scholarly journals Intracellular BH3 profiling reveals shifts in anti-apoptotic dependency in B-cell maturation and activation

2017 ◽  
Author(s):  
Joanne Dai ◽  
Micah A. Luftig
Keyword(s):  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
Human Peripheral Blood ◽  
Survival Strategies ◽  
Cell Maturation ◽  
Barr Virus ◽  
B Cell Maturation ◽  
Human B Cells ◽  
Activated B Cells

AbstractApoptosis is critical to B-cell maturation, but studies of apoptotic regulation in primary human B cells is lacking. Previously, we found that infecting human B cells with Epstein-Barr virus induces two different survival strategies (Priceet al., 2017). Here, we sought to better understand the mechanisms of apoptotic regulation in normal and activated B cells. Using intracellular BH3 profiling (iBH3), we defined the Bcl2-dependency of B-cell subsets from human peripheral blood and tonsillar lymphoid tissue as well as mitogen-activated B cells. We found that naïve and memory B cells were BCL-2 dependent, while germinal center B cells were MCL-1 dependent and plasma cells were BCL-XL dependent. Proliferating B cells activated by CpG or CD40L/IL-4 became more dependent upon MCL-1 and BCL-XL. As B-cell lymphomas often rely on survival mechanisms derived from normal and activated B cells, these findings offer new insight into potential therapeutic strategies for lymphomas.

scholarly journals Frequencies of the separate human B cell subsets activatable to Ig secretion by Epstein-Barr virus and pokeweed mitogen.

1983 ◽  
Vol 157 (6) ◽  
pp. 1808-1814 ◽  
Author(s):  
O Martínez-Maza ◽  
S Britton
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Human Peripheral Blood ◽  
Pokeweed Mitogen ◽  
Barr Virus ◽  
Human B Cells ◽  
Epstein Barr ◽  
B Cell Subsets

We have developed a microculture system suitable for limiting dilution analysis of Epstein-Barr virus (EBV)- and pokeweed mitogen (PWM)-induced activation of immunoglobulin secretion by human B cells. It was found that exogenous filler cells were not required to obtain optimal EBV-induced B cell precursor frequency (PF) estimates, although filler T cells were required for optimal PWM activation. In fact, when autologous T cells were used as filler cells, a marked decrease in the EBV-induced IgM PF was noted. Treatment of the T cells with cyclosporin A partially eliminated, and irradiation of the T cells completely eliminated, this decrease. The calculated PF of B cells activated by EBV was from 1/290 to 1/3,700 for IgM, and from 1/920 to 1/3,250 for IgG secretion. PWM activated from 1/140 to 1/3,200 B cells to IgM secretion. The results of experiments in which EBV and PWM were mixed, indicated that these two polyclonal activators operated on different B cell subpopulations. Therefore, both these agents seem to activate small, discrete subpopulations of human peripheral blood B cells to Ig secretion.

scholarly journals Replacing mouse BAFF with human BAFF does not improve B-cell maturation in hematopoietic humanized mice

2017 ◽  
Vol 1 (27) ◽  
pp. 2729-2741 ◽  
Author(s):  
Julie Lang ◽  
Bicheng Zhang ◽  
Margot Kelly ◽  
Jacob N. Peterson ◽  
Jacob Barbee ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Full Length ◽  
Cell Maturation ◽  
Humanized Mice ◽  
B Cell Maturation ◽  
Human B Cells ◽  
Key Points

Key Points Expression of full-length hBAFF from cDNA in the endogenous murine locus does not improve maturation of human B cells in hu-mice. mBAFF is not limiting the maturation of human B cells in hu-mice.

B-lymphocyte-induced maturation protein1 up-regulates the expression of B-cell maturation antigen in mouse plasma cells

2010 ◽  
Vol 37 (8) ◽  
pp. 3747-3755 ◽  
Author(s):  
Shaoli Deng ◽  
Tao Yuan ◽  
Xiaoxing Cheng ◽  
Rui Jian ◽  
Jing Jiang
Keyword(s):  
B Cell ◽  
B Lymphocyte ◽  
Plasma Cells ◽  
Cell Maturation ◽  
Mouse Plasma ◽  
B Cell Maturation ◽  
B Cell Maturation Antigen

scholarly journals Rewiring of B cell receptor signaling by Epstein–Barr virus LMP2A

2020 ◽  
Vol 117 (42) ◽  
pp. 26318-26327
Author(s):  
Kamonwan Fish ◽  
Federico Comoglio ◽  
Arthur L. Shaffer ◽  
Yanlong Ji ◽  
Kuan-Ting Pan ◽  
...  
Keyword(s):  
Cell Cycle ◽  
B Cells ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Barr Virus ◽  
Human B Cells ◽  
Bcr Signaling ◽  
Epstein Barr

Epstein–Barr virus (EBV) infects human B cells and reprograms them to allow virus replication and persistence. One key viral factor in this process is latent membrane protein 2A (LMP2A), which has been described as a B cell receptor (BCR) mimic promoting malignant transformation. However, how LMP2A signaling contributes to tumorigenesis remains elusive. By comparing LMP2A and BCR signaling in primary human B cells using phosphoproteomics and transcriptome profiling, we identified molecular mechanisms through which LMP2A affects B cell biology. Consistent with the literature, we found that LMP2A mimics a subset of BCR signaling events, including tyrosine phosphorylation of the kinase SYK, the calcium initiation complex consisting of BLNK, BTK, and PLCγ2, and its downstream transcription factor NFAT. However, the majority of LMP2A-induced signaling events markedly differed from those induced by BCR stimulation. These included differential phosphorylation of kinases, phosphatases, adaptor proteins, transcription factors such as nuclear factor κB (NF-κB) and TCF3, as well as widespread changes in the transcriptional output of LMP2A-expressing B cells. LMP2A affected apoptosis and cell-cycle checkpoints by dysregulating the expression of apoptosis regulators such as BCl-xL and the tumor suppressor retinoblastoma-associated protein 1 (RB1). LMP2A cooperated with MYC and mutant cyclin D3, two oncogenic drivers of Burkitt lymphoma, to promote proliferation and survival of primary human B cells by counteracting MYC-induced apoptosis and by inhibiting RB1 function, thereby promoting cell-cycle progression. Our results indicate that LMP2A is not a pure BCR mimic but rather rewires intracellular signaling in EBV-infected B cells that optimizes cell survival and proliferation, setting the stage for oncogenic transformation.

scholarly journals Appearance of Human Plasma Cells Following Differentiation of Human B Cells in NOD/SCID Mouse Spleen

2003 ◽  
Vol 10 (2-4) ◽  
pp. 197-202 ◽  
Author(s):  
Kentaro Kikuchi ◽  
Zhe-Xiong Lian ◽  
Xiao-Song He ◽  
Aftab A. Ansari ◽  
Miyuki Ishibashi ◽  
...  
Keyword(s):  
B Cells ◽  
Plasma Cell ◽  
Mononuclear Cells ◽  
Plasma Cells ◽  
Human Peripheral Blood ◽  
Natural Killer Cell Activity ◽  
Killer Cell ◽  
Cell Activity ◽  
Scid Mice ◽  
Human B Cells

Relatively little is known for the differentiation and maturation process of human B cells to plasma cells. This is particularly important in reconstitution work involving transfer of autoantibodies. To address this issue, we transplanted human peripheral blood mononuclear cells (PBMC) directly into the spleen of irradiated NOD/SCID mice depleted of natural killer cell activity. Within 6 weeks, naïve B cells differentiated into memory B cells and, importantly, the numbers of human CD138+plasma cells in spleen increased by 100 fold after transplantation. Plasma cell numbers correlated with the detection of human IgM and IgG in serum, indicating that human B cells had differentiated into mature plasma cells in the murine spleen. In addition to CD19+plasma cells, a distinct CD19-plasma cell population was detected, suggesting that downregulation of CD19 associated with maturation of plasma cells occurred. When purified human B cells were transplanted, those findings were not observed. Our results indicate that differentiation and maturation of human B cells and plasma cells can be investigated by transplantation of human PBMC into the spleen of NOD/SCID mice. The model will be useful for studying the differentiation of human B cells and generation of plasma cells.

Evidence for B cell maturation but not trained immunity in uninfected infants exposed to hepatitis C virus

Gut ◽  
2020 ◽  
Vol 69 (12) ◽  
pp. 2203-2213 ◽  
Author(s):  
Anton Lutckii ◽  
Benedikt Strunz ◽  
Anton Zhirkov ◽  
Olga Filipovich ◽  
Elena Rukoiatkina ◽  
...  
Keyword(s):  
Immune System ◽  
B Cells ◽  
B Cell ◽  
Immune Cells ◽  
Immune Cell ◽  
Innate Immune ◽  
Cell Maturation ◽  
Innate Immune Cells ◽  
B Cell Maturation ◽  
Exposed Uninfected

ObjectivesVertical transmission of hepatitis C virus (HCV) is rare compared with other chronic viral infections, despite that newborns have an immature, and possibly more susceptible, immune system. It further remains unclear to what extent prenatal and perinatal exposure to HCV affects immune system development in neonates.DesignTo address this, we studied B cells, innate immune cells and soluble factors in a cohort of 62 children that were either unexposed, exposed uninfected or infected with HCV. Forty of these infants were followed longitudinally from birth up until 18 months of age.ResultsAs expected, evidence for B cell maturation was observed with increased age in children, whereas few age-related changes were noticed among innate immune cells. HCV-infected children had a high frequency of HCV-specific IgG-secreting B cells. Such a response was also detected in some exposed but uninfected children but not in uninfected controls. Consistent with this, both HCV-exposed uninfected and HCV-infected infants had evidence of early B cell immune maturation with an increased proportion of IgA-positive plasma cells and upregulated CD40 expression. In contrast, actual HCV viraemia, but not mere exposure, led to alterations within myeloid immune cell populations, natural killer (NK) cells and a distinct soluble factor profile with increased levels of inflammatory cytokines and chemokines.ConclusionOur data reveal that exposure to, and infection with, HCV causes disparate effects on adaptive B cells and innate immune cell such as myeloid cells and NK cells in infants.

scholarly journals Baff Binds to the Tumor Necrosis Factor Receptor–Like Molecule B Cell Maturation Antigen and Is Important for Maintaining the Peripheral B Cell Population

2000 ◽  
Vol 192 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Jeffrey S. Thompson ◽  
Pascal Schneider ◽  
Susan L. Kalled ◽  
LiChun Wang ◽  
Eric A. Lefevre ◽  
...  
Keyword(s):  
B Cells ◽  
Tumor Necrosis Factor ◽  
B Cell ◽  
Cell Population ◽  
Tumor Necrosis ◽  
Cell Maturation ◽  
Soluble Form ◽  
B Cell Maturation ◽  
Necrosis Factor ◽  
B Cell Maturation Antigen

The tumor necrosis factor (TNF) family member B cell activating factor (BAFF) binds B cells and enhances B cell receptor–triggered proliferation. We find that B cell maturation antigen (BCMA), a predicted member of the TNF receptor family expressed primarily in mature B cells, is a receptor for BAFF. Although BCMA was previously localized to the Golgi apparatus, BCMA was found to be expressed on the surface of transfected cells and tonsillar B cells. A soluble form of BCMA, which inhibited the binding of BAFF to a B cell line, induced a dramatic decrease in the number of peripheral B cells when administered in vivo. Moreover, culturing splenic cells in the presence of BAFF increased survival of a percentage of the B cells. These results are consistent with a role for BAFF in maintaining homeostasis of the B cell population.

scholarly journals TACI and BAFF-R mediate isotype switching in B cells

2005 ◽  
Vol 201 (1) ◽  
pp. 35-39 ◽  
Author(s):  
Emanuela Castigli ◽  
Stephen A. Wilson ◽  
Sumi Scott ◽  
Fatma Dedeoglu ◽  
Shengli Xu ◽  
...  
Keyword(s):  
B Cells ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Cell Maturation ◽  
Isotype Switching ◽  
B Cell Maturation ◽  
Human B Cells ◽  
Necrosis Factor ◽  
B Cell Maturation Antigen

The tumor necrosis factor family members BAFF and APRIL induce Ig isotype switching in human B cells. We analyzed the ability of BAFF and APRIL to induce isotype switching in murine B cells to IgG1, IgA, and IgE. APRIL and BAFF each engage two receptors, transmembrane activator and calcium-modulator and cytophilin ligand interactor (TACI) and B cell maturation antigen (BCMA), on B cells. In addition, BAFF engages a third receptor on B cells, BAFF-R. To determine the role of these receptors in isotype switching, we examined B cells from mice deficient in TACI, BCMA, and BAFF-R. The results obtained indicate that both TACI and BAFF-R are able to transduce signals that result in isotype switching.

Lack of Binding of Monoclonal Protein Produced by Multiple Myeloma (MM) Cells to FcγRIIb Reduces Immunoreceptor Tyrosine-Based Inhibitory Motif (ITIM) Signaling and Provides the Rationale for a Novel Therapeutic Approach to MM

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 455-455 ◽  
Author(s):  
Jennifer Li ◽  
Mingjie Li ◽  
Cathy Wang ◽  
Jessica Wang ◽  
Eric Sanchez ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
M Protein ◽  
Binding Ability ◽  
Monoclonal Protein ◽  
Human B Cells ◽  
Human Sera ◽  
Normal Human ◽  
Time Point

Abstract Abstract 455 Functional B cell and plasma cell immune responses are dependent upon an exquisitely controlled process integrating signals from activating and inhibitory receptors present on the surface of these cells. These activating and inhibitory signaling pathways regulate both the quality and quantity of immunoglobulin (Ig) production. These signaling motifs, termed immunoreceptor tyrosine-based activation motif (ITAM) and ITIM provide the basis for two opposed signaling modules that duel for control of plasma cellular activation within the immune system. The inhibitory Fc receptor FcγRIIb is expressed on plasma cells and controls their persistence in the bone marrow and their ability to produce most serum Ig. Activation of FcγRIIb leads to the phosphorylation of ITIM and recruitment of SH2-containing protein tyrosine phosphatase-1 (SHP-1) SHP-2 and the SH2-containing inositol 5-phosphatase (SHIP) in plasma cells. FcγRIIb-mediated SHIP phosphorylation results in enhanced degradation of PtdIns (3,4,5)P, which is required for B-cell antigen receptor (BCR)-induced recruitment and activation of downstream ITAM signaling molecules. The inhibitory IgG Fc receptor FcγRIIB was the first discovered and remains the best studied example of an ITIM-containing receptor. In this study, we first investigated the IgG-binding ability of 18 MM patients and 10 normal donors to FcγRIIb using flow cytometric analysis. Each serum sample was incubated with MHC1 cells that only express FcγRIIb but do not express FcγRI and FcγRIIa. After washing three times with 1 × PBS, anti-human IgG antibody conjugated with FITC was added to the cells for another 30 minutes. The results showed MM patients' serum IgG have much lower FcγRIIb-binding ability than normal human IgG (P<0.05). Immunohistochemical staining also demonstrated MM patients' sera showed obviously less binding to the FcγRIIb on MHC1 cells compared to serum samples from normal human donors. We further analyzed the FcγRIIb-SHIP signaling pathway in normal B-cells following exposure to MM and normal human sera. Fresh human B-cells were isolated using anti-CD20 antibodies with magnetic bead selection and the cells were washed in an acidic solution (pH 4) for 1 minute to remove any bound antigen from the cell surface. Raji B-cells were also acid-treated. First, these cells were exposed to MM patients' or normal human sera for 5, 15, 30, or 60 minutes to determine the maximum time point of SHIP phosphorylation. Using a standard Western blot protocol, phosphorylated SHIP and total SHIP protein expression were visualized using an enhanced chemiluminescence detection system. The maximum time point of SHIP phosphorylation was 15 minutes. The results showed that both normal human B-cells and Raji B-cells showed markedly lower SHIP phosphorylation/total SHIP following exposure to MM patient serum compared to normal human serum which is consistent with the lack of binding of human Ig to FcγRIIb. Our findings suggest that the monoclonal protein produced by MM patients has very low FcγRIIb-binding ability and is incapable of signaling through inhibitory ITIM pathway. Most importantly, FcγRIIb is expressed on plasma cells and controls their persistence in the bone marrow in addition to Ig production. Cross-linking of FcγRIIb induces apoptosis of plasma cells (Xiang Z et al Nat Immunol 8: 419-29, 2007). Thus, it is possible that this effect prevents the induction of apoptosis in MM cells. Previous studies have reported that normal Ig is capable of inducing B-cell apoptosis. Thus, it is possible that exposure of MM cells to normal immunoglobulin may be capable of inducing apoptosis of these cells and reducing their production of M-protein. We are currently evaluating the ITIM signal transduction pathway, M-protein production and apoptosis in MM and normal B-cells following exposure to normal and MM M-protein IgG. Disclosures: No relevant conflicts of interest to declare.

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