scholarly journals B cell receptor crosslinking can augment T cell help-mediated germinal center B cell selection

2018 ◽  
Author(s):  
Jackson S. Turner ◽  
Fang Ke ◽  
Irina L. Grigorova
Keyword(s):  
T Cell ◽  
B Cell ◽  
Germinal Center ◽  
Plasma Cells ◽  
Cell Receptor ◽  
Cell Selection ◽  
Antigenic Peptides ◽  
Follicular Helper ◽  
T Cell Help

AbstractSelection of germinal center (GC) B cells with B cell receptors (BCR) possessing high affinity to foreign antigen (Ag) and their differentiation into antibody-secreting long-lived plasma cells is critical for potent long-term humoral immunity. Ag-dependent engagement of GC B cell BCR triggers Ag internalization and loading of antigenic peptides on MHCII molecules for presentation to follicular helper T cells (Tfh) and acquisition of T cell help. However, whether it also provides signals that are critical or synergistic with T cell help for GC B cell selection and differentiation in vivo is not known. Here we show that T cell help is sufficient to induce GC B cell expansion and plasmablast (PB) formation in the absence of recurrent BCR engagement with Ag. Ag-mediated BCR crosslinking on the other hand is not sufficient to promote GC B cell selection, but can synergize with T cell help to enhance the GC B cell and PB responses when T cell help is limiting.

scholarly journals B Cell Receptor Crosslinking Augments Germinal Center B Cell Selection when T Cell Help Is Limiting

Cell Reports ◽  
2018 ◽  
Vol 25 (6) ◽  
pp. 1395-1403.e4 ◽  
Author(s):  
Jackson Steed Turner ◽  
Fang Ke ◽  
Irina Leonidovna Grigorova
Keyword(s):  
T Cell ◽  
B Cell ◽  
Germinal Center ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Cell Selection ◽  
Germinal Center B Cell ◽  
T Cell Help

scholarly journals Regulation of B cell fate by chronic activity of the IgE B cell receptor

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Zhiyong Yang ◽  
Marcus J Robinson ◽  
Xiangjun Chen ◽  
Geoffrey A Smith ◽  
Jack Taunton ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Plasma Cells ◽  
Cell Receptor ◽  
Culture Conditions ◽  
B Cell Receptor ◽  
Cell Cycles ◽  
T Cell Help

IgE can trigger potent allergic responses, yet the mechanisms regulating IgE production are poorly understood. Here we reveal that IgE+ B cells are constrained by chronic activity of the IgE B cell receptor (BCR). In the absence of cognate antigen, the IgE BCR promoted terminal differentiation of B cells into plasma cells (PCs) under cell culture conditions mimicking T cell help. This antigen-independent PC differentiation involved multiple IgE domains and Syk, CD19, BLNK, Btk, and IRF4. Disruption of BCR signaling in mice led to consistently exaggerated IgE+ germinal center (GC) B cell but variably increased PC responses. We were unable to confirm reports that the IgE BCR directly promoted intrinsic apoptosis. Instead, IgE+ GC B cells exhibited poor antigen presentation and prolonged cell cycles, suggesting reduced competition for T cell help. We propose that chronic BCR activity and access to T cell help play critical roles in regulating IgE responses.

scholarly journals Rapid Emergence of T Follicular Helper and Germinal Center B Cells Following Antiretroviral Therapy in Advanced HIV Disease

2021 ◽  
Vol 12 ◽  
Author(s):  
Chun-Shu Wong ◽  
Clarisa M. Buckner ◽  
Silvia Lucena Lage ◽  
Luxin Pei ◽  
Felipe L. Assis ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
Antiretroviral Therapy ◽  
B Cell ◽  
Germinal Center ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Cd4 T Cell ◽  
Follicular Helper ◽  
Cell Counts

Low nadir CD4 T-cell counts in HIV+ patients are associated with high morbidity and mortality and lasting immune dysfunction, even after antiretroviral therapy (ART). The early events of immune recovery of T cells and B cells in severely lymphopenic HIV+ patients have not been fully characterized. In a cohort of lymphopenic (CD4 T-cell count < 100/µL) HIV+ patients, we studied mononuclear cells isolated from peripheral blood (PB) and lymph nodes (LN) pre-ART (n = 40) and 6-8 weeks post-ART (n = 30) with evaluation of cellular immunophenotypes; histology on LN sections; functionality of circulating T follicular helper (cTfh) cells; transcriptional and B-cell receptor profile on unfractionated LN and PB samples; and plasma biomarker measurements. A group of 19 healthy controls (HC, n = 19) was used as a comparator. T-cell and B-cell lymphopenia was present in PB pre-ART in HIV+ patients. CD4:CD8 and CD4 T- and B-cell PB subsets partly normalized compared to HC post-ART as viral load decreased. Strikingly in LN, ART led to a rapid decrease in interferon signaling pathways and an increase in Tfh, germinal center and IgD-CD27- B cells, consistent with histological findings of post-ART follicular hyperplasia. However, there was evidence of cTfh cells with decreased helper capacity and of limited B-cell receptor diversification post-ART. In conclusion, we found early signs of immune reconstitution, evidenced by a surge in LN germinal center cells, albeit limited in functionality, in HIV+ patients who initiate ART late in disease.

scholarly journals Follicular Helper NKT Cells Induce Limited B Cell Responses and Germinal Center Formation in the Absence of CD4+ T Cell Help

2012 ◽  
Vol 188 (7) ◽  
pp. 3217-3222 ◽  
Author(s):  
Elena Tonti ◽  
Maya Fedeli ◽  
Anna Napolitano ◽  
Matteo Iannacone ◽  
Ulrich H. von Andrian ◽  
...  
Keyword(s):  
T Cell ◽  
B Cell ◽  
Germinal Center ◽  
Nkt Cells ◽  
Cd4 T Cell ◽  
Cell Responses ◽  
Follicular Helper ◽  
Cd4 T Cell Help ◽  
T Cell Help ◽  
Germinal Center Formation

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 Long-Lasting T Cell-Independent IgG Responses Require MyD88-Mediated Pathways and Are Maintained by High Levels of Virus Persistence

mBio ◽  
2013 ◽  
Vol 4 (6) ◽  
Author(s):  
Forum M. Raval ◽  
Rabinarayan Mishra ◽  
Robert L. Garcea ◽  
Raymond M. Welsh ◽  
Eva Szomolanyi-Tsuda
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
Cell Receptor ◽  
Cell Responses ◽  
Serum Igg ◽  
B Cell Memory ◽  
T Cell Help ◽  
Serum Igg Levels

ABSTRACTMany viruses induce acute T cell-independent (TI) B cell responses due to their repetitive epitopes and the induction of innate cytokines. Nevertheless, T cell help is thought necessary for the development of long-lasting antiviral antibody responses in the form of long-lived plasma cells and memory B cells. We found that T cell-deficient (T cell receptor β and δ chain [TCRβδ] knockout [KO]) mice persistently infected with polyomavirus (PyV) had long-lasting antiviral serum IgG, and we questioned whether they could generate TI B cell memory. TCRβδ KO mice did not form germinal centers after PyV infection, lacked long-lived IgG-secreting plasma cells in bone marrow, and did not have detectable memory B cell responses. Mice deficient in CD4+T cells had a lower persisting virus load than TCRβδ KO mice, and these mice had short-lived antiviral IgG responses, suggesting that a high virus load is required to activate naive B cells continuously, and maintain the long-lasting serum IgG levels. Developing B cells in bone marrow encounter high levels of viral antigens, which can cross-link both their B cell receptor (BCR) and Toll-like receptors (TLRs), and this dual engagement may lead to a loss of their tolerance. Consistent with this hypothesis, antiviral serum IgG levels were greatly diminished in TCRβδ KO/MyD88−/−mice. We conclude that high persisting antigen levels and innate signaling can lead to the maintenance of long-lasting IgG responses even in the absence of T cell help.IMPORTANCELifelong control of persistent virus infections is essential for host survival. Several members of the polyomavirus family are prevalent in humans, persisting at low levels in most people without clinical manifestations, but causing rare morbidity/mortality in the severely immune compromised. Studying the multiple mechanisms that control viral persistence in a mouse model, we previously found that murine polyomavirus (PyV) induces protective T cell-independent (TI) antiviral IgG. TI antibody (Ab) responses are usually short-lived, but T cell-deficient PyV-infected mice can live for many months. This study investigates how protective IgG is maintained under these circumstances and shows that these mice lack both forms of B cell memory, but they still have sustained antiviral IgG responses if they have high levels of persisting virus and intact MyD88-mediated pathways. These requirements may ensure life-saving protection against pathogens even in the absence of T cells, but they prevent the continuous generation of TI IgG against harmless antigens.

scholarly journals IL-27 supports germinal center function by enhancing IL-21 production and the function of T follicular helper cells

2010 ◽  
Vol 207 (13) ◽  
pp. 2895-2906 ◽  
Author(s):  
Marcel Batten ◽  
Nandhini Ramamoorthi ◽  
Noelyn M. Kljavin ◽  
Cindy S. Ma ◽  
Jennifer H. Cox ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Germinal Center ◽  
Dependent Manner ◽  
High Affinity ◽  
Tfh Cells ◽  
Follicular Helper ◽  
Cell Clones

Maturation and selection of high-affinity B cell clones in the germinal center (GC) relies on support from T follicular helper (TFH) cells. TFH cells are characterized by their localization to the B cell follicle and their high expression of the costimulatory molecules ICOS and PD1 and the cytokine IL-21, which promotes immunoglobulin (Ig) class switching and production by B cells. We show that the heterodimeric cytokine IL-27 is critical for the function of TFH cells and for normal and pathogenic GC responses. IL-27 signaling to T cells results in the production of IL-21, a known autocrine factor for the maintenance of TFH cells, in a STAT3-dependent manner. IL-27 also enhances the survival of activated CD4+ T cells and the expression of TFH cell phenotypic markers. In vivo, expression of the IL-27Rα chain is required to support IL-21 production and TFH cell survival in a T cell–intrinsic manner. The production of high-affinity antibodies is reduced, and pristane-elicited autoantibodies and glomerulonephritis are significantly diminished, in Il27ra−/− mice. Together, our data show a nonredundant role for IL-27 in the development of T cell–dependent antibody responses.

scholarly journals Deficiency in TNFRSF13B (TACI) expands T-follicular helper and germinal center B cells via increased ICOS-ligand expression but impairs plasma cell survival

2012 ◽  
Vol 109 (38) ◽  
pp. 15401-15406 ◽  
Author(s):  
Xijun Ou ◽  
Shengli Xu ◽  
Kong-Peng Lam
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Plasma Cells ◽  
Antibody Responses ◽  
Cell Compartments ◽  
Follicular Helper ◽  
Inducible Costimulator ◽  
Ligand Expression

Mutations in TNFRSF13B, better known as transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI), contribute to common variable immunodeficiency and autoimmunity in humans. How TACI regulates these two opposing conditions is unclear, however. TACI binds the cytokines BAFF and APRIL, and previous studies using gene KO mice indicated that loss of TACI affected only T-cell–independent antibody responses. Here we demonstrate that Taci−/− mice have expanded populations of T follicular helper (Tfh) and germinal center (GC) B cells in their spleens when immunized with T-cell–dependent antigen. The increased numbers of Tfh and GC B cells in Taci−/− mice are largely a result of up-regulation of inducible costimulator (ICOS) ligand on TACI-deficient B cells, given that ablation of one copy of the Icosl allele restores normal levels of Tfh and GC B cells in Taci−/− mice. Interestingly, despite the presence of increased Tfh and antigen-specific B cells, immunized Taci−/− mice demonstrate defective antigen-specific antibody responses resulting from significantly reduced numbers of antibody-secreting cells (ASCs). This effect is attributed to the failure to down-regulate the proapoptotic molecule BIM in Taci−/− plasma cells. Ablation of BIM could rescue ASC formation in Taci−/− mice, suggesting that TACI is more important for the survival of plasma cells than for the differentiation of these cells. Thus, our data reveal dual roles for TACI in B-cell terminal differentiation. On one hand, TACI modulates ICOS ligand expression and thereby limits the size of Tfh and GC B-cell compartments and prevents autoimmunity. On the other hand, it regulates the survival of ASCs and plays an important role in humoral immunity.

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