Monocytoid B cells: An Enigmatic B cell Subset Showing Evidence of Extrafollicular Immunoglobulin gene Somatic Hypermutation

A minor subset of individuals infected with HIV-1 develop antibody neutralization breadth during the natural course of the infection, often linked to chronic, high-level viremia. Despite significant efforts, vaccination strategies have been unable to induce similar neutralization breadth and the mechanisms underlying neutralizing antibody induction remain largely elusive. Broadly neutralizing antibody responses can also be found in individuals who control HIV to low and even undetectable plasma levels in the absence of antiretroviral therapy, suggesting that high antigen exposure is not a strict requirement for neutralization breadth. We therefore performed an analysis of paired heavy and light chain B-cell receptor (BCR) repertoires in 12,591 HIV-1 envelope-specific single memory B-cells to determine alterations in the BCR immunoglobulin gene repertoire and B-cell clonal expansions that associate with neutralizing antibody breadth in 22 HIV controllers. We found that the frequency of genomic mutations in IGHV and IGLV was directly correlated with serum neutralization breadth. The repertoire of the most mutated antibodies was dominated by a small number of large clones with evolutionary signatures suggesting that these clones had reached peak affinity maturation. These data demonstrate that even in the setting of low plasma HIV antigenemia, similar to what a vaccine can potentially achieve, BCR selection for extended somatic hypermutation and clonal evolution can occur in some individuals suggesting that host-specific factors might be involved that could be targeted with future vaccine strategies.

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Human germinal center B cells express the apoptosis-inducing genes Fas, c-myc, P53, and Bax but not the survival gene bcl-2.

Journal of Experimental Medicine ◽

10.1084/jem.183.3.971 ◽

1996 ◽

Vol 183 (3) ◽

pp. 971-977 ◽

Cited By ~ 156

Author(s):

H Martinez-Valdez ◽

C Guret ◽

O de Bouteiller ◽

I Fugier ◽

J Banchereau ◽

...

Keyword(s):

Cell Cycle ◽

B Cells ◽

B Cell ◽

Germinal Center ◽

Somatic Hypermutation ◽

Cell Subset ◽

Variable Region ◽

Negative Regulator ◽

Memory B Cell ◽

Survival Gene

During T cell-dependent antibody responses, B cells within germinal centers (GC) alter the affinity of their antigen receptor by introducing somatic mutations into variable region of immunoglobulin (IgV) genes. During this process, GC B cells are destined to die unless positively selected by antigens and CD40-ligand. To understand survival/death control of germinal center B cell, the expression of four apoptosis-inducing genes, Fas, c-myc, Bax, and P53, together with the survival gene bcl-2, has been analyzed herein among purified tonsillar naive, GC, and memory B cells. IgD+CD38- naive B cells were separated into CD23- (mature B cell [Bm]1) subset and CD23+ (Bm2), IgD-CD38+ GC B cells were separated into subsets of CD77+ centroblasts (Bm3) and CD77- centrocytes (Bm4), whereas IgD-CD38- cells represented the Bm5 memory B cell subset. Sequence analysis of IgV region genes indicated that somatic hypermutation was triggered in the Bm3 centroblast subset. Here we show that bcl-2 is only detectable with naive (Bm1 and 2) and memory B cell (Bm5) subsets, whereas all four apoptosis-inducing genes were most significantly expressed within GC B cells. Fas was equally expressed in Bm3 centroblasts and Bm4 centrocytes, whereas Bax was most significantly expressed in Bm4 centrocytes. c-myc, a positive regulator of cell cycle, was most significantly expressed in proliferating Bm3 centroblasts, whereas P53, a negative regulator of cell cycle, was most signficantly expressed in nonproliferating Bm4 centrocytes. The present results indicate that the survival/death of GC B cells are regulated by the up- and downregulation of multiple genes, among which the expression of c-myc and P53 in the absence of bcl-2 may prime the proliferating Bm3 centroblasts and nonproliferating Bm4 centrocytes to apoptosis.

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AID expression identifies interfollicular large B cells as putative precursors of mature B-cell malignancies

Blood ◽

10.1182/blood-2005-06-2502 ◽

2006 ◽

Vol 107 (6) ◽

pp. 2470-2473 ◽

Cited By ~ 27

Author(s):

Gerhard Moldenhauer ◽

Sergey W. Popov ◽

Beate Wotschke ◽

Silke Brüderlein ◽

Petra Riedl ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Cytidine Deaminase ◽

Class Switch Recombination ◽

Cell Subset ◽

Germinal Centers ◽

Immunoglobulin Gene ◽

B Cell Malignancies ◽

Class Switch ◽

Thymic Medulla

Abstract Neoplastic transformation of mature B cells can be triggered by class-switch recombination of the immunoglobulin gene, which aberrantly targets a protooncogene and promotes translocation. Class-switch recombination is initiated by the B-cell-specific protein activation-induced cytidine deaminase (AID). Using immunohistochemistry with a newly generated monoclonal antibody and quantitative reverse-transcription-polymerase chain reaction (RT-PCR) on microdissected tissue from lymph node, tonsil, and thymus, we demonstrate that AID expression is found in secondary lymphoid organs outside germinal centers and in the thymic medulla at substantial levels. This is accompanied by the presence of circle transcripts, indicating class-switch recombination to be active at these sites. The dominant AID-expressing cell population outside germinal centers displays cytomorphologic properties corresponding to those that define the recently characterized interfollicular large B-cell subset. These findings indicate that interfollicular large B cells and AID-expressing B lymphocytes of the thymic medulla could give rise to mature B-cell malignancies. (Blood. 2006;107:2470-2473)

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A unique B2 B cell subset in the intestine

Journal of Experimental Medicine ◽

10.1084/jem.20071572 ◽

2008 ◽

Vol 205 (6) ◽

pp. 1343-1355 ◽

Cited By ~ 29

Author(s):

Yasuyo Shimomura ◽

Atsuhiro Ogawa ◽

Mayumi Kawada ◽

Ken Sugimoto ◽

Emiko Mizoguchi ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Intestinal Inflammation ◽

Somatic Hypermutation ◽

Alternative Pathway ◽

Cell Subset ◽

Immunoglobulin M ◽

Lymphoid Tissues ◽

Dependent Manner ◽

Cell Pool

Over 80% of the body's activated B cells are located in mucosal sites, including the intestine. The intestine contains IgM+ B cells, but these cells have not been characterized phenotypically or in terms of their developmental origins. We describe a previously unidentified and unique subset of immunoglobulin M+ B cells that present with an AA4.1−CD21−CD23− major histocompatibility complex class IIbright surface phenotype and are characterized by a low frequency of somatic hypermutation and the potential ability to produce interleukin-12p70. This B cell subset resides within the normal mucosa of the large intestine and expands in response to inflammation. Some of these intestinal B cells originate from the AA4.1+ immature B2 cell pool in the steady state and are also recruited from the recirculating naive B cell pool in the context of intestinal inflammation. They develop in an antigen-independent and BAFF-dependent manner in the absence of T cell help. Expansion of these cells can be induced in the absence of the spleen and gut-associated lymphoid tissues. These results describe the existence of an alternative pathway of B cell maturation in the periphery that gives rise to a tissue-specific B cell subset.

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The Normal IGHV1-69-derived B Cell Repertoire Contains “Stereotypic” Patterns Characteristic of Unmutated CLL.

Blood ◽

10.1182/blood.v114.22.4370.4370 ◽

2009 ◽

Vol 114 (22) ◽

pp. 4370-4370

Author(s):

Francesco Forconi ◽

Kathleen N Potter ◽

Isla Wheatley ◽

Nikos Darzentas ◽

Elisa Sozzi ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Conflicts Of Interest ◽

Cell Subset ◽

Lymphocytic Leukemia ◽

Immunoglobulin Gene ◽

Cell Of Origin ◽

Cell Repertoire ◽

B Cell Repertoire ◽

Germinal Center B Cell

Abstract Abstract 4370 The cell of origin of chronic lymphocytic leukemia (CLL) has long been sought and immunoglobulin gene analysis provides new clues. The immunoglobulin heavy variable gene (IGHV) status has clinical relevance in CLL, where two subsets, delineated by the absence or presence of somatic mutation, have markedly different prognoses. The unmutated subset (U-CLL), of inferior prognosis, appears to derive from a pre-germinal center B cell. In U-CLL, there is strikingly increased usage of the 51p1-related alleles of the IGHV1-69 gene, often combined with selected IGHD genes and with IGHJ6. Shared sequence “stereotypic” characteristics of the HCDR3 result, and suggest antigen selection of the leukemic clones. In this study, we have analyzed 147 51p1/IGHJ6 rearrangements from 3 healthy individuals (>51yr) and sought sequence patterns parallel to those of U-CLL. A pre-established dataset of 313 51p1/IGHJ6 rearrangements from patients with U-CLL was used as a reference. A high proportion (49/147, 33.3%) of normal sequences revealed stereotypic patterns, several (22/147, 15%) being similar to those described in U-CLL. Additional CLL-associated stereotypes, not yet reported, were detected in 7/147 sequences (4.8%). Stereotypes (13.6%) not detected in CLL were also found in 20/147 (13.6%) 51p1/IGHJ6 combinations. The HCDR2-IGHJ6 sequences were almost exclusively unmutated (143/147, 97,3% sequences had ≥98% homology to germline). Junctional amino acids in normal B cells were heterogeneous, as in the cases of CLL with stereotyped 51p1/IGHJ6 B-cell receptors. Normal B cells expressing 51p1-derived IgM (4.8% of all B-cells) had a phenotype of naïve B-cells, similar to 51p1-negative (CD27-) B cells, i.e. IgM+ IgD+ CD23+ CD38+, with a small percentage of CD5+ B cells, not found in the memory B-cell subset. This snapshot of the naïve B-cell repertoire reveals subsets of B cells closely related to those characteristic of CLL. Conserved patterns in the 51p1-encoded IgM of normal B cells suggest a restricted sequence repertoire shaped by evolution to recognize common pathogens. Proliferative pressure on these cells is the likely route to U-CLL. Disclosures: No relevant conflicts of interest to declare.

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Distinct clonal evolution of B-cells in HIV controllers with neutralizing antibody breadth

10.1101/2020.09.02.277566 ◽

2020 ◽

Author(s):

Deniz Cizmeci ◽

Giuseppe Lofano ◽

Anne-Sophie Dugast ◽

Dongkyoon Kim ◽

Guy Cavet ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Somatic Hypermutation ◽

Clonal Evolution ◽

Neutralizing Antibody ◽

Affinity Maturation ◽

Gene Repertoire ◽

Immunoglobulin Gene ◽

Hiv Controllers ◽

Hiv 1

AbstractA minor subset of individuals infected with HIV-1 develop antibody neutralization breadth during the natural course of the infection, often linked to chronic, high level viremia. Despite significant efforts, vaccination strategies have been unable to induce similar neutralization breadth and the mechanisms underlying neutralizing antibody induction remain largely elusive. Broadly neutralizing antibody responses can also be found in individuals who control HIV to low and even undetectable plasma levels in the absence of antiretroviral therapy, suggesting that high antigen exposure is not a strict requirement for neutralization breadth. We therefore performed an analysis of paired heavy and light chain B-cell receptor repertoires in 12,591 HIV-1 Envelope-specific single memory B-cells to determine alterations in the BCR immunoglobulin gene repertoire and B-cell clonal expansions that associate with neutralizing antibody breadth in 22 HIV controllers. We found that the frequency of genomic mutations in IGHV and IGLV was directly correlated with serum neutralization breadth. The repertoire of the most mutated antibodies was dominated by a small number of large clones with evolutionary signatures suggesting that these clones had reached peak affinity maturation. These data demonstrate that even in the setting of low plasma HIV antigenemia, similar to what a vaccine can potentially achieve, BCR selection for extended somatic hypermutation and clonal evolution can occur in some individuals suggesting that host-specific factors might be involved that could be targeted with future vaccine strategies.

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Hyper‐metabolic B cells in the spleens of old mice make antibodies with autoimmune specificities

Immunity & Ageing ◽

10.1186/s12979-021-00222-3 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Daniela Frasca ◽

Maria Romero ◽

Denisse Garcia ◽

Alain Diaz ◽

Bonnie B. Blomberg

Keyword(s):

B Cells ◽

B Cell ◽

Inflammatory Markers ◽

Cell Subset ◽

Antibody Responses ◽

Metabolic Phenotype ◽

Cellular Mechanisms ◽

Autoimmune Antibodies ◽

B Cell Subsets ◽

Old Mice

Abstract Background Aging is associated with increased intrinsic B cell inflammation, decreased protective antibody responses and increased autoimmune antibody responses. The effects of aging on the metabolic phenotype of B cells and on the metabolic programs that lead to the secretion of protective versus autoimmune antibodies are not known. Methods Splenic B cells and the major splenic B cell subsets, Follicular (FO) and Age-associated B cells (ABCs), were isolated from the spleens of young and old mice and left unstimulated. The RNA was collected to measure the expression of markers associated with intrinsic inflammation and autoimmune antibody production by qPCR. B cells and B cell subsets were also stimulated with CpG and supernatants collected after 7 days to measure autoimmune IgG secretion by ELISA. Metabolic measures (oxygen consumption rate, extracellular acidification rate and glucose uptake) were performed using a Seahorse XFp extracellular flux analyzer. Results Results have identified the subset of ABCs, whose frequencies and numbers increase with age and represent the most pro-inflammatory B cell subset, as the cell type mainly if not exclusively responsible for the expression of inflammatory markers and for the secretion of autoimmune antibodies in the spleen of old mice. Hyper-inflammatory ABCs from old mice are also hyper-metabolic, as compared to those from young mice and to the subset of FO B cells, a feature needed not only to support their higher expression of RNA for inflammatory markers but also their higher autoimmune antibody secretion. Conclusions These results identify a relationship between intrinsic inflammation, metabolism and autoimmune B cells and suggest possible ways to understand cellular mechanisms that lead to the generation of pathogenic B cells, that are hyper-inflammatory and hyper-metabolic, and secrete IgG antibodies with autoimmune specificities.

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OP0186 CHANGES IN CIRCULATING B CELL LEVELS AND IMMUNOPHENOTYPE ARE ASSOCIATED WITH DEVELOPMENT OF ARTHRITIS FOLLOWING TREATMENT WITH CHECKPOINT INHIBITORS

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2021-eular.908 ◽

2021 ◽

Vol 80 (Suppl 1) ◽

pp. 112.2-113

Author(s):

M. Gatto ◽

S. Bjursten ◽

C. Jonell ◽

C. Jonsson ◽

S. Mcgrath ◽

...

Keyword(s):

Flow Cytometry ◽

B Cells ◽

Adverse Events ◽

B Cell ◽

Mononuclear Cells ◽

Checkpoint Inhibitors ◽

Therapy Monitoring ◽

Cell Subset ◽

Peripheral Blood Mononuclear ◽

Transitional B Cells

Background:Inflammatory arthritis (IA) is frequent among rheumatic side effects induced by checkpoint inhibitor (CPI) therapy for metastatic malignancies1. While T cells are likely to sustain the inflammatory process2, fewer data are available concerning the role of B cells3.Objectives:To investigate the phenotype of circulating B cells in patients who develop CPI-induced IA (CPI-IA) and to compare it with features of B cells in patients not developing immune-related adverse events (irAE) upon CPI treatment.Methods:B cell subsets at baseline (before CPI initiation) and during CPI treatment were analyzed in CPI-IA patients and in patients receiving CPI but who did not develop irAE (non-irAE). Peripheral blood mononuclear cells (PBMC) were analyzed by flow cytometry and B cells were identified as CD19+ and divided into naïve (CD27-IgD+), memory (CD27+IgD+/-), double negative (CD27-IgD-) and transitional (CD10+CD24+CD38+/hi) B cells. Levels of CD21, an activation marker on transitional B cells, were also analyzed. Non-parametric tests were used for analysis of differences between groups.Results:Six CPI-IA and 7 non-irAE patients matched for age, gender and CPI treatment were included, who had received CPI treatment due to metastatic melanoma. Flow cytometry revealed a significant increase of circulating B cells (p=0.002) (Figure 1A) and especially of transitional B cells in CPI-IA patients vs. non-irAE (median %, range: 7.8 (4.5-11.4) vs. 3.2 (1.6-4.3),p=0.007) (Figure 1B), while no remarkable changes were seen across other subsets. Transitional B cell levels significantly decreased from active to quiescent CPI-IA in all patients (p=0.008). In two CPI-IA patients for whom baseline sampling was available, the increase of transitional levels occurred early after CPI treatment and before CPI-IA onset. Levels of expression of CD21 on transitional B cells were increased in CPI-IA vs. non-irAE (p=0.01).Conclusion:Transitional B cells are expanded in CPI-IA patients and seem to increase early after start of CPI therapy. Monitoring this B cell subset might lead to closer follow-up and earlier diagnosis of CPI-IA.References:[1]Ramos-Casals M, Brahmer JR, Callahan MK, et al. Immune-related adverse events of checkpoint inhibitors. Nat Rev Dis Primers 2020;6:38[2]Murray-Brown W, Wilsdon TD, Weedon H, et al. Nivolumab-induced synovitis is characterized by florid T cell infiltration and rapid resolution with synovial biopsy-guided therapy. J Immunother Cancer 2020;8:e000281[3]Das R, Bar N, Ferreira M, et al. Early B cell changes predict autoimmunity following combination immune checkpoint blockade. J Clin Invest. 2018;128:715-2Disclosure of Interests:None declared

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Inactivating SOCS1 mutations are caused by aberrant somatic hypermutation and restricted to a subset of B-cell lymphoma entities

Blood ◽

10.1182/blood-2009-06-225839 ◽

2009 ◽

Vol 114 (20) ◽

pp. 4503-4506 ◽

Cited By ~ 81

Author(s):

Anja Mottok ◽

Christoph Renné ◽

Marc Seifert ◽

Elsie Oppermann ◽

Wolf Bechstein ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Cell Lymphoma ◽

Somatic Hypermutation ◽

B Cell Lymphoma ◽

Rare Mutations ◽

Large B Cell Lymphoma ◽

Mantle Cell ◽

Follicular Lymphomas ◽

Large B Cell

Abstract STATs are constitutively activated in several malignancies. In primary mediastinal large B-cell lymphoma and Hodgkin lymphoma (HL), inactivating mutations in SOCS1, an inhibitor of JAK/STAT signaling, contribute to deregulated STAT activity. Based on indications that the SOCS1 mutations are caused by the B cell–specific somatic hypermutation (SHM) process, we analyzed B-cell non-HL and normal B cells for mutations in SOCS1. One-fourth of diffuse large B-cell lymphoma and follicular lymphomas carried SOCS1 mutations, which were preferentially targeted to SHM hotspot motifs and frequently obviously inactivating. Rare mutations were observed in Burkitt lymphoma, plasmacytoma, and mantle cell lymphoma but not in tumors of a non–B-cell origin. Mutations in single-sorted germinal center B cells were infrequent relative to other genes mutated as byproducts of normal SHM, indicating that SOCS1 inactivation in primary mediastinal large B-cell lymphoma, HL, diffuse large B-cell lymphoma, and follicular lymphoma is frequently the result of aberrant SHM.

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CD5+/Mac-1− peritoneal B cells: A novel B cell subset that exhibits characteristics of B-1 cells

Immunology Letters ◽

10.1016/j.imlet.2006.01.002 ◽

2006 ◽

Vol 105 (1) ◽

pp. 90-96 ◽

Cited By ~ 24

Author(s):

W HASTINGS ◽

S GURDAK ◽

J TUMANG ◽

T ROTHSTEIN

Keyword(s):

B Cells ◽

B Cell ◽

Cell Subset

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