scholarly journals Overexpression of T-bet in HIV infection is associated with accumulation of B cells outside germinal centers and poor affinity maturation

2019 ◽  
Vol 11 (520) ◽  
pp. eaax0904 ◽  
Author(s):  
James W. Austin ◽  
Clarisa M. Buckner ◽  
Lela Kardava ◽  
Wei Wang ◽  
Xiaozhen Zhang ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Quantitative Imaging ◽  
Cell Receptor ◽  
Germinal Centers ◽  
Affinity Maturation ◽  
Neutralizing Capacity ◽  
Large Expansion ◽  
Protective Antibodies ◽  
Human Infections

Nearly all chronic human infections are associated with alterations in the memory B cell (MBC) compartment, including a large expansion of CD19hiT-bethi MBC in the peripheral blood of HIV-infected individuals with chronic viremia. Despite their prevalence, it is unclear how these B cells arise and whether they contribute to the inefficiency of antibody-mediated immunity in chronic infectious diseases. We addressed these questions by characterizing T-bet–expressing B cells in lymph nodes (LN) and identifying a strong T-bet signature among HIV-specific MBC associated with poor immunologic outcome. Confocal microscopy and quantitative imaging revealed that T-bethi B cells in LN of HIV-infected chronically viremic individuals distinctly accumulated outside germinal centers (GC), which are critical for optimal antibody responses. In single-cell analyses, LN T-bethi B cells of HIV-infected individuals were almost exclusively found among CD19hi MBC and expressed reduced GC-homing receptors. Furthermore, HIV-specific B cells of infected individuals were enriched among LN CD19hiT-bethi MBC and displayed a distinct transcriptome, with features similar to CD19hiT-bethi MBC in blood and LN GC B cells (GCBC). LN CD19hiT-bethi MBC were also related to GCBC by B cell receptor (BCR)–based phylogenetic linkage but had lower BCR mutation frequencies and reduced HIV-neutralizing capacity, consistent with diminished participation in GC-mediated affinity selection. Thus, in the setting of chronic immune activation associated with HIV viremia, failure of HIV-specific B cells to enter or remain in GC may help explain the rarity of high-affinity protective antibodies.

scholarly journals BCR Affinity Influences T-B Interactions and B Cell Development in Secondary Lymphoid Organs

2021 ◽  
Vol 12 ◽  
Author(s):  
Alec J. Wishnie ◽  
Tzippora Chwat-Edelstein ◽  
Mary Attaway ◽  
Bao Q. Vuong
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
Affinity Maturation ◽  
B Cell Receptor ◽  
Specific Cell ◽  
High Affinity ◽  
Tfh Cells

B cells produce high-affinity immunoglobulins (Igs), or antibodies, to eliminate foreign pathogens. Mature, naïve B cells expressing an antigen-specific cell surface Ig, or B cell receptor (BCR), are directed toward either an extrafollicular (EF) or germinal center (GC) response upon antigen binding. B cell interactions with CD4+ pre-T follicular helper (pre-Tfh) cells at the T-B border and effector Tfh cells in the B cell follicle and GC control B cell development in response to antigen. Here, we review recent studies demonstrating the role of B cell receptor (BCR) affinity in modulating T-B interactions and the subsequent differentiation of B cells in the EF and GC response. Overall, these studies demonstrate that B cells expressing high affinity BCRs preferentially differentiate into antibody secreting cells (ASCs) while those expressing low affinity BCRs undergo further affinity maturation or differentiate into memory B cells (MBCs).

The immunoglobulin heavy-chain locus hs3b and hs4 3′ enhancers are dispensable for VDJ assembly and somatic hypermutation

Blood ◽  
2003 ◽  
Vol 102 (4) ◽  
pp. 1421-1427 ◽  
Author(s):  
Caroline Le Morvan ◽  
Eric Pinaud ◽  
Catherine Decourt ◽  
Armelle Cuvillier ◽  
Michel Cogné
Keyword(s):  
B Cells ◽  
B Cell ◽  
Heavy Chain ◽  
Somatic Hypermutation ◽  
Class Switch Recombination ◽  
Immunoglobulin Heavy Chain ◽  
Germinal Centers ◽  
Affinity Maturation ◽  
Class Switch ◽  
Endogenous Locus

Abstract The more distal enhancers of the immunoglobulin heavy-chain 3′ regulatory region, hs3b and hs4, were recently demonstrated as master control elements of germline transcription and class switch recombination to most immunoglobulin constant genes. In addition, they were shown to enhance the accumulation of somatic mutations on linked transgenes. Since somatic hypermutation and class switch recombination are tightly linked processes, their common dependency on the endogenous locus 3′ enhancers could be an attractive hypothesis. VDJ structure and somatic hypermutation were analyzed in B cells from mice carrying either a heterozygous or a homozygous deletion of these enhancers. We find that hs3b and hs4 are dispensable both for VDJ assembly and for the occurrence of mutations at a physiologic frequency in the endogenous locus. In addition, we show that cells functionally expressing the immunoglobulin M (IgM) class B-cell receptor encoded by an hs3b/hs4-deficient locus were fully able to enter germinal centers, undergo affinity maturation, and yield specific antibody responses in homozygous mutant mice, where IgG1 antibodies compensated for the defect in other IgG isotypes. By contrast, analysis of Peyer patches from heterozygous animals showed that peanut agglutinin (PNAhigh) B cells functionally expressing the hs3b/hs4-deficient allele were dramatically outclassed by B cells expressing the wild-type locus and normally switching to IgA. This study thus also highlights the role of germinal centers in the competition between B cells for affinity maturation and suggests that membrane IgA may promote recruitment in an activated B-cell compartment, or proliferation of activated B cells, more efficiently than IgM in Peyer patches.

scholarly journals Germinal Centers without T Cells

2000 ◽  
Vol 191 (3) ◽  
pp. 485-494 ◽  
Author(s):  
Carola García de Vinuesa ◽  
Matthew C. Cook ◽  
Jennifer Ball ◽  
Marion Drew ◽  
Yvonne Sunners ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
High Efficiency ◽  
Germinal Centers ◽  
Affinity Maturation ◽  
High Affinity ◽  
Safe Mechanism ◽  
Germinal Center Formation

Germinal centers are critical for affinity maturation of antibody (Ab) responses. This process allows the production of high-efficiency neutralizing Ab that protects against virus infection and bacterial exotoxins. In germinal centers, responding B cells selectively mutate the genes that encode their receptors for antigen. This process can change Ab affinity and specificity. The mutated cells that produce high-affinity Ab are selected to become Ab-forming or memory B cells, whereas cells that have lost affinity or acquired autoreactivity are eliminated. Normally, T cells are critical for germinal center formation and subsequent B cell selection. Both processes involve engagement of CD40 on B cells by T cells. This report describes how high-affinity B cells can be induced to form large germinal centers in response to (4-hydroxy-3-nitrophenyl) acetyl (NP)-Ficoll in the absence of T cells or signaling through CD40 or CD28. This requires extensive cross-linking of the B cell receptors, and a frequency of antigen-specific B cells of at least 1 in 1,000. These germinal centers abort dramatically at the time when mutated high-affinity B cells are normally selected by T cells. Thus, there is a fail-safe mechanism against autoreactivity, even in the event of thymus-independent germinal center formation.

scholarly journals Highly sensitive and unbiased approach for elucidating antibody repertoires

2016 ◽  
Vol 113 (28) ◽  
pp. 7846-7851 ◽  
Author(s):  
Sherry G. Lin ◽  
Zhaoqing Ba ◽  
Zhou Du ◽  
Yu Zhang ◽  
Jiazhi Hu ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Germ Line ◽  
Variable Region ◽  
Cell Receptor ◽  
Affinity Maturation ◽  
Antigen Binding ◽  
Variable Regions ◽  
Antibody Repertoires ◽  
B Lineage

Developing B lymphocytes undergo V(D)J recombination to assemble germ-line V, D, and J gene segments into exons that encode the antigen-binding variable region of Ig heavy (H) and light (L) chains. IgH and IgL chains associate to form the B-cell receptor (BCR), which, upon antigen binding, activates B cells to secrete BCR as an antibody. Each of the huge number of clonally independent B cells expresses a unique set of IgH and IgL variable regions. The ability of V(D)J recombination to generate vast primary B-cell repertoires results from a combinatorial assortment of large numbers of different V, D, and J segments, coupled with diversification of the junctions between them to generate the complementary determining region 3 (CDR3) for antigen contact. Approaches to evaluate in depth the content of primary antibody repertoires and, ultimately, to study how they are further molded by secondary mutation and affinity maturation processes are of great importance to the B-cell development, vaccine, and antibody fields. We now describe an unbiased, sensitive, and readily accessible assay, referred to as high-throughput genome-wide translocation sequencing-adapted repertoire sequencing (HTGTS-Rep-seq), to quantify antibody repertoires. HTGTS-Rep-seq quantitatively identifies the vast majority of IgH and IgL V(D)J exons, including their unique CDR3 sequences, from progenitor and mature mouse B lineage cells via the use of specific J primers. HTGTS-Rep-seq also accurately quantifies DJH intermediates and V(D)J exons in either productive or nonproductive configurations. HTGTS-Rep-seq should be useful for studies of human samples, including clonal B-cell expansions, and also for following antibody affinity maturation processes.

scholarly journals Positive Selection in the Light Zone of Germinal Centers

2021 ◽  
Vol 12 ◽  
Author(s):  
Rinako Nakagawa ◽  
Dinis Pedro Calado
Keyword(s):  
B Cells ◽  
Positive Selection ◽  
B Cell ◽  
Plasma Cells ◽  
Selection Process ◽  
Germinal Centers ◽  
Affinity Maturation ◽  
Memory B Cells ◽  
Cell Fates ◽  
High Affinity

Germinal centers (GCs) are essential sites for the production of high-affinity antibody secreting plasma cells (PCs) and memory-B cells (MBCs), which form the framework of vaccination. Affinity maturation and permissive selection in GCs are key for the production of PCs and MBCs, respectively. For these purposes, GCs positively select “fit” cells in the light zone of the GC and instructs them for one of three known B cell fates: PCs, MBCs and persistent GC-B cells as dark zone entrants. In this review, we provide an overview of the positive selection process and discuss its mechanisms and how B cell fates are instructed.

scholarly journals Memory-like B cells emerging from germinal centres recycle through the subcapsular sinus

2020 ◽  
Author(s):  
Yang Zhang ◽  
Laura Garcia-Ibanez ◽  
Carolin Ulbricht ◽  
Laurence S C Lok ◽  
Thomas W Dennison ◽  
...  
Keyword(s):  
Lymph Node ◽  
B Cells ◽  
Plasma Cells ◽  
Antigenic Variation ◽  
Cell Receptor ◽  
Germinal Centers ◽  
Affinity Maturation ◽  
Antigenic Drift ◽  
Antigen Receptors ◽  
Subcapsular Sinus

Infection or vaccination leads to the development of germinal centers (GCs) where B cells evolve high affinity antigen receptors, eventually producing antibody-forming plasma cells or memory B cells. We followed the migratory pathways of B cells emerging from germinal centers (BEM) and found that many migrated into the lymph node subcapsular sinus (SCS) guided by sphingosine-1-phosphate (S1P). From there, B cells may exit the lymph node to enter distant tissues. Some BEM cells interacted with and took up antigen from SCS macrophages, followed by CCL21-guided return towards the GC. Disruption of local CCL21 gradients inhibited the recycling of BEM cells and resulted in less efficient adaption to antigenic variation. Our findings suggest that the recycling of BEM cells, that transport antigen and that contain the genetic code for B cell receptor variants, may support affinity maturation to antigenic drift.

scholarly journals Ubiquitin-mediated fluctuations in MHC class II facilitate efficient germinal center B cell responses

2016 ◽  
Vol 213 (6) ◽  
pp. 993-1009 ◽  
Author(s):  
Oliver Bannard ◽  
Simon J. McGowan ◽  
Jonatan Ersching ◽  
Satoshi Ishido ◽  
Gabriel D. Victora ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Mhc Class Ii ◽  
Somatic Hypermutation ◽  
Ectopic Expression ◽  
Cell Receptor ◽  
Class Ii ◽  
Affinity Maturation ◽  
Efficiency Of Selection ◽  
T Cell Help

Antibody affinity maturation occurs in germinal centers (GCs) through iterative rounds of somatic hypermutation and selection. Selection involves B cells competing for T cell help based on the amount of antigen they capture and present on their MHC class II (MHCII) proteins. How GC B cells are able to rapidly and repeatedly transition between mutating their B cell receptor genes and then being selected shortly after is not known. We report that MHCII surface levels and degradation are dynamically regulated in GC B cells. Through ectopic expression of a photoconvertible MHCII-mKikGR chimeric gene, we found that individual GC B cells differed in the rates of MHCII protein turnover. Fluctuations in surface MHCII levels were dependent on ubiquitination and the E3 ligase March1. Increases in March1 expression in centroblasts correlated with decreases in surface MHCII levels, whereas CD83 expression in centrocytes helped to stabilize MHCII at that stage. Defects in MHCII ubiquitination caused GC B cells to accumulate greater amounts of a specific peptide–MHCII (pMHCII), suggesting that MHCII turnover facilitates the replacement of old complexes. We propose that pMHCII complexes are periodically targeted for degradation in centroblasts to favor the presentation of recently acquired antigens, thereby promoting the fidelity and efficiency of selection.

scholarly journals Low-level Hypermutation in T Cell–independent Germinal Centers Compared with High Mutation Rates Associated with T Cell–dependent Germinal Centers

2002 ◽  
Vol 195 (3) ◽  
pp. 383-389 ◽  
Author(s):  
Kai-Michael Toellner ◽  
William E. Jenkinson ◽  
Dale R. Taylor ◽  
Mahmood Khan ◽  
Daniel M.-Y. Sze ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
Cell Receptor ◽  
Similar Rate ◽  
Germinal Centers ◽  
Stage Of Development ◽  
V Region ◽  
T Cell Help

Exceptionally germinal center formation can be induced without T cell help by polysaccharide-based antigens, but these germinal centers involute by massive B cell apoptosis at the time centrocyte selection starts. This study investigates whether B cells in germinal centers induced by the T cell–independent antigen (4-hydroxy-3-nitrophenyl)acetyl (NP) conjugated to Ficoll undergo hypermutation in their immunoglobulin V region genes. Positive controls are provided by comparing germinal centers at the same stage of development in carrier-primed mice immunized with a T cell–dependent antigen: NP protein conjugate. False positive results from background germinal centers and false negatives from non-B cells in germinal centers were avoided by transferring B cells with a transgenic B cell receptor into congenic controls not carrying the transgene. By 4 d after immunization, hypermutation was well advanced in the T cell–dependent germinal centers. By contrast, the mutation rate for T cell–independent germinal centers was low, but significantly higher than in NP-specific B cells from nonimmunized transgenic mice. Interestingly, a similar rate of mutation was seen in extrafollicular plasma cells at this stage. It is concluded that efficient activation of hypermutation depends on interaction with T cells, but some hypermutation may be induced without such signals, even outside germinal centers.

scholarly journals Antigen recognition strength regulates the choice between extrafollicular plasma cell and germinal center B cell differentiation

2006 ◽  
Vol 203 (4) ◽  
pp. 1081-1091 ◽  
Author(s):  
Didrik Paus ◽  
Tri Giang Phan ◽  
Tyani D. Chan ◽  
Sandra Gardam ◽  
Antony Basten ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Plasma Cell ◽  
Germinal Center ◽  
Germinal Centers ◽  
Affinity Maturation ◽  
B Cell Differentiation ◽  
High Affinity ◽  
Germinal Center B Cell

B cells responding to T-dependent antigen either differentiate rapidly into extrafollicular plasma cells or enter germinal centers and undergo somatic hypermutation and affinity maturation. However, the physiological cues that direct B cell differentiation down one pathway versus the other are unknown. Here we show that the strength of the initial interaction between B cell receptor (BCR) and antigen is a primary determinant of this decision. B cells expressing a defined BCR specificity for hen egg lysozyme (HEL) were challenged with sheep red blood cell conjugates of a series of recombinant mutant HEL proteins engineered to bind this BCR over a 10,000-fold affinity range. Decreasing either initial BCR affinity or antigen density was found to selectively remove the extrafollicular plasma cell response but leave the germinal center response intact. Moreover, analysis of competing B cells revealed that high affinity specificities are more prevalent in the extrafollicular plasma cell versus the germinal center B cell response. Thus, the effectiveness of early T-dependent antibody responses is optimized by preferentially steering B cells reactive against either high affinity or abundant epitopes toward extrafollicular plasma cell differentiation. Conversely, responding clones with weaker antigen reactivity are primarily directed to germinal centers where they undergo affinity maturation.

scholarly journals Antihomotypic affinity maturation improves human B cell responses against a repetitive epitope

Science ◽  
2018 ◽  
Vol 360 (6395) ◽  
pp. 1358-1362 ◽  
Author(s):  
Katharina Imkeller ◽  
Stephen W. Scally ◽  
Alexandre Bosch ◽  
Gemma Pidelaserra Martí ◽  
Giulia Costa ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Clonal Selection ◽  
Mechanistic Explanation ◽  
Affinity Maturation ◽  
B Cell Activation ◽  
Human B Cells ◽  
Repetitive Nature ◽  
Protective Antibodies

Affinity maturation selects B cells expressing somatically mutated antibody variants with improved antigen-binding properties to protect from invading pathogens. We determined the molecular mechanism underlying the clonal selection and affinity maturation of human B cells expressing protective antibodies against the circumsporozoite protein of the malaria parasite Plasmodium falciparum (PfCSP). We show in molecular detail that the repetitive nature of PfCSP facilitates direct homotypic interactions between two PfCSP repeat-bound monoclonal antibodies, thereby improving antigen affinity and B cell activation. These data provide a mechanistic explanation for the strong selection of somatic mutations that mediate homotypic antibody interactions after repeated parasite exposure in humans. Our findings demonstrate a different mode of antigen-mediated affinity maturation to improve antibody responses to PfCSP and presumably other repetitive antigens.

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