A checkpoint for autoreactivity in human IgM+ memory B cell development

Autoantibodies are removed from the repertoire at two checkpoints during B cell development in the bone marrow and the periphery. Despite these checkpoints, up to 20% of the antibodies expressed by mature naive B cells in healthy humans show low levels of self-reactivity. To determine whether self-reactive antibodies are also part of the antigen-experienced memory B cell compartment, we analyzed recombinant antibodies cloned from single circulating human IgM+ memory B cells. Cells expressing antibodies specific for individual bacterial polysaccharides were expanded in the IgM+ memory compartment. In contrast, B cells expressing self-reactive and broadly bacterially reactive antibodies were removed from the repertoire in the transition from naive to IgM+ memory B cell. Selection against self-reactive antibodies was implemented before the onset of somatic hypermutation. We conclude that a third checkpoint selects against self-reactivity during IgM+ memory B cell development in humans.

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STAT3 positively regulates an early step in B-cell development

Blood ◽

10.1182/blood-2006-05-024430 ◽

2006 ◽

Vol 108 (9) ◽

pp. 3005-3011 ◽

Cited By ~ 51

Author(s):

Wei-Chun Chou ◽

David E. Levy ◽

Chien-Kuo Lee

Keyword(s):

B Cells ◽

B Cell ◽

Progenitor Cells ◽

Cell Development ◽

B Cell Development ◽

B Lymphopoiesis ◽

Cell Compartment ◽

Immature B Cells ◽

A Cell ◽

Deficient Mice

Abstract Transcription factors are critical for instructing the development of B lymphocytes from multipotential progenitor cells in the bone marrow (BM). Here, we show that the absence of STAT3 impaired B-cell development. Mice selectively lacking STAT3 in BM progenitor cells displayed reduced numbers of mature B cells, both in the BM and in the periphery. The reduction in the B-cell compartment included reduced percentages and numbers of pro-B, pre-B, and immature B cells in the absence of STAT3, whereas the number of pre–pro-B cells was increased. We found that pro-B and pre-B–cell populations lacking STAT3 were hyporesponsive to IL-7 because of a decreased number of IL-7–responsive cells rather than decreased expression or signaling of IL-7Rα. Moreover, STAT3-deficient mice displayed enhanced apoptosis in the pro-B population when deprived of survival factors, suggesting that at least 2 mechanisms (impaired differentiation and enhanced apoptosis) are involved in the mutant phenotype. Last, BM transplantation confirmed that impaired B lymphopoiesis in the absence of STAT3 was caused by a cell autonomous defect. In sum, these studies defined a specific role for STAT3 in early B-cell development, probably acting at the pre–pro-B transition by contributing to the survival of IL-7–responsive progenitors.

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Persistent expression of autoantibodies in SLE patients in remission

Journal of Experimental Medicine ◽

10.1084/jem.20061446 ◽

2006 ◽

Vol 203 (10) ◽

pp. 2255-2261 ◽

Cited By ~ 105

Author(s):

Sergey Yurasov ◽

Thomas Tiller ◽

Makoto Tsuiji ◽

Klara Velinzon ◽

Virginia Pascual ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Lupus Erythematosus ◽

Clinical Remission ◽

B Cell Development ◽

Cell Compartment ◽

Healthy Humans ◽

Polyreactive Antibodies ◽

Integral Feature ◽

Active Disease

A majority of the antibodies expressed by nascent B cells in healthy humans are self-reactive, but most of these antibodies are removed from the repertoire during B cell development. In contrast, untreated systemic lupus erythematosus (SLE) patients fail to remove many of the self-reactive and polyreactive antibodies from the naive repertoire. Here, we report that SLE patients in clinical remission continue to produce elevated numbers of self-reactive and polyreactive antibodies in the mature naive B cell compartment, but the number of B cells expressing these antibodies is lower than in patients with active disease. Our finding that abnormal levels of self-reactive mature naive B cells persist in the majority of patients in clinical remission suggests that early checkpoint abnormalities are an integral feature of SLE.

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Enforced Expression of Bcl-2 Selectively Perturbs Negative Selection of Dual Reactive Antibodies

Developmental Immunology ◽

10.1155/2001/83595 ◽

2001 ◽

Vol 8 (3-4) ◽

pp. 223-234 ◽

Cited By ~ 6

Author(s):

Evangelia Notidis ◽

Shailaja Hande ◽

Tim Manser

Keyword(s):

B Cells ◽

B Cell ◽

Negative Selection ◽

Somatic Hypermutation ◽

Serum Antibody ◽

Affinity Maturation ◽

Peripheral Tolerance ◽

Cell Compartment ◽

Memory B Cell ◽

Selection Of

We investigated the role of apoptosis in the development of B cell memory by analyzing the (p-azophenylarsonate) Ars response in a line of A strain mice in which expression of human Bcl-2 was enforced in the B cell compartment. Previous studies of the Ars immune response in these A. Bcl-2 mice, demonstrated that a large percentage of the antibodies expressed by the Ars induced memory B cell compartment had accumulated point mutations via somatic hypermutation that increased their affinity for both Ars and the autoantigen DNA (“dual reactive” antibodies). This was in sharp contrast to normal A strain mice which displayed no dual reactive B cells in their Ars induced memory B cell compartment. These data suggested that interference with apoptotic pathways regulated by Bcl-2 allows developing memory B cells that have acquired autoreactivity to bypass a peripheral tolerance checkpoint. Further studies of these mice, reported here, demonstrate that enforced expression of Bcl-2 does not alter serum antibody affinity maturation nor positive selection of B cells expressing somatically mutated antibody with an increased affinity for Ars. Moreover, the somatic hypermutation process was unaffected in A. Bcl-2 mice. Thus, enforced expression of Bcl-2 in A. Bcl-2 mice appears to selectively alter a negative selection process that operates during memory B cell differentiation.

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The human fetal omentum: a site of B cell generation.

Journal of Experimental Medicine ◽

10.1084/jem.175.2.397 ◽

1992 ◽

Vol 175 (2) ◽

pp. 397-404 ◽

Cited By ~ 89

Author(s):

N Solvason ◽

J F Kearney

Keyword(s):

B Cells ◽

B Cell ◽

Fetal Liver ◽

Cell Development ◽

B Cell Development ◽

Primary Site ◽

Cell Compartment ◽

Fetal Mouse ◽

Time Period ◽

A Site

The fetal mouse omentum has been shown to be a source of precursors that exclusively reconstitutes Ly1+ B cells and the closely related Ly1- sister population, but not conventional B cells or T cells. We have extended these studies to compare B cell development in the human fetal omentum, liver, and spleen, and to demonstrate that the pro/pre-B cell compartment (CD24+, sIgM-) is detected in the omentum and liver but not spleen as early as 8 wk of gestation. From 8 to 12 wk of gestation, the proportions of IgM+ cells that were pre-B cells (cIgM+/sIgM-) in the omentum and liver were 53 +/- 15% and 45 +/- 13%, respectively, and IgM+ cells were not detectable in the spleen. After 12 wk, the percentage of pre-B cells was unchanged in the fetal liver (41 +/- 10%) but decreased significantly in the omentum (25 +/- 14%); pre-B cells were now detected in the spleen but at much lower percentages (2 +/- 3%) than either the omentum or liver. The nuclear enzyme, Tdt, was detected in approximately 25% of the CD24+ cells in the omentum and liver during the 8-12-wk time period, however, Tdt+ cells were not detected in the spleen. Approximately 40% of the mature B cells found in the omentum and spleen were CD5+ compared with only 20% in the liver. These results demonstrate that the fetal omentum, like the fetal liver and bone marrow, is a primary site of B cell development.

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Monoclonal antibody to an IgD allotype induces a new type of allotype suppression in the mouse.

Journal of Experimental Medicine ◽

10.1084/jem.154.3.921 ◽

1981 ◽

Vol 154 (3) ◽

pp. 921-934 ◽

Cited By ~ 13

Author(s):

T Tokuhisa ◽

F T Gadus ◽

L A Herzenberg ◽

L A Herzenberg

Keyword(s):

Monoclonal Antibody ◽

B Cells ◽

B Cell ◽

Early Adulthood ◽

Cell Development ◽

B Cell Development ◽

Cell Populations ◽

Perinatal Exposure ◽

Memory B Cell ◽

New Type

Studies presented here show that perinatal exposure to anti-IgD allotype antibodies induces a persistant IgG-allotype suppression in the mouse that differs markedly from either the short-term or chronic allotype suppressions induced by antibodies to IgG or IgM allotypes. This novel form of allotype suppression induced by injecting neonatal BALB/c x SJL mice with monoclonal antibody to the paternal Igh-5b (IgD) allotype drastically reduces paternal allotype production during the first 6 mo of the affected animal's life and simultaneously stimulates compensatory production of maternal allotype IgG. In addition, it interferes with the development of B cells carrying the paternal IgD allotype and impairs the development of memory B cells destined to give rise to paternal allotype IgG-producing cells. Thus, its properties make it more like allotype suppression as described in the rabbit than like the known forms of allotype suppression in the mouse. As shown here, Igh-5b-bearing (5b+) B cells are completely depleted from the neonate after anti-5b exposure and only gradually appear as the animal ages. The recovery of the 5b+ population to near normal size (by approximately 14 wk of age) substantially preceeds recovery of the ability to generate normal-size memory B cell populations. Paternal allotype levels in serum remain well below normal until the anti-5b-exposed animals reach approximately 6 mo of age and then climb rapidly, finally stabilizing at levels comparable to levels in controls of the same age. The elevated maternal allotype levels characteristic of the suppression period began falling somewhat earlier and are clearly stabilized within the normal range in 6-mo-old animals. Thus, perinatal exposure to anti-5b compromises B cell development and IgG production throughout early adulthood but has little apparent effect in older animals. Perinatal exposure to antibody to the paternal IgG2a allotype (Igh-1b) or IgM allotype (Igh-6b), in contrast, induces a chronic allotype suppression that has relatively little affect on IgG production in young adults but severely suppresses allotype production in older animals. Furthermore, this type of (chronic) suppression does not influence maternal allotype production and does not interfere with memory B cell development. These differences, illustrated here by data from parallel sets of animals exposed either toi anti-5b or anti-1b, raise a series of intriguing questions concerning the mechanisms regulating B cell development and expression and the nature of the neonatal (B) cell populations with which the suppression-inducing antibodies react.

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IgG1 B cell receptor signaling is inhibited by CD22 and promotes the development of B cells whose survival is less dependent on Igα/β

Journal of Experimental Medicine ◽

10.1084/jem.20062024 ◽

2007 ◽

Vol 204 (4) ◽

pp. 747-758 ◽

Cited By ~ 87

Author(s):

Ari Waisman ◽

Manfred Kraus ◽

Jane Seagal ◽

Snigdha Ghosh ◽

Doron Melamed ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Cell Receptor ◽

Cell Development ◽

B Cell Development ◽

B Cell Receptor ◽

Cell Physiology ◽

Cell Compartment ◽

Heavy Chains

We describe a mouse strain in which B cell development relies either on the expression of membrane-bound immunoglobulin (Ig) γ1 or μ heavy chains. Progenitor cells expressing γ1 chains from the beginning generate a peripheral B cell compartment of normal size with all subsets, but a partial block is seen at the pro– to pre–B cell transition. Accordingly, γ1-driven B cell development is disfavored in competition with developing B cells expressing a wild-type (WT) IgH locus. However, the mutant B cells display a long half-life and accumulate in the mature B cell compartment, and even though partial truncation of the Igα cytoplasmic tail compromises their development, it does not affect their maintenance, as it does in WT cells. IgG1-expressing B cells showed an enhanced Ca2+ response upon B cell receptor cross-linking, which was not due to a lack of inhibition by CD22. The enhanced Ca2+ response was also observed in mature B cells that had been switched from IgM to IgG1 expression in vivo. Collectively, these results suggest that the γ1 chain can exert a unique signaling function that can partially replace that of the Igα/β heterodimer in B cell maintenance and may contribute to memory B cell physiology.

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The Dual Bromodomain Protein Brd2 Controls Primary B Cell Mitogenesis and Cell Cycle in Mice Reconstituted with Lentivirus-Transduced HSCs

Blood ◽

10.1182/blood.v112.11.2465.2465 ◽

2008 ◽

Vol 112 (11) ◽

pp. 2465-2465

Author(s):

Wanda P. Blanton ◽

Fangnian Wang ◽

Hongsheng Liu ◽

Paul Romesser ◽

Douglas Faller ◽

...

Keyword(s):

Cell Cycle ◽

Stem Cells ◽

Bone Marrow ◽

B Cells ◽

B Cell ◽

Cell Development ◽

B Cell Development ◽

Brdu Incorporation ◽

Cell Compartment ◽

Hematopoietic Stem

Abstract Transcriptional control of cellular proliferation and differentiation is critically important in hematopoiesis; specifically, the role of chromatin-dependent regulatory processes in this context is poorly understood. The human BRD2 proto-oncogene encodes a double bromodomain protein that binds to acetylated histone H4 in chromatin and is located within the MHC class II locus, suggesting Brd2 plays a role in immunity. However, BRD2 shares no sequence similarity with other MHC genes, nor is Brd2 involved in antigen processing, but rather it plays a role in mitogenic signal transduction. We have previously found that whole-body knockout of Brd2 is lethal to mice. However, when Brd2 was expressed constitutively in the B cells of transgenic mice, Brd2 binds E2F proteins, histone acetylases and Swi/Snf complexes, and co-activates cyclin A leading to B cell lymphoma and leukemia. Importantly, elevated levels of Brd2 have been reported in primary malignant B cells from human and mouse. We therefore hypothesize that Brd2 multiprotein complexes, working through chromatin modification, are crucial in the control of the cell cycle and in the mitogen responsiveness and proliferation of the B cell compartment. To study the effects of Brd2 in B cell development and proliferation, we performed bone marrow transplants of hematopoietic stem cells in a chimeric mouse model. Hematopoietic stem cells were sorted from CD45.1 donor mice with the characteristic ‘side population’ profile by flow cytometry and transduced with lentivirus containing vectors for Brd2 overexpression, shRNA knockdown, or control vectors. Recipient CD45.2 mice were lethally irradiated and a functional immune system was successfully reconstituted with donor cells and CD45.2 competitor BM cells. Mice were immunophenotyped and functional B cell mitogenic capacity was examined by BrdU incorporation into LPS-stimulated B cells. We found that in the spleen, Brd2 expression dramatically expands the CD45.1 (but not CD45.2) B cell compartment at the expense of T cells and renders B cells mitogenically hypersensitive. Compared with control, there was an increase in BrdU incorporation at 24 and 48 hours (29.8% v. 43.5% at T=24 h; 56.9% v. 66.7% at T=48 h). Preliminary results also suggest that B cell development was skewed in the bone marrow and periphery towards B1a phenotype. Moreover, downregulation of Brd2 via shRNA blocked cyclin A transcription and completely arrested B cell development and proliferation. Taken together, these data suggest that Brd2, through epigenetic regulation of the cell cycle, plays an important role in B-lymphopoiesis, proliferation, and stimulation.

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Metabolic determinants of B-cell selection

Biochemical Society Transactions ◽

10.1042/bst20201316 ◽

2021 ◽

Author(s):

Lai N. Chan ◽

Eamon Aghania ◽

Etienne Leveille ◽

Markus Müschen

Keyword(s):

Immune System ◽

B Cells ◽

Autoimmune Disease ◽

B Cell ◽

Cell Development ◽

B Cell Development ◽

Common Mechanism ◽

Cell Selection ◽

Immunoglobulin Gene ◽

Adaptive Immune

B-cells are antibody-producing cells of the adaptive immune system. Approximately 75% of all newly generated B-cells in the bone marrow are autoreactive and express potentially harmful autoantibodies. To prevent autoimmune disease, the immune system has evolved a powerful mechanism to eliminate autoreactive B-cells, termed negative B-cell selection. While designed to remove autoreactive clones during early B-cell development, our laboratory recently discovered that transformed B-cells in leukemia and lymphoma are also subject to negative selection. Indeed, besides the risk of developing autoimmune disease, B-cells are inherently prone to malignant transformation: to produce high-affinity antibodies, B-cells undergo multiple rounds of somatic immunoglobulin gene recombination and hypermutation. Reflecting high frequencies of DNA-breaks, adaptive immune protection by B-cells comes with a dramatically increased risk of development of leukemia and lymphoma. Of note, B-cells exist under conditions of chronic restriction of energy metabolism. Here we discuss how these metabolic gatekeeper functions during B-cell development provide a common mechanism for the removal of autoreactive and premalignant B-cells to safeguard against both autoimmune diseases and B-cell malignancies.

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