scholarly journals “De novo Classification of Mouse B Cell Types using Surfaceome Proteotype Maps”

2019 ◽  
Author(s):  
Marc van Oostrum ◽  
Maik Müller ◽  
Fabian Klein ◽  
Roland Bruderer ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
Cell Surface ◽  
B Cell ◽  
De Novo ◽  
Cell Types ◽  
Glycosylation Sites ◽  
Cell Subpopulations

AbstractSystem-wide quantification of the cell surface proteotype and identification of extracellular glycosylation sites is challenging when sample is limiting. We miniaturized and automated the previously described Cell Surface Capture technology increasing sensitivity, reproducibility, and throughput. We used this technology, which we call autoCSC, to create population-specific surfaceome maps of developing mouse B cells and used targeted flow cytometry to uncover developmental cell subpopulations.

scholarly journals Classification of mouse B cell types using surfaceome proteotype maps

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Marc van Oostrum ◽  
Maik Müller ◽  
Fabian Klein ◽  
Roland Bruderer ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
Cell Surface ◽  
B Cell ◽  
Cell Types ◽  
Glycosylation Sites ◽  
Cell Subpopulations

AbstractSystem-wide quantification of the cell surface proteotype and identification of extracellular glycosylation sites is challenging when samples are limited. Here, we miniaturize and automate the previously described Cell Surface Capture (CSC) technology, increasing sensitivity, reproducibility and throughput. We use this technology, which we call autoCSC, to create population-specific surfaceome maps of developing mouse B cells and use targeted flow cytometry to uncover developmental cell subpopulations.

Targeting the Human Notch 2-BCR Axis: A Driver of B-Cell Hyper-Responsiveness in Active Chronic Graft-Versus Host Disease (cGVHD)

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 145-145
Author(s):  
Jonathan C. Poe ◽  
Wei Jia ◽  
Zhiguo Li ◽  
Frances T. Hakim ◽  
Steven Z. Pavletic ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
Cell Surface ◽  
B Cell ◽  
Notch Signaling ◽  
Graft Versus Host Disease ◽  
Notch Ligand ◽  
Host Disease ◽  
Graft Versus Host ◽  
B Cell Subsets

Abstract While Notch signaling is being well studied with regard to T cell pathology and graft-versus host disease (GVHD) (Tran IT et al., 2013. J. Clin. Invest.), the role of Notch receptors in the development and activation of B cell subsets in chronic GVHD (cGVHD) genesis remains unknown. We previously identified a subset of Ôpre-germinal centerÕ B cells within the peripheral blood of cGVHD patients that is largely absent in patients without cGVHD. In addition to cell surface characteristics, this extrafollicular B cell subset has potential functional characteristics of marginal zone (MZ)-like B cells, including increased responsiveness to surrogate antigen stimulation. Along with increased proliferative responses to BCR stimulation, B cells from patients with active cGVHD had significantly increased signaling via proximal B cell receptor (BCR) molecules, including Syk and BLNK. In murine models with lymphopenic environments, Notch 2 binds the ligand Delta-like 1 (DLL1/Dll1) and drives maturation of MZ-like B cells. Also, healthy human B cells have increased Notch receptor responsiveness after BCR stimulation. Together previous studies allowed us to hypothesize that a Notch 2 signaling axis underpins B cell hyper-responsiveness in human cGVHD. We found that limiting dose BCR stimulation with surrogate antigen in the presence of Notch ligand over-expressing cells (OP9-DL1) resulted in maintenance of cell surface Notch 2 expression at significantly higher levels on B cells from patients with active cGVHD compared to patients without cGVHD, as assessed by flow cytometry analysis (P < 0.01). We also found that in the presence of Notch ligand, B cells from patients with active cGVHD responded to minimal BCR stimulation with surrogate antigen. Using nearly 100x less surrogate antigen than was required to induce proliferation without Notch ligand, cGVHD B cells proliferated to a significantly greater degree than B cells from patients with no cGVHD, as evaluated by Ki-67 staining using flow cytometry (P < 0.001 in a two-sided t-test, Figure 1A). Likewise, concomitant BCR- Notch activation of active cGVHD patient B cells was associated with significantly increased B-cell size compared to patients without disease (P < 0.01). BLNK expression in active cGVHD B cells was also maintained at higher levels under these conditions, suggesting a mechanistic link between the BCR and Notch pathways in cGVHD. Strikingly, targeting Notch 2 with an antagonistic monoclonal antibody (mAb) (Wu Y et al., 2010. Nature; kindly provided by Genentech, Inc.) completely abrogated the BCR-Notch axis hyper-responsiveness of active cGVHD B cells without affecting B-cell survival (P < 0.001, Figure 1B). In this in vitro system, using nanoString Technologies¨ gene profiling, we found that two, well-defined effector genes downstream of Notch signaling were significantly decreased in active cGVHD B cells after exposure to the anti-Notch 2 mAb (P = 0.0006 and P < 0.02, respectively, compared to isotype control mAb). Also consistent with a Notch 2-driven activation pathway, the expression of multiple genes involved in homeostasis/cell cycle regulation were altered in active cGVHD B cells exposed to anti-Notch 2 mAb (P < 0.01). Finally, ongoing in vivo analyses of the Notch 2 mAb in a pre-clinical mouse model of cGVHD indicates that Notch 2 blockade does not negatively impact early B cell recovery following bone marrow transplantation. These results may reveal that therapeutic targeting of Notch 2 alone would be sufficient to quell B cell hyper-responsiveness in active cGVHD, while preserving protective humoral immunity. In summary, our data suggest a working model in which Notch-mediated aberrant B cell maturation contributes to cGVHD pathophysiology. In this model, Notch 2 stimulation along with a combination of complex B-cell selection and tolerance mechanisms afford production of pathological B cells. Given that Notch 2 is a cell surface receptor expressed by activated B cell subsets of pathological relevance, and Notch 2 blockade has been shown to be well-tolerated in pre-clinical models, our findings support an important clinical opportunity: Targeting Notch 2 on B cells in active cGVHD represents a viable future therapeutic strategy worthy of continued investigation. This work was supported by National Institutes of Health grant 5K08-HL107756, and a Translational Research Program grant from the Leukemia & Lymphoma Society. Figure 1. Figure 1. Disclosures Rizzieri: Teva: Other: ad board, Speakers Bureau; Celgene: Other: ad board, Speakers Bureau.

scholarly journals B cell differentiation and isotype switching is related to division cycle number.

1996 ◽  
Vol 184 (1) ◽  
pp. 277-281 ◽  
Author(s):  
P D Hodgkin ◽  
J H Lee ◽  
A B Lyons
Keyword(s):  
T Cells ◽  
Cell Division ◽  
B Cells ◽  
Cell Surface ◽  
B Cell ◽  
Cell Activation ◽  
De Novo ◽  
B Cell Activation ◽  
Isotype Switching ◽  
Cycle Number

The mature, resting immunoglobulin (Ig) M, IgD+ B lymphocyte can be induced by T cells to proliferate, switch isotype, and differentiate into Ig-secreting or memory cells. Furthermore, B cell activation results in the de novo expression or loss of a number of cell surface molecules that function in cell recirculation or further interaction with T cells. Here, a novel fluorescent technique reveals that T-dependent B cell activation induces cell surface changes that correlate with division cycle number. Furthermore, striking stepwise changes are often centered on a single round of cell division. Particularly marked was the consistent increase in IgG1+ B cells after the second division cycle, from an initial level of &lt; 3% IgG1+ to a plateau of approximately 40% after six cell divisions. The relationship between the percentage of IgG1+ B cells and division number was independent of time after stimulation, indicating a requirement for cell division in isotype switching. IgD expression became negative after four divisions, and a number of changes centered on the sixth division, including the loss of IgM, CD23, and B220. The techniques used here should prove useful for tracking other differentiation pathways and for future analysis of the molecular events associated with stepwise differentiation at the single cell level.

A “Universal” Lectin-Mediated Interaction Drives B-Cell Receptor Signaling In Primary Follicular Lymphoma Cells

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4291-4291
Author(s):  
Graham Packham ◽  
Serge Krysov ◽  
Vania Coelho ◽  
Peter Johnson ◽  
Freda K. Stevenson
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
Follicular Lymphoma ◽  
B Cell ◽  
Kinase Inhibitors ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Malignant Cells ◽  
Glycosylation Sites ◽  
Mannose Binding

Abstract B-cell receptor (BCR) signaling has been identified as a critical driver of B-cell malignancies and as a target for therapeutic attack. Clinical responses to novel inhibitors of BCR-associated kinases have been relatively modest in follicular lymphoma (FL) and a more detailed knowledge of BCR function in these cells is required. Surface Ig (sIg) is unusual in FL since variable regions contain N-linked glycosylation sites which are introduced by somatic mutation. These are rarely found in normal B cells, indicating strong positive selective pressure in malignant cells. Remarkably, added sugars terminate with high mannose suggesting a novel function for FL BCRs in binding to, and perhaps receiving stimulation via, microenvironmental mannose-binding lectins. In previous studies we demonstrated that candidate mannose-binding lectins, including DC-SIGN, promote intracellular calcium mobilization in primary FL cells, but not normal B cells. In this work, we characterized in more detail the response of FL cells to DC-SIGN and its inhibition by BCR-targeted kinase inhibitors. Initial studies using immunoblotting demonstrated that, like anti-Ig antibodies, DC-SIGN caused increased phosphorylation of the downstream kinases AKT and ERK in primary FL samples. DC-SIGN treatment also resulted in increased expression of the MYC oncoprotein in a subset of samples. In contrast to FL samples, DC-SIGN did not increase AKT or ERK phosphorylation in normal B cells although anti-IgM induced strong responses in these cells. Overall, responses to DC-SIGN were similar in IgM+ and IgG+ FL samples. Flow cytometry demonstrated that DC-SIGN also increased phosphorylation of proximal signaling kinases (SYK and BTK), as well as phosphorylation of PLCγ2 in FL samples, and that DC-SIGN-induced signaling occurred within the CD19+BCL2+ malignant cells. Flow cytometry also revealed intraclonal variation in responses to DC-SIGN and, like responses to anti-Ig, DC-SIGN responses were strongest in a sub-population of malignant cells with high CD20 expression. Finally, we demonstrated that tamatinib, the active form of the SYK inhibitor pro-drug fostamatinib, significantly inhibited phosphorylation of ERK and PLCγ2 induced by either anti-Ig or DC-SIGN. Overall our results are consistent with the hypothesis that N-linked glycosylation sites, introduced into BCRs by somatic mutation, are selected for in FL since they confer signaling responsiveness following binding of environmental lectins. Like canonical antigen signaling, lectin-mediated signaling via the BCR appears to be susceptible to therapeutic blockade using kinase inhibitors. However, further analysis of this novel lectin-mediated pathway may reveal novel targets for optimal therapeutic attack. Disclosures: No relevant conflicts of interest to declare.

FcμR (TOSO/FAIM3) Is An O-Glycosylated Endocytic Receptor That Shuttles IgM From the Cell Surface to the Lysosome and Whose Expression Is Regulated by TLR Signaling

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2828-2828
Author(s):  
Berengere Vire ◽  
Alexandre David ◽  
Adrian Wiestner
Keyword(s):  
B Cells ◽  
Confocal Microscopy ◽  
Cell Surface ◽  
B Cell ◽  
Endocytic Pathway ◽  
Expression Vectors ◽  
Major Band ◽  
Glycosylation Sites

Abstract Abstract 2828 TOSO/FAIM3 has recently been identified as the long sought after Fc receptor for IgM (FcμR). Previous studies have shown that FcμR is selectively overexpressed in chronic lymphocytic leukemia (CLL) cells as compared to normal B-cells or other B cell malignancies. In this study, we extend the characterization of FcμR and identify the mechanisms regulating its trafficking and expression. In CLL cells, analysis of FcμR protein expression by immunoblotting revealed one major band around 60 kDa, a series of fainter migrating species, and a band at 41 kDa corresponding to its predicted molecular weight. By contrast, normal B cells express predominantly the 60 kDa form. Inspection of FcμR sequence revealed numerous potential O-glycosylation sites in the extracellular domain and treatment with a general inhibitor of O-glycosylation, benzyl-N-acetyl- α-galactosaminide, confirmed that FcμR is indeed heavily O-glycosylated. By immunofluorescence confocal microscopy, we determined that O-glycosylation is critical for trafficking of FcμR to the cell surface as mutations in the predicted O-glycosylation sites led to intracellular retention of FcμR in HeLa cells transfected with the appropriate expression vectors. In addition, pharmacologic inhibition of O-glycosylation decreased FcμR expression on CLL cells. Next, we used biotinylated IgM and streptavidin DyLight 488 to determine the fate of IgM bound to FcμR. Addition of IgM to CLL cells prompted rapid internalization of both IgM and FcμR, reaching half maximal internalization of cell bound IgM within one minute and virtually complete internalization within 5 minutes. By contrast, a monoclonal antibody specific for FcμR was not internalized. Using immunofluorescence confocal microscopy and co-staining with transferrin and anti-LAMP-1 antiserum, we followed IgM trafficking. FcμR transported IgM through the endocytic pathway to the lysosome, where it was degraded. This last step was chloroquine but not bortezomib sensitive, confirming the role of the lysosome in FcμR degradation. Using a series of FcμR deletion mutants, we identified a proline-rich domain that is essential for cell surface expression of FcμR and a second domain, containing a YXX Φ motif, that controls internalization. Of particular interest, but so far elusive, is a possible functional role of FcμR in CLL pathogenesis. Our data suggest that a major physiologic role of FcμR may be internalization of IgM bound cargo into cells. Given the broad reactivity of IgM such cargo likely includes a variety of infectious agents as well as cellular debris that will be transported into the lysosome and thereby brought into contact with intracellular Toll-like Receptors (TLRs). To address a possible interaction between FcμR and TLRs, we investigated the effect of TLR activation on FcμR expression. There was a striking downregulation of FcμR on CLL cells in response to activation of TLR7 (using imiquimod) or TLR9 (using CpG-ODN) that involved both inhibition of transcription as well as degradation of FcμR through the lysosome. Following CpG stimulation, FcμR mRNA decreased with a half life of approximately 3 hours; that is at the same rate as after actinomycin D treatment. At 24 hours, FcμR protein was greatly reduced in response to either CpG or imiquimod, but interestingly there was less response to CpG in IGHV unmutated than in IGHV mutated CLL samples (p<0.001). In summary, FcμR is an O-glycosylated endocytic receptor that shuttles IgM from the cell surface to the lysosome. In vivo, FcμR could play a role in presenting IgM opsonized immune complexes to intracellular TLRs resulting in B-cell activation. Further studies are needed to clarify a potential contribution of FcμR to the activation of CLL cells in vivo. In addition, owing to the rapid internalization of IgM, we are pursuing FcμR as a potential pathway for the delivery of therapeutic antibody-drug conjugates into CLL cells (to be presented in a separate abstract). This work was supported by the Intramural Research Program of the National, Heart, Lung and Blood Institute. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Mannosylation of the Tumor Immunoglobulin Variable Region Informs Cell of Origin and Environmental Interactions in DLBCL Subsets

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1505-1505 ◽  
Author(s):  
Giorgia Chiodin ◽  
Joel Allen ◽  
Philip J Rock ◽  
Enrica Antonia Martino ◽  
Beatriz Valle Argos ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
B Cell ◽  
Cell Lines ◽  
Variable Region ◽  
Antigen Binding ◽  
Cell Of Origin ◽  
Glycosylation Sites ◽  
Number Of Patients ◽  
High Mannose

Diffuse large B-cell lymphomas (DLBCL) are a heterogeneous diagnostic entity of B-cell tumors whose behavior is variably influenced by genetic changes and environmental stimuli. They are usually divided into two major subgroups, the germinal center B-cell-like DLBCL (GCB-DLBCL) and the activated B-cell-like DLBCL (ABC-DLBCL), with different cells of origin and distinct clinical behavior. From a previous analysis of a small number of patients, we found that a fraction of DLBCL acquires N-glycosylation sites by somatic hypermutation of the tumor surface immunoglobulin (sIg) variable region, suggesting a connection with follicular lymphoma (FL). In FL, this leads to addition of mannosylated glycans in the antigen binding site (sIg-Mann), which allow interaction with microenvironmental lectins including dendritic cell-specific intercellular adhesion molecule 3 grabbing non-integrin (DC-SIGN). However, the distribution and the consequences of acquired N-glycosylation motifs in DLBCL was unknown. In this study, we investigated frequency, pattern and function of the mannosylated sIg in DLBCLs. DLBCL cell lines and primary samples were analyzed for the acquisition of the N-glycosylation motifs Asparagine-X-Serine/Threonine (N-x-S/T, where x ≠ Proline) in the tumor IGHV-D-J rearranged transcripts, and for binding to DC-SIGN by flow cytometry. HILIC-UPLC and crystallography were used to define structure of the glycans located in the sIg variable region. Interaction of sIg-Mann with DC-SIGN expressing cells was measured by flow cytometry and imaged by inverted fluorescence microscopy. Intracellular signaling was measured by Phosflow. Analysis of GCB-DLBCL and ABC-DLBCL cell lines and primary samples revealed that acquired N-glycosylation sites (AGS) were common in a subset of GCB-DLBCL (51%), especially in cases with a t(14;18) translocation (88%). Remarkably, the motifs were selectively acquired in the complementary-determining-regions (CDRs) of the tumor Ig (93%). In contrast, sites were infrequent in primary ABC-DLBCL (19%) and preferentially acquired in the framework regions (51% in all ABC-DLBCL cases, 88% in IGHV4-34 ABC-DLBCL). DLBCL cell lines with AGS which bound DC-SIGN had a t(14;18) translocation and were enriched with EZH2 and KMT2D mutations, while those without AGS, and unable to bind to DC-SIGN, were not. The sites acquired in the CDRs were permissive for addition of glycans terminating at high-mannose, as revealed by immunoblotting following EndoH treatment (that digests only glycans terminating at high-mannose) of the tumor sIg and by binding to soluble DC-SIGN. This was also confirmed by HILIC-UPLC and crystal structure of a sIg-Mann+ve lymphoma-derived recombinant Fab. Binding of DC-SIGN to sIg-Mann mediated an antigen-independent signal of lower levels than that mediated by anti-Ig, as measured by increased SYK phosphorylation in the tumor B cells. The sIg-Mann+ve GCB-DLBCL, but not sIg-Mann-ve DLBCL, formed clusters round DC-SIGN expressing cells. These interactions were inhibitable or disrupted by antibodies specifically targeting the DC-SIGN carbohydrate-recognition domain. Our results refine the phenotypic and functional characteristics of a GCB-DLBCL subset, in which the cell of origin has been selected to carry glycans terminating at high-mannose in the antigen-binding region. The acquisition of sites particularly in tumors harboring the t(14;18) translocation and mutations of epigenetic modifiers suggest a cell of origin common to FL, where these features occur early at transformation. Therefore, our data suggest the presence of a tumor cell ancestor with sIg glycans and genetic features common to FL and DLBCL. These results also document that those mannoses placed in the sIg variable region are functional and engage with DC-SIGN, to receive low level signals reminiscent of those protecting B cells from apoptosis. The possibility of inhibiting this antigen-independent interaction with anti-DC-SIGN antibodies in vitro suggests a potentially exploitable way for new therapeutic intervention. Disclosures Forconi: Menarini: Consultancy; Novartis: Honoraria; Janssen-Cilag: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Speakers Bureau; Roche: Honoraria; Gilead Sciences: Research Funding; Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Speakers Bureau.

scholarly journals The expansion of activated naive DNA autoreactive B cells and its association with disease activity in systemic lupus erythematosus patients

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Kittikorn Wangriatisak ◽  
Chokchai Thanadetsuntorn ◽  
Thamonwan Krittayapoositpot ◽  
Chaniya Leepiyasakulchai ◽  
Thanitta Suangtamai ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
B Cells ◽  
Disease Activity ◽  
B Cell ◽  
Lupus Erythematosus ◽  
Systemic Lupus ◽  
Autoreactive B Cells ◽  
Dsdna Antibody ◽  
Cell Subpopulations ◽  
B Cell Subsets

Abstract Background Autoreactive B cells are well recognized as key participants in the pathogenesis of systemic lupus erythematosus (SLE). However, elucidating the particular subset of B cells in producing anti-dsDNA antibodies is limited due to their B cell heterogeneity. This study aimed to identify peripheral B cell subpopulations that display autoreactivity to DNA and contribute to lupus pathogenesis. Methods Flow cytometry was used to detect total B cell subsets (n = 20) and DNA autoreactive B cells (n = 15) in SLE patients’ peripheral blood. Clinical disease activities were assessed in SLE patients using modified SLEDAI-2 K and used for correlation analyses with expanded B cell subsets and DNA autoreactive B cells. Results The increases of circulating double negative 2 (DN2) and activated naïve (aNAV) B cells were significantly observed in SLE patients. Expanded B cell subsets and DNA autoreactive B cells represented a high proportion of aNAV B cells with overexpression of CD69 and CD86. The frequencies of aNAV B cells in total B cell populations were significantly correlated with modified SLEDAI-2 K scores. Further analysis showed that expansion of aNAV DNA autoreactive B cells was more related to disease activity and serum anti-dsDNA antibody levels than to total aNAV B cells. Conclusion Our study demonstrated an expansion of aNAV B cells in SLE patients. The association between the frequency of aNAV B cells and disease activity patients suggested that these expanded B cells may play a role in SLE pathogenesis.

scholarly journals OP0186 CHANGES IN CIRCULATING B CELL LEVELS AND IMMUNOPHENOTYPE ARE ASSOCIATED WITH DEVELOPMENT OF ARTHRITIS FOLLOWING TREATMENT WITH CHECKPOINT INHIBITORS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 112.2-113
Author(s):  
M. Gatto ◽  
S. Bjursten ◽  
C. Jonell ◽  
C. Jonsson ◽  
S. Mcgrath ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
Adverse Events ◽  
B Cell ◽  
Mononuclear Cells ◽  
Checkpoint Inhibitors ◽  
Therapy Monitoring ◽  
Cell Subset ◽  
Peripheral Blood Mononuclear ◽  
Transitional B Cells

Background:Inflammatory arthritis (IA) is frequent among rheumatic side effects induced by checkpoint inhibitor (CPI) therapy for metastatic malignancies1. While T cells are likely to sustain the inflammatory process2, fewer data are available concerning the role of B cells3.Objectives:To investigate the phenotype of circulating B cells in patients who develop CPI-induced IA (CPI-IA) and to compare it with features of B cells in patients not developing immune-related adverse events (irAE) upon CPI treatment.Methods:B cell subsets at baseline (before CPI initiation) and during CPI treatment were analyzed in CPI-IA patients and in patients receiving CPI but who did not develop irAE (non-irAE). Peripheral blood mononuclear cells (PBMC) were analyzed by flow cytometry and B cells were identified as CD19+ and divided into naïve (CD27-IgD+), memory (CD27+IgD+/-), double negative (CD27-IgD-) and transitional (CD10+CD24+CD38+/hi) B cells. Levels of CD21, an activation marker on transitional B cells, were also analyzed. Non-parametric tests were used for analysis of differences between groups.Results:Six CPI-IA and 7 non-irAE patients matched for age, gender and CPI treatment were included, who had received CPI treatment due to metastatic melanoma. Flow cytometry revealed a significant increase of circulating B cells (p=0.002) (Figure 1A) and especially of transitional B cells in CPI-IA patients vs. non-irAE (median %, range: 7.8 (4.5-11.4) vs. 3.2 (1.6-4.3),p=0.007) (Figure 1B), while no remarkable changes were seen across other subsets. Transitional B cell levels significantly decreased from active to quiescent CPI-IA in all patients (p=0.008). In two CPI-IA patients for whom baseline sampling was available, the increase of transitional levels occurred early after CPI treatment and before CPI-IA onset. Levels of expression of CD21 on transitional B cells were increased in CPI-IA vs. non-irAE (p=0.01).Conclusion:Transitional B cells are expanded in CPI-IA patients and seem to increase early after start of CPI therapy. Monitoring this B cell subset might lead to closer follow-up and earlier diagnosis of CPI-IA.References:[1]Ramos-Casals M, Brahmer JR, Callahan MK, et al. Immune-related adverse events of checkpoint inhibitors. Nat Rev Dis Primers 2020;6:38[2]Murray-Brown W, Wilsdon TD, Weedon H, et al. Nivolumab-induced synovitis is characterized by florid T cell infiltration and rapid resolution with synovial biopsy-guided therapy. J Immunother Cancer 2020;8:e000281[3]Das R, Bar N, Ferreira M, et al. Early B cell changes predict autoimmunity following combination immune checkpoint blockade. J Clin Invest. 2018;128:715-2Disclosure of Interests:None declared

scholarly journals B cell depletion impairs vaccination-induced CD8+ T cell responses in a type I interferon-dependent manner

2021 ◽  
pp. annrheumdis-2021-220435
Author(s):  
Theresa Graalmann ◽  
Katharina Borst ◽  
Himanshu Manchanda ◽  
Lea Vaas ◽  
Matthias Bruhn ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Expansion ◽  
De Novo ◽  
T Cell Responses ◽  
Type I ◽  
Cell Responses ◽  
T Cell Expansion

ObjectivesThe monoclonal anti-CD20 antibody rituximab is frequently applied in the treatment of lymphoma as well as autoimmune diseases and confers efficient depletion of recirculating B cells. Correspondingly, B cell-depleted patients barely mount de novo antibody responses during infections or vaccinations. Therefore, efficient immune responses of B cell-depleted patients largely depend on protective T cell responses.MethodsCD8+ T cell expansion was studied in rituximab-treated rheumatoid arthritis (RA) patients and B cell-deficient mice on vaccination/infection with different vaccines/pathogens.ResultsRituximab-treated RA patients vaccinated with Influvac showed reduced expansion of influenza-specific CD8+ T cells when compared with healthy controls. Moreover, B cell-deficient JHT mice infected with mouse-adapted Influenza or modified vaccinia virus Ankara showed less vigorous expansion of virus-specific CD8+ T cells than wild type mice. Of note, JHT mice do not have an intrinsic impairment of CD8+ T cell expansion, since infection with vaccinia virus induced similar T cell expansion in JHT and wild type mice. Direct type I interferon receptor signalling of B cells was necessary to induce several chemokines in B cells and to support T cell help by enhancing the expression of MHC-I.ConclusionsDepending on the stimulus, B cells can modulate CD8+ T cell responses. Thus, B cell depletion causes a deficiency of de novo antibody responses and affects the efficacy of cellular response including cytotoxic T cells. The choice of the appropriate vaccine to vaccinate B cell-depleted patients has to be re-evaluated in order to efficiently induce protective CD8+ T cell responses.

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