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Advances in Experimental Medicine and... 2020Since the identification of B cells in 1965 (Cooper et al. 1965), three has been tremendous progress in our understanding of B cell development, maturation and... (Review)
Review
Since the identification of B cells in 1965 (Cooper et al. 1965), three has been tremendous progress in our understanding of B cell development, maturation and function. A number of B cell subpopulations, including B-1, B-2 and regulatory B cells, have been identified. B-1 cells mainly originate from the fetal liver and contain B-1a and B-1b subsets. B-2 cells are derived from the bone marrow (BM) and can be further classified into follicular B (FOB) and marginal zone B (MZB) cells. Regulatory B cells (Bregs) function to suppress immune responses, primarily by production of the anti-inflammatory cytokine IL-10. B cell tolerance is established at several checkpoints, during B cell development in the BM (central tolerance) as well as during B cell maturation and activation in the periphery (peripheral tolerance). This chapter will focus on the regulation of important processes during the development and maturation of B-1 and B-2 cells.
Topics: Animals; B-Lymphocytes; Bone Marrow Cells; Humans; Immune Tolerance; Lymphocyte Activation; Peripheral Tolerance
PubMed: 32323265
DOI: 10.1007/978-981-15-3532-1_1 -
Nature Reviews. Drug Discovery Mar 2021In the past 15 years, B cells have been rediscovered to be not merely bystanders but rather active participants in autoimmune aetiology. This has been fuelled in part by... (Review)
Review
In the past 15 years, B cells have been rediscovered to be not merely bystanders but rather active participants in autoimmune aetiology. This has been fuelled in part by the clinical success of B cell depletion therapies (BCDTs). Originally conceived as a method of eliminating cancerous B cells, BCDTs such as those targeting CD20, CD19 and BAFF are now used to treat autoimmune diseases, including systemic lupus erythematosus and multiple sclerosis. The use of BCDTs in autoimmune disease has led to some surprises. For example, although antibody-secreting plasma cells are thought to have a negative pathogenic role in autoimmune disease, BCDT, even when it controls the disease, has limited impact on these cells and on antibody levels. In this Review, we update our understanding of B cell biology, review the results of clinical trials using BCDT in autoimmune indications, discuss hypotheses for the mechanism of action of BCDT and speculate on evolving strategies for targeting B cells beyond depletion.
Topics: Animals; Autoimmune Diseases; B-Lymphocytes; Clinical Trials as Topic; Humans; Lymphocyte Depletion
PubMed: 33324003
DOI: 10.1038/s41573-020-00092-2 -
Annual Review of Immunology Apr 2020The age-associated B cell subset has been the focus of increasing interest over the last decade. These cells have a unique cell surface phenotype and transcriptional... (Review)
Review
The age-associated B cell subset has been the focus of increasing interest over the last decade. These cells have a unique cell surface phenotype and transcriptional signature, and they rely on TLR7 or TLR9 signals in the context of Th1 cytokines for their formation and activation. Most are antigen-experienced memory B cells that arise during responses to microbial infections and are key to pathogen clearance and control. Their increasing prevalence with age contributes to several well-established features of immunosenescence, including reduced B cell genesis and damped immune responses. In addition, they are elevated in autoimmune and autoinflammatory diseases, and in these settings they are enriched for characteristic autoantibody specificities. Together, these features identify age-associated B cells as a subset with pivotal roles in immunological health, disease, and aging. Accordingly, a detailed understanding of their origins, functions, and physiology should make them tractable translational targets in each of these settings.
Topics: Aging; Animals; Autoimmunity; B-Lymphocyte Subsets; B-Lymphocytes; Biomarkers; Cytokines; Disease Susceptibility; Homeostasis; Humans; Immunologic Memory; Immunosenescence; Lymphocyte Activation
PubMed: 31986068
DOI: 10.1146/annurev-immunol-092419-031130 -
Immunological Reviews Sep 2021Immunological memory is a composite of lasting antibody titers maintained by plasma cells in conjunction with memory T and B cells. Memory B cells are a critical... (Review)
Review
Immunological memory is a composite of lasting antibody titers maintained by plasma cells in conjunction with memory T and B cells. Memory B cells are a critical reservoir for plasma cell generation in the secondary response. Identification of memory B cells requires that they be distinguished from naïve, activated, and germinal center precursors and from plasma cells. Memory B cells are heterogeneous in isotype usage, immunoglobulin mutational content, and phenotypic marker expression. Phenotypic subsets of memory B cells are defined by PD-L2, CD80, and CD73 expression in mice, by CD27 and FCRL4 expression in humans and by T-bet in both mice and humans. These subsets display marked functional heterogeneity, including the ability to rapidly differentiate into plasma cells versus seed germinal centers in the secondary response. Memory B cells are located in the spleen, blood, other lymphoid organs, and barrier tissues, and recent evidence indicates that some memory B cells may be dedicated tissue-resident populations. Open questions about memory B cell longevity, renewal and progenitor-successor relationships with plasma cells are discussed.
Topics: Animals; B-Lymphocytes; Germinal Center; Immunity, Humoral; Immunologic Memory; Mice; Plasma Cells
PubMed: 34396546
DOI: 10.1111/imr.13016 -
Viral Immunology May 2020Acute viral infections are characterized by rapid increases in viral load, leading to cellular damage and the resulting induction of complex innate and adaptive... (Review)
Review
Acute viral infections are characterized by rapid increases in viral load, leading to cellular damage and the resulting induction of complex innate and adaptive antiviral immune responses that cause local and systemic inflammation. Successful antiviral immunity requires the activation of many immune cells, including T cells, natural killer cells, and macrophages. B cells play a unique part through their production of antibodies that can both neutralize and clear viral particles before virus entry into a cell. Protective antibodies are produced even before the first exposure of a pathogen, through the regulated secretion of so-called natural antibodies that are generated even in the complete absence of prior microbial exposure. An early wave of rapidly secreted antibodies from extrafollicular (EF) responses draws on the preexisting naive or memory repertoire of B cells to induce a strong protective response that in kinetics tightly follows the clearance of acute infections, such as with influenza virus. Finally, the generation of germinal centers (GCs) provides long-term protection through production of long-lived plasma cells and memory B cells, which shape and broaden the B cell repertoire for more effective responses following repeat exposures. In this study, we review B cell responses to acute viral infections, primarily influenza virus, from the earliest nonspecific B-1 cell to early, antigen-specific EF responses and finally to GC responses. Throughout, we address known factors that lead to distinct B cell response outcomes and discuss how their functions effect viral clearance, highlighting the critical contributions of each response type to the induction of highly protective antiviral humoral immunity.
Topics: Animals; Antibodies, Viral; Antibody Formation; Antigen-Antibody Reactions; B-Lymphocytes; Germinal Center; Humans; Immunity, Humoral; Immunity, Innate; Influenza, Human; Mice; Orthomyxoviridae Infections; Virus Diseases
PubMed: 32326852
DOI: 10.1089/vim.2019.0207 -
Advances in Experimental Medicine and... 2020B cell development and activation are accompanied by dynamic genetic alterations including V(D)J rearrangements and immunoglobulin-gene somatic hypermutation and... (Review)
Review
B cell development and activation are accompanied by dynamic genetic alterations including V(D)J rearrangements and immunoglobulin-gene somatic hypermutation and class-switch recombination. Abnormalities in these genetic events can cause chromosomal translocations and genomic mutations, leading to altered expression and function of genes involved in B cell survival or proliferation and consequently B lymphomagenesis. In fact, B cell lymphoma accounts for 95% of the lymphomas. In this chapter, we summarize the morphology, immunophenotypes, clinical features, genetic defects that cause the malignancies, treatments, and prognosis of the most prevalent types of B cell lymphomas, including typical precursor B cell malignance (B-ALL/LBL) and mature B cell lymphoma (Hodgkin lymphoma and B cell non-Hodgkin lymphoma).
Topics: B-Lymphocytes; Humans; Immunoglobulin Class Switching; Lymphoma, B-Cell; Somatic Hypermutation, Immunoglobulin; Translocation, Genetic
PubMed: 32323276
DOI: 10.1007/978-981-15-3532-1_12 -
Advances in Experimental Medicine and... 2020Signaling through the B cell receptor (BCR) plays a critical role at multiple checkpoints of B cell biology. BCR acts as a gatekeeper of the progression of their early... (Review)
Review
Signaling through the B cell receptor (BCR) plays a critical role at multiple checkpoints of B cell biology. BCR acts as a gatekeeper of the progression of their early development in bone marrow (BM). It is also essential in triggering mechanisms such as clonal deletion and receptor editing to eliminate autoreactive B cells. In the periphery, it most importantly functions as a receptor that recognizes various extracellular antigens in response to bacterial and viral infections for conferring host defense. The recognition of antigens by BCR is the first step to receive T cell help for the functional differentiation of naive B cells toward plasma cells, germinal center (GC) B cells and memory B cells. In addition, similar to the role of BCR in the early stages of B cell development, BCR signaling plays a crucial role in the prevention of dysregulated activation of autoreactive B cells which can induce autoimmunity in the secondary lymphoid organs. Thus, since BCR is essential for the proper elicitation of immune responses by B cells, signaling through the BCR is tightly controlled by the intracellular positive and negative regulators. In this chapter, the mechanisms of activation and repression of BCR signaling are reviewed on the basis of the recent findings.
Topics: Animals; Autoimmunity; B-Lymphocytes; Humans; Lymphocyte Activation; Receptors, Antigen, B-Cell; Signal Transduction
PubMed: 32323266
DOI: 10.1007/978-981-15-3532-1_2 -
Frontiers in Immunology 2021B cells are central to the pathogenesis of multiple autoimmune diseases, through antigen presentation, cytokine secretion, and the production of autoantibodies. During... (Review)
Review
B cells are central to the pathogenesis of multiple autoimmune diseases, through antigen presentation, cytokine secretion, and the production of autoantibodies. During development and differentiation, B cells undergo drastic changes in their physiology. It is emerging that these are accompanied by equally significant shifts in metabolic phenotype, which may themselves also drive and enforce the functional properties of the cell. The dysfunction of B cells during autoimmunity is characterised by the breaching of tolerogenic checkpoints, and there is developing evidence that the metabolic state of B cells may contribute to this. Determining the metabolic phenotype of B cells in autoimmunity is an area of active study, and is important because intervention by metabolism-altering therapeutic approaches may represent an attractive treatment target.
Topics: Autoimmune Diseases; Autoimmunity; Autophagy; B-Lymphocytes; Biomarkers; Disease Susceptibility; Energy Metabolism; Humans; Lymphocyte Activation; Lymphopoiesis; Molecular Targeted Therapy
PubMed: 34163480
DOI: 10.3389/fimmu.2021.681105 -
Trends in Immunology Mar 2022During adaptive immunity, B cells differentiate either into memory B cells or plasma cells and produce antibodies against foreign antigens to fight infection.... (Review)
Review
During adaptive immunity, B cells differentiate either into memory B cells or plasma cells and produce antibodies against foreign antigens to fight infection. Additionally, they behave as antigen-presenting cells and participate in T cell activation during cellular immune responses. However, their functional dysregulation can result in various autoimmune diseases and cancers. With significant breakthroughs in single cell technologies, assessing individual B cell genomics, transcriptomics, and proteomics can give deeper insights into mammalian B cell development, differentiation, antibody repertoire, and responses under conditions of homeostasis, infection, and aberrations during disease. In this review, we discuss the adoption of single cell approaches to identify different B cell gene signatures and biomarkers in normal and diseased tissues, and subsequent benefits for future therapeutic discoveries.
Topics: Adaptive Immunity; Animals; Antigen-Presenting Cells; Antigens; B-Lymphocytes; Humans; Mammals; Plasma Cells
PubMed: 35090788
DOI: 10.1016/j.it.2022.01.003 -
Immunity Dec 2020Activated B cells participate in either extrafollicular (EF) or germinal center (GC) responses. Canonical responses are composed of a short wave of plasmablasts (PBs)... (Review)
Review
Activated B cells participate in either extrafollicular (EF) or germinal center (GC) responses. Canonical responses are composed of a short wave of plasmablasts (PBs) arising from EF sites, followed by GC producing somatically mutated memory B cells (MBC) and long-lived plasma cells. However, somatic hypermutation (SHM) and affinity maturation can take place at both sites, and a substantial fraction of MBC are produced prior to GC formation. Infection responses range from GC responses that persist for months to persistent EF responses with dominant suppression of GCs. Here, we review the current understanding of the functional output of EF and GC responses and the molecular switches promoting them. We discuss the signals that regulate the magnitude and duration of these responses, and outline gaps in knowledge and important areas of inquiry. Understanding such molecular switches will be critical for vaccine development, interpretation of vaccine efficacy and the treatment for autoimmune diseases.
Topics: Animals; Autoimmune Diseases; B-Lymphocyte Subsets; B-Lymphocytes; Germinal Center; Humans; Immunity; Immunoglobulin Class Switching; Infections; Lymphocyte Activation; Plasma Cells; Vaccines
PubMed: 33326765
DOI: 10.1016/j.immuni.2020.11.006