scholarly journals B cell antigen extraction is regulated by physical properties of antigen-presenting cells

2016 ◽  
Vol 216 (1) ◽  
pp. 217-230 ◽  
Author(s):  
Katelyn M. Spillane ◽  
Pavel Tolar
Keyword(s):  
Dendritic Cells ◽  
Physical Properties ◽  
B Cell ◽  
Affinity Maturation ◽  
Artificial Substrates ◽  
Live Cells ◽  
Mechanical Forces ◽  
Immune Synapses ◽  
Pulling Forces ◽  
Antigen Presenting

Antibody production and affinity maturation are driven by B cell extraction and internalization of antigen from immune synapses. However, the extraction mechanism remains poorly understood. Here we develop DNA-based nanosensors to interrogate two previously proposed mechanisms, enzymatic liberation and mechanical force. Using antigens presented by either artificial substrates or live cells, we show that B cells primarily use force-dependent extraction and resort to enzymatic liberation only if mechanical forces fail to retrieve antigen. The use of mechanical forces renders antigen extraction sensitive to the physical properties of the presenting cells. We show that follicular dendritic cells are stiff cells that promote strong B cell pulling forces and stringent affinity discrimination. In contrast, dendritic cells are soft and promote acquisition of low-affinity antigens through low forces. Thus, the mechanical properties of B cell synapses regulate antigen extraction, suggesting that distinct properties of presenting cells support different stages of B cell responses.

scholarly journals CD40 in Clinical Inflammation: From Multiple Sclerosis to Atherosclerosis

1998 ◽  
Vol 6 (3-4) ◽  
pp. 215-222 ◽  
Author(s):  
Jon D. Laman ◽  
Mark De Boer ◽  
Bert A. 'T Hart
Keyword(s):  
Multiple Sclerosis ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cell ◽  
Antibody Production ◽  
Memory Formation ◽  
Isotype Switching ◽  
Cell Responses ◽  
Clinical Conditions ◽  
Antigen Presenting

The interactions of CD40 and CD40L have been known for some time to critically regulate B-cell responses with respect to proliferation, isotype switching, antibody production, and memory formation. More recent findings demonstrated that CD40 can be expressed on several other antigen-presenting cell (APC) types such as macrophages, dendritic cells, and fibroblasts. This expression of CD40 regulates T-cell-APC interaction and is centrally involved in a wide array of inflammatory events. Here, currently available data are reviewed demonstrating that CD40- CD40L interactions are operational in two chronic inflammatory clinical conditions, namely, multiple sclerosis and atherosclerosis. The functional correlates of these interactions are discussed in the light of recent other findings, shedding light on the multiple effects of CD40- CD40L interactions.

scholarly journals Follicular dendritic cells help resting B cells to become effective antigen-presenting cells: induction of B7/BB1 and upregulation of major histocompatibility complex class II molecules.

1993 ◽  
Vol 178 (6) ◽  
pp. 2055-2066 ◽  
Author(s):  
M H Kosco-Vilbois ◽  
D Gray ◽  
D Scheidegger ◽  
M Julius
Keyword(s):  
Dendritic Cells ◽  
Major Histocompatibility Complex ◽  
B Cells ◽  
Major Histocompatibility Complex Class ◽  
B Cell ◽  
Antigen Presenting Cells ◽  
Follicular Dendritic Cells ◽  
Complex Class ◽  
Histocompatibility Complex ◽  
Antigen Presenting

This study was designed to investigate whether follicular dendritic cells (FDC) can activate B cells to a state in which they can function as effective antigen-presenting cells (APC). High buoyant density (i.e., resting) B cells specific for 2,4-dinitro-fluorobenzene (DNP) were incubated with DNP-ovalbumin (OVA) bearing FDC, after which their capacity to process and present to an OVA-specific T cell clone was assessed. The efficacies of alternative sources of antigen and activation signals in the induction of B cell APC function were compared with those provided by FDC. Only FDC and Sepharose beads coated with anti-immunoglobulin (Ig)kappa monoclonal antibody provided the necessary stimulus. FDC carrying inappropriate antigens also induced B cell APC function in the presence of exogenous DNP-OVA. However, in circumstances where soluble DNP-OVA was limiting, FDC bearing complexes containing DNP, which could crosslink B cell Ig receptors, induced the most potent APC function. Analysis by flow cytometry revealed that within 24 h of coculture with FDC, a significant percentage of B cells increased in size and expressed higher levels of major histocompatibility complex class II. By 48 h, an upregulation of the costimulatory molecule, B7/BB1, occurred, but only when exposed to the FDC bearing DNP. Taken together, the results demonstrate that FDC have the capacity to activate resting B cells to a state in which they can function as APC for T cells. The stimuli that FDC provide may include: (a) an antigen-dependent signal that influences the upregulation of B7/BB1; and (b) possibly a signal independent of crosslinking mIg that results in Ig internalization. The relevance of these findings to the formation of germinal centers and maintenance of the humoral response is discussed.

scholarly journals IL-6 Production by Dendritic Cells Is Dispensable for CD8+Memory T-Cell Generation

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Jean-François Daudelin ◽  
Mélissa Mathieu ◽  
Salix Boulet ◽  
Nathalie Labrecque
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cell ◽  
Memory T Cells ◽  
T Cell Memory ◽  
Memory Cells ◽  
Differential Outcome ◽  
Memory T Cell ◽  
Antigen Presenting

Following activation, naïve CD8+T cells will differentiate into effectors that differ in their ability to survive: some will persist as memory cells while the majority will die by apoptosis. Signals given by antigen-presenting cells (APCs) at the time of priming modulate this differential outcome. We have recently shown that, in opposition to dendritic cell (DC), CD40-activated B-(CD40-B) cell vaccination fails to efficiently produce CD8+memory T cells. Understanding why CD40-B-cell vaccination does not lead to the generation of functional long-lived memory cells is essential to define the signals that should be provided to naïve T cells by APCs. Here we show that CD40-B cells produce very low amount of IL-6 when compared to DCs. However, supplementation with IL-6 during CD40-B-cell vaccination did not improve memory generation. Furthermore, IL-6-deficient DCs maintained the capacity to promote the formation of functional CD8+effectors and memory cells. Our results suggest that in APC vaccination models, IL-6 provided by the APCs is dispensable for proper CD8+T-cell memory generation.

scholarly journals T Cell Accumulation in B Cell Follicles Is Regulated by Dendritic Cells and Is Independent of B Cell Activation

2003 ◽  
Vol 197 (2) ◽  
pp. 195-206 ◽  
Author(s):  
Simon Fillatreau ◽  
David Gray
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
B Cell Activation ◽  
Cell Accumulation ◽  
Antigen Presenting ◽  
Deficient Mice

We investigated the mechanism of CD4 T cell accumulation in B cell follicles after immunization. Follicular T cell numbers were correlated with the number of B cells, indicating B cell control of the niche that T cells occupy. Despite this, we found no role for B cells in the follicular migration of T cells. Instead, T cells are induced to migrate into B cell follicles entirely as a result of interaction with dendritic cells (DCs). Migration relies on CD40-dependent maturation of DCs, as it did not occur in CD40-deficient mice but was reconstituted with CD40+ DCs. Restoration was not achieved by the activation of DCs with bacterial activators (e.g., lipopolysaccharide, CpG), but was by the injection of OX40L–huIgG1 fusion protein. Crucially, the up-regulation of OX40L (on antigen-presenting cells) and CXCR-5 (on T cells) are CD40-dependent events and we show that T cells do not migrate to follicles in immunized OX40-deficient mice.

scholarly journals Visualizing B cell capture of cognate antigen from follicular dendritic cells

2009 ◽  
Vol 206 (7) ◽  
pp. 1485-1493 ◽  
Author(s):  
Kazuhiro Suzuki ◽  
Irina Grigorova ◽  
Tri Giang Phan ◽  
Lisa M. Kelly ◽  
Jason G. Cyster
Keyword(s):  
Dendritic Cells ◽  
B Cells ◽  
B Cell ◽  
Information Transfer ◽  
Surface Proteins ◽  
Follicular Dendritic Cells ◽  
Cell Capture ◽  
Cognate Antigen ◽  
Follicular Dendritic ◽  
Antigen Presenting

The prominent display of opsonized antigen by follicular dendritic cells (FDCs) has long favored the view that they serve as antigen-presenting cells for B cells. Surprisingly, however, although B cell capture of antigen from macrophages and dendritic cells has been visualized, acquisition from FDCs has not been directly observed. Using two-photon microscopy, we visualized B cell capture of cognate antigen from FDCs. B cell CXCR5 expression was required, and encounter with FDC-associated antigen could be detected for >1 wk after immunization. B cell–FDC contact times were often brief but occasionally persisted for >30 min, and B cells sometimes acquired antigen together with FDC surface proteins. These observations establish that FDCs can serve as sites of B cell antigen capture, with their prolonged display time ensuring that even rare B cells have the chance of antigen encounter, and they suggest possible information transfer from antigen-presenting cell to B cell.

scholarly journals Excessive CD11c+Tbet+B cells promote aberrant TFHdifferentiation and affinity-based germinal center selection in lupus

2019 ◽  
Vol 116 (37) ◽  
pp. 18550-18560 ◽  
Author(s):  
Wenqian Zhang ◽  
Huihui Zhang ◽  
Shujun Liu ◽  
Fucan Xia ◽  
Zijian Kang ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Molecular Mechanisms ◽  
Affinity Maturation ◽  
Antibody Affinity ◽  
Autoantibody Production ◽  
Cell Responses ◽  
Antigen Presenting

Excessive self-reactive and inadequate affinity-matured antigen-specific antibody responses have been reported to coexist in lupus, with elusive cellular and molecular mechanisms. Here, we report that the antigen-specific germinal center (GC) response―a process critical for antibody affinity maturation―is compromised in murine lupus models. Importantly, this defect can be triggered by excessive autoimmunity-relevant CD11c+Tbet+age-associated B cells (ABCs). In B cell-intrinsic Ship-deficient (ShipΔB) lupus mice, excessive CD11c+Tbet+ABCs induce deregulated follicular T-helper (TFH) cell differentiation through their potent antigen-presenting function and consequently compromise affinity-based GC selection. Excessive CD11c+Tbet+ABCs and deregulated TFHcell are also present in other lupus models and patients. Further, over-activated Toll-like receptor signaling in Ship-deficient B cells is critical for CD11c+Tbet+ABC differentiation, and blocking CD11c+Tbet+ABC differentiation in ShipΔB mice by ablating MyD88 normalizes TFHcell differentiation and rescues antigen-specific GC responses, as well as prevents autoantibody production. Our study suggests that excessive CD11c+Tbet+ABCs not only contribute significantly to autoantibody production but also compromise antigen-specific GC B-cell responses and antibody-affinity maturation, providing a cellular link between the coexisting autoantibodies and inadequate affinity-matured antigen-specific antibodies in lupus models and a potential target for treating lupus.

scholarly journals Human CD14hi monocytes and myeloid dendritic cells provide a cell contact–dependent costimulatory signal for early CD40 ligand expression

Blood ◽  
2011 ◽  
Vol 117 (5) ◽  
pp. 1585-1594 ◽  
Author(s):  
Sagarika Chakrabarty ◽  
James T. Snyder ◽  
Jijia Shen ◽  
Hooman Azmi ◽  
Paul Q. Hu ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Myeloid Dendritic Cells ◽  
A Cell ◽  
Cd40l Expression ◽  
Antigen Presenting

Abstract CD40L on CD4+ T cells plays a vital role in the activation of antigen-presenting cells, thus catalyzing a positive feedback loop for T-cell activation. Despite the pivotal juxtaposition of CD40L between antigen-presenting cells and T-cell activation, only a T-cell receptor stimulus is thought to be required for early CD40L surface expression. We show, for the first time, that CD40L expression on peripheral blood CD4+ T cells is highly dependent on a cell-cell interaction with CD14hiCD16− monocytes. Interactions with ICAM-1, LFA-3, and to a lesser extent CD80/CD86 contribute to this enhancement of CD40L expression but are not themselves sufficient. The contact-mediated increase in CD40L expression is dependent on new mRNA and protein synthesis. Circulating myeloid dendritic cells also possess this costimulatory activity. By contrast, CD14loCD16+ monocytes, plasmacytoid dendritic cells, B-cell lymphoma lines, and resting, activated, and Epstein-Barr virus–immortalized primary B cells all lack the capacity to up-regulate early CD40L. The latter indicates that a human B cell cannot activate its cognate T cell to deliver CD40L-mediated help. This finding has functional implications for the role of biphasic CD40L expression, suggesting that the early phase is associated with antigen-presenting cell activation, whereas the late phase is related to B-cell activation.

scholarly journals B cells extract antigens at Arp2/3-generated actin foci interspersed with linear filaments

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Sophie I Roper ◽  
Laabiah Wasim ◽  
Dessislava Malinova ◽  
Michael Way ◽  
Susan Cox ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Actin Polymerization ◽  
Mechanical Activity ◽  
Cytoskeleton Organization ◽  
Cell Internalization ◽  
Primary Mouse ◽  
Immune Synapses ◽  
Antigen Presenting ◽  
Cell Synapse

Antibody production depends on B cell internalization and presentation of antigens to helper T cells. To acquire antigens displayed by antigen-presenting cells, B cells form immune synapses and extract antigens by the mechanical activity of the acto-myosin cytoskeleton. While cytoskeleton organization driving the initial formation of the B cell synapse has been studied, how the cytoskeleton supports antigen extraction remains poorly understood. Here we show that after initial cell spreading, F-actin in synapses of primary mouse B cells and human B cell lines forms a highly dynamic pattern composed of actin foci interspersed with linear filaments and myosin IIa. The foci are generated by Arp2/3-mediated branched-actin polymerization and stochastically associate with antigen clusters to mediate internalization. However, antigen extraction also requires the activity of formins, which reside near the foci and produce the interspersed filaments. Thus, a cooperation of branched-actin foci supported by linear filaments underlies B cell mechanics during antigen extraction.

scholarly journals B cells extract antigens using Arp2/3-generated actin foci interspersed with linear filaments

2019 ◽  
Author(s):  
Sophie I. Roper ◽  
Laabiah Wasim ◽  
Dessislava Malinova ◽  
Michael Way ◽  
Susan Cox ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Mechanics ◽  
Actin Polymerization ◽  
Mechanical Activity ◽  
Cytoskeleton Organization ◽  
Cell Internalization ◽  
Immune Synapses ◽  
Antigen Presenting ◽  
Cell Synapse

AbstractAntibody production depends on B cell internalization and presentation of antigens to helper T cells. To acquire antigens displayed by antigen-presenting cells, B cells form immune synapses and extract antigens by the mechanical activity of the acto-myosin cytoskeleton. While cytoskeleton organization driving the initial formation of the B cell synapse has been studied, how the cytoskeleton supports antigen extraction remains poorly understood. Here we show that after initial cell spreading, F-actin in B cell synapses forms a highly dynamic pattern composed of actin foci interspersed with linear filaments and myosin IIa. The foci are generated by Arp2/3-mediated branched-actin polymerization and stochastically associate with antigen clusters to mediate internalization. However, antigen extraction also requires the activity of formins, which reside near the foci and produce the interspersed filaments. Thus, a cooperation of branched-actin foci supported by linear filaments underlies B cell mechanics during antigen extraction.

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