, M. M., et al.
(author)
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From the fetal liver to spleen and gut: the highway to natural antibody
- 2009
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In: Mucosal Immunology. - : Elsevier BV. - 1933-0219. ; 2:4, s. 351-361
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Journal article (peer-reviewed)abstract
- The film of sIgA lining the intestinal epithelium plays a role in the regulation of the commensal microflora and prevention of pathogen invasion. We show that, in the absence of intentional immunization, all sIgA in the gut is produced by B-1a B cells. We also show that B-1a B cells and sIgA derive from lineage-negative precursors found in the fetal liver and located in the spleen after birth. The splenic precursors do not generate B cells of the adaptive immune system in bone marrow, spleen, and lymph nodes, but efficiently replenish the cells producing the natural antibodies. Therefore, B-1a B cells with their splenic progenitors and their progeny of plasma cells fill the same function of the primordial immune system of lower vertebrates. The natural antibodies in the serum and on the intestinal epithelium may be an evolutionary ancient tool for the immediate protection against commensal and pathogenic bacteria.
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