Activation and Proliferation of B Cell Chronic Lymphocytic Leukaemia (B-CLL) Cells through Anti-CD180, Anti-CD40 and IL-4.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4775-4775
Author(s):  
Nino Porakishvili ◽  
Maria Manoussaka ◽  
Nino Kulikova ◽  
James Walton ◽  
Amit Nathwani ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Normal Control ◽  
Cell Activation ◽  
Mononuclear Cells ◽  
Leukemic Cells ◽  
B Cell Activation ◽  
Cell Cycle Protein ◽  
Cd40 Ligation ◽  
Ki 67

Abstract Introduction: We have previously shown that Toll-like receptor RP105 (CD180) is heterogeneously expressed on B-CLL cells and that the ligation of CD180 by monoclonal antibodies (mAb) on CD180+ B-CLL cells resulted in delineation of responder and non-responder B-CLL clones [1]. In this study we have examined the role of IL-4 together with CD180 and CD40 as activation signals. Methods: Blood mononuclear cells were separated from 7 responder B-CLL patients with both mutated and unmutated Ig Vh genes and 11 controls and were cultured for 72 hours in optimum concentrations of anti-CD180 (G28-8) or anti-CD40 mAb or both in presence and absence of 15 ng/ml of IL-4. CD19+ B cells were stained with mAb to the activation marker CD86 or cell cycle protein Ki-67, measured by flow cytometry and expressed as Mean Fluorescence Intensity (MFI) or % of Ki-67+ cells. Results: B-CLL cells and normal control B cells responded to CD180-ligation by activation and proliferation (Table). Higher levels of CD86 and Ki67 were detected when both anti CD40 mAb and anti CD180 mAb were added (p<0.05) compared with either alone. IL4 alone induced both activation and proliferation of control cells and this was even higher with the leukemic cells (p<0.01) confirming that IL-4 also provides a strong survival/activatory stimulus for B-CLL cells. Addition of IL-4 had no significant enhancing effect on normal B-cells stimulated with both anti-CD180 and anti-CD40, although IL-4 synergised with anti-CD40 in B cell activation (p=0.026) and with CD180 in B cell proliferation (p=0.044). Conclusion: CD180 had an additive effect with CD40 ligation in activation and proliferation of both B-CLL cells and normal control B cells. IL-4 provides a strong additional stimulus for B-CLL cells. CD86 and Ki-67 expression by CD19+ cells CD86 Ki67 B-CLL Control B-CLL control Spontaneous −IL-4 7.2±4.1 4.0±1.0 8.1±2.7 17.4±2.3 +IL-4 22.4±11.8 11.2±4.2 17.0±12.8 23.6±14.8 CD180 −IL-4 14.7±5.8 26.9±13.0 17.1±10.9 28.1±12.0 +IL-4 35.4±14.5 30.0±14.6 26.9±25.6 48.3±9.7 CD40 −IL-4 19.4±8.8 14.8±5.2 14.9±9.7 34.0±5.1 +IL-4 286±145.5 44.0±19.4 52.7±22.8 41.0±19.8 CD180+CD40 −IL-4 32.5±12.6 97.0±26.2 28.0±10.4 65.5±26.6 +IL-4 299±163.2 63.5±27.4 49.3±14.6 55.5±26.4

scholarly journals Deep Phenotyping of CD11c+ B Cells in Systemic Autoimmunity and Controls

2021 ◽  
Vol 12 ◽  
Author(s):  
Hector Rincon-Arevalo ◽  
Annika Wiedemann ◽  
Ana-Luisa Stefanski ◽  
Marie Lettau ◽  
Franziska Szelinski ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Lupus Erythematosus ◽  
Cell Activation ◽  
B Cell Activation ◽  
Membrane Expression ◽  
Ki 67 ◽  
Inflammatory Conditions ◽  
Systemic Autoimmunity ◽  
Enhanced Expression

Circulating CD11c+ B cells are a key phenomenon in certain types of autoimmunity but have also been described in the context of regular immune responses (i.e., infections, vaccination). Using mass cytometry to profile 46 different markers on individual immune cells, we systematically initially confirmed the presence of increased CD11c+ B cells in the blood of systemic lupus erythematosus (SLE) patients. Notably, significant differences in the expression of CD21, CD27, and CD38 became apparent between CD11c− and CD11c+ B cells. We observed direct correlation of the frequency of CD21−CD27− B cells and CD21−CD38− B cells with CD11c+ B cells, which were most pronounced in SLE compared to primary Sjögren's syndrome patients (pSS) and healthy donors (HD). Thus, CD11c+ B cells resided mainly within memory subsets and were enriched in CD27−IgD−, CD21−CD27−, and CD21−CD38− B cell phenotypes. CD11c+ B cells from all donor groups (SLE, pSS, and HD) showed enhanced CD69, Ki-67, CD45RO, CD45RA, and CD19 expression, whereas the membrane expression of CXCR5 and CD21 were diminished. Notably, SLE CD11c+ B cells showed enhanced expression of the checkpoint molecules CD86, PD1, PDL1, CD137, VISTA, and CTLA-4 compared to HD. The substantial increase of CD11c+ B cells with a CD21− phenotype co-expressing distinct activation and checkpoint markers, points to a quantitative increased alternate (extrafollicular) B cell activation route possibly related to abnormal immune regulation as seen under the striking inflammatory conditions of SLE which shows a characteristic PD-1/PD-L1 upregulation.

scholarly journals Monovalent engagement of the BCR activates ovalbumin-specific transnuclear B cells

2014 ◽  
Vol 211 (2) ◽  
pp. 365-379 ◽  
Author(s):  
Ana M. Avalos ◽  
Angelina M. Bilate ◽  
Martin D. Witte ◽  
Albert K. Tai ◽  
Jiang He ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Synthetic Peptides ◽  
Cell Activation ◽  
Cell Receptor ◽  
Fine Tuning ◽  
B Cell Activation ◽  
Cd40 Ligation ◽  
Peptide Antigen ◽  
Peptide Epitope

Valency requirements for B cell activation upon antigen encounter are poorly understood. OB1 transnuclear B cells express an IgG1 B cell receptor (BCR) specific for ovalbumin (OVA), the epitope of which can be mimicked using short synthetic peptides to allow antigen-specific engagement of the BCR. By altering length and valency of epitope-bearing synthetic peptides, we examined the properties of ligands required for optimal OB1 B cell activation. Monovalent engagement of the BCR with an epitope-bearing 17-mer synthetic peptide readily activated OB1 B cells. Dimers of the minimal peptide epitope oriented in an N to N configuration were more stimulatory than their C to C counterparts. Although shorter length correlated with less activation, a monomeric 8-mer peptide epitope behaved as a weak agonist that blocked responses to cell-bound peptide antigen, a blockade which could not be reversed by CD40 ligation. The 8-mer not only delivered a suboptimal signal, which blocked subsequent responses to OVA, anti-IgG, and anti-kappa, but also competed for binding with OVA. Our results show that fine-tuning of BCR-ligand recognition can lead to B cell nonresponsiveness, activation, or inhibition.

B-Cell Chronic Lymphocytic Leukemia (B-CLL) Cells Unresponsive to CD180 Ligation Fail to Respond to Anti-IgM Stimulation as Well

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3582-3582
Author(s):  
Nino Porakishvili ◽  
Peter Lydyard ◽  
Anna Bremser ◽  
Ketki Vispute ◽  
Azka Memon ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Protein Kinases ◽  
Cell Activation ◽  
Conflicts Of Interest ◽  
Lymphocytic Leukemia ◽  
Intracellular Signalling ◽  
Orphan Receptor ◽  
B Cell Activation ◽  
Ki 67

Abstract Abstract 3582 Introduction: We have demonstrated that CD180, an orphan receptor of the Toll-like receptor family, is expressed heterogeneously on B-CLL cells, mainly on those with mutated IGVH genes. We further showed that specific ligation of CD180 with mAbs induced activation and cycling of only ~50% CD180+ B-CLL clones (“R”: responders), while CD180+ B-CLL cells unresponsive to CD180 ligation (“NR”: non-responders) or CD180− B-CLL cells could not be activated through either CD40 or IL-4 suggesting anergy. Because CD180 has a short intracellular domain, it presumably, signals through pathways associated with other receptors, such as smIgM. Indeed, engagement of smIgM or CD180 induces Lyn and Syk phosphorylation. Here we compare activation, cycling and phosphorylation of intracellular protein kinases in R and NR and CD180− B-CLL clones and B lymphocytes from healthy subjects upon ligation of smIgM. Methods: B-CLL cells were analyzed for smCD180 and smIgM, and sm CD180+IgM+ B-CLL clones were categorized as R and NR by responsiveness to CD180 ligation. Leukemic clones from 15 smCD180+IgM+R, 14 smCD180+IgM+NR, 12 smCD180−IgM+ untreated B-CLL patients and 14 healthy age-matched individuals were stimulated with goat F(ab’)2 anti-human IgM pAbs for 72h, and stained with PE~anti-CD86 mAbs, or fixed, permeabilized and stained with PE~anti-Ki-67 to assess B-cell activation and cycling, respectively. In order to study early intracellular signalling events, cells were stimulated with the same antibodies for 20 min, fixed, permeabilized and stained with Alexa Fluor~rabbit/mouse antibodies to phospho-Akt, phospho-ERK, phospho-p38MAPK, and phospho-ZAP70/Syk. Unstimulated cells in medium were used as controls. Results were assessed by flow cytometry and analyzed with the Mann-Whitney U test and paired t-test where appropriate. Results: ligation of sIgM on smCD180+IgM+R B-CLL cells resulted in a significant increase in CD86+ cells (66.3±21.7% vs 18.7±12.0%, p=0.00004) and Ki-67+ cells (38.9±10.5% vs 11.1±5.9%, p=0.0001) compared to medium controls; this was not different from the increase in activation and cycling of normal B cells (not shown). In contrast, smCD180+IgM+NR B-CLL cells failed to significantly upregulate CD86 in response to anti-IgM pAbs (20.6±13.8% vs 17.6±13.7%, p=0.334) and Ki-67 (8.4±4.6% vs 5.3±1.4%, p=0.063). Interestingly, smCD180−IgM+ B-CLL cells demonstrated diminished CD86 upregulation following sIgM ligation: 36.9±21.7% vs 11.0±4.7% in medium, p=0.058 (difference with smCD180+IgM+R B-CLL, p=0.0069). Cell cycling was also decreased: 9.7±4.1% vs 5.4±3.6% in medium, p=0.015 (difference with smCD180+IgM+R, p=0.0022). The proximal stages of anti-smIgM responses were further studied by intracellular signalling of protein kinases associated with the IgM-signalling pathway. While ligation of sIgM on control B cells and smCD180+IgM+R B-CLL cells resulted in phosphorylation of all four enzymes studied, smCD180+IgM+NR cells failed to signal downstream from ZAP70/Syk following sIgM ligation (Table 1), although there was a greater heterogeneity in smCD180+IgM+R B-CLL responses, compared to normal B cells. Importantly, smIgM ligation of smCD180−IgM+ B-CLL cells did not increase phosphorylation of Erk or p38MAPK, although some such clones responded to smIgM ligation by phosphorylation of ZAP70/Syk and Akt (data not shown). Conclusions: B-CLL clones that are smCD180+IgM+ but unresponsive to CD180 ligation (~30% of all B-CLL cases) are also unresponsive (anergic) to smIgM ligation measured by intracellular signalling, cell activation and cycling. Meanwhile, smCD180−IgM+ B-CLL clones respond heterogeneously to IgM crosslinking. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Hantavirus infection-induced B cell activation elevates free light chains levels in circulation

2021 ◽  
Vol 17 (8) ◽  
pp. e1009843
Author(s):  
Jussi Hepojoki ◽  
Luz E. Cabrera ◽  
Satu Hepojoki ◽  
Carla Bellomo ◽  
Lauri Kareinen ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Mononuclear Cells ◽  
Cell Clone ◽  
Light Chains ◽  
Hantavirus Infection ◽  
Puumala Virus ◽  
B Cell Activation ◽  
Free Light Chains

In humans, orthohantaviruses can cause hemorrhagic fever with renal syndrome (HFRS) or hantavirus pulmonary syndrome (HPS). An earlier study reported that acute Andes virus HPS caused a massive and transient elevation in the number of circulating plasmablasts with specificity towards both viral and host antigens suggestive of polyclonal B cell activation. Immunoglobulins (Igs), produced by different B cell populations, comprise heavy and light chains; however, a certain amount of free light chains (FLCs) is constantly present in serum. Upregulation of FLCs, especially clonal species, associates with renal pathogenesis by fibril or deposit formations affecting the glomeruli, induction of epithelial cell disorders, or cast formation in the tubular network. We report that acute orthohantavirus infection increases the level of Ig FLCs in serum of both HFRS and HPS patients, and that the increase correlates with the severity of acute kidney injury in HFRS. The fact that the kappa to lambda FLC ratio in the sera of HFRS and HPS patients remained within the normal range suggests polyclonal B cell activation rather than proliferation of a single B cell clone. HFRS patients demonstrated increased urinary excretion of FLCs, and we found plasma cell infiltration in archival patient kidney biopsies that we speculate to contribute to the observed FLC excreta. Analysis of hospitalized HFRS patients’ peripheral blood mononuclear cells showed elevated plasmablast levels, a fraction of which stained positive for Puumala virus antigen. Furthermore, B cells isolated from healthy donors were susceptible to Puumala virus in vitro, and the virus infection induced increased production of Igs and FLCs. The findings propose that hantaviruses directly activate B cells, and that the ensuing intense production of polyclonal Igs and FLCs may contribute to acute hantavirus infection-associated pathological findings.

scholarly journals Intrathecal B-cell activation in LGI1 antibody encephalitis

2020 ◽  
Vol 7 (2) ◽  
pp. e669 ◽  
Author(s):  
Klaus Lehmann-Horn ◽  
Sarosh R. Irani ◽  
Shengzhi Wang ◽  
Arumugam Palanichamy ◽  
Sarah Jahn ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Mononuclear Cells ◽  
Cell Activity ◽  
Oligoclonal Bands ◽  
B Cell Activation ◽  
Cell Repertoire ◽  
Antibody Titers ◽  
B Cell Subsets

ObjectiveTo study intrathecal B-cell activity in leucine-rich, glioma-inactivated 1 (LGI1) antibody encephalitis. In patients with LGI1 antibodies, the lack of CSF lymphocytosis or oligoclonal bands and serum-predominant LGI1 antibodies suggests a peripherally initiated immune response. However, it is unknown whether B cells within the CNS contribute to the ongoing pathogenesis of LGI1 antibody encephalitis.MethodsPaired CSF and peripheral blood (PB) mononuclear cells were collected from 6 patients with LGI1 antibody encephalitis and 2 patients with other neurologic diseases. Deep B-cell immune repertoire sequencing was performed on immunoglobulin heavy chain transcripts from CSF B cells and sorted PB B-cell subsets. In addition, LGI1 antibody levels were determined in CSF and PB.ResultsSerum LGI1 antibody titers were on average 127-fold higher than CSF LGI1 antibody titers. Yet, deep B-cell repertoire analysis demonstrated a restricted CSF repertoire with frequent extensive clusters of clonally related B cells connected to mature PB B cells. These clusters showed intensive mutational activity of CSF B cells, providing strong evidence for an independent CNS-based antigen-driven response in patients with LGI1 antibody encephalitis but not in controls.ConclusionsOur results demonstrate that intrathecal immunoglobulin repertoire expansion is a feature of LGI1 antibody encephalitis and suggests a need for CNS-penetrant therapies.

scholarly journals Rheumatoid Factors Induce Signaling from B Cells, Leading to Epstein-Barr Virus and B-Cell Activation

2004 ◽  
Vol 78 (18) ◽  
pp. 9918-9923 ◽  
Author(s):  
Lixin Yang ◽  
Masayuki Hakoda ◽  
Kazuya Iwabuchi ◽  
Tsuyoshi Takeda ◽  
Takao Koike ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Cell Activation ◽  
Mononuclear Cells ◽  
Rheumatoid Factors ◽  
B Cell Activation ◽  
Barr Virus ◽  
Membrane Bound ◽  
Epstein Barr

ABSTRACT B-cell antigen receptor signaling is initiated upon binding of the antigen to membrane-bound immunoblobulin (Ig), and the anti-Ig antibody (Ab) mimics this signaling. In B cells latently infected with Epstein-Barr virus (EBV), the same signals induce virus activation. We examine here whether rheumatoid factors (RFs), autoantibodies directed against the Fc portion of IgG, induce EBV and B-cell activation. As a source of RFs, RF-producing lymphoblastoid cell line (LCL) clones were isolated from peripheral blood mononuclear cells (PBMC) and synovial cells from patients with rheumatoid arthritis (RA) by EBV transformation. Burkitt's lymphoma-derived Akata cells, which are highly responsive to EBV activation by anti-Ig Abs, were used for the assay of EBV activation. Akata cells expressed IgG3 as membrane-bound Ig. RFs from a synovium-derived LCL were directed to IgG3 and induced EBV activation in 16 to 18% of Akata cells, whereas RFs from another synovium-derived LCL were directed to IgG1 and did not induce EBV activation. Pretreatment of RFs with the purified Fc fragment of human IgG completely abolished EBV activation. Furthermore, B-cell activation was assessed by incorporation of [3H]thymidine. RFs from synovium-derived LCLs efficiently induced B-cell activation, and the addition of CD40 ligand had a synergistic effect. On the other hand, RFs from PBMC-derived LCLs were polyreactive, had a lower affinity to IgG, and did not induce EBV and B-cell activation. The present findings imply a possible role for RFs as EBV and B-cell activators.

STAT3 phosphorylation mediates the stimulatory effects of interferon alpha on B cell differentiation and activation in SLE

Rheumatology ◽  
2019 ◽  
Author(s):  
Aurélie De Groof ◽  
Julie Ducreux ◽  
Floor Aleva ◽  
Andrew J Long ◽  
Alina Ferster ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Mononuclear Cells ◽  
Type I ◽  
B Cell Differentiation ◽  
B Cell Activation ◽  
Loss Of Function ◽  
Stat3 Phosphorylation

Abstract Objective Type I IFNs play a well-known role in the pathogenesis of SLE, through activation of CD4 T and antigen-presenting cells. Here, we investigated the effects of IFN alpha (IFNα) on SLE B cell activation and differentiation. Methods Peripheral blood mononuclear cells (PBMCs) and purified total or naïve B cells were obtained from healthy controls and SLE patients. The effects of IFNα on B cell differentiation were studied by flow cytometry. The role of STAT3 in B cell responses to IFNα was studied using pharmacological inhibitors and PBMCs from STAT3-deficient individuals. Results Incubation of normal PBMCs with IFNα induces a B cell differentiation pattern as observed spontaneously in SLE PBMCs. IFNα displays direct stimulatory effects on purified naïve B cells from healthy individuals, as evidenced by a significant induction of cell surface CD38 and CD95 in the presence of the cytokine. In purified naïve B cells, IFNα also induces STAT3 phosphorylation. IFNα-induced naïve B cell differentiation in total PBMCs is significantly inhibited in the presence of STAT3 inhibitors, or in PBMCs from individuals with STAT3 loss of function mutations. Spontaneous levels of STAT3, but not STAT1, phosphorylation are significantly higher in total B cells from SLE patients compared with controls. Pharmacological STAT3 inhibition in SLE PBMCs inhibits naïve B cell activation and differentiation. Conclusion IFNα displays direct stimulatory effects on B cell differentiation and activation in SLE. STAT3 phosphorylation mediates the effects of IFNα stimulation in naïve B cells, an observation that opens new therapeutic perspectives in SLE.

Expression Profile and Regulation of BAFF and APRIL Receptors in Chronic Lymphocytic Leukemia,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3880-3880
Author(s):  
Gerardo Ferrer ◽  
Kate E Hodgson ◽  
Victor Ciria ◽  
Tycho Baumann ◽  
Gael Roue ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Disease Progression ◽  
Cell Activation ◽  
Receptor Expression ◽  
Leukemic Cells ◽  
Healthy Controls ◽  
Cd40 Ligation ◽  
Mutational Status ◽  
Risk Of Disease

Abstract Abstract 3880 The two TNF family proteins, B-cell activating factor [BAFF] and a proliferation-inducing ligand [APRIL], and their three receptors, transmembrane activator and CAML interactor [TACI], B-cell maturation antigen [BCMA], and BAFF receptor [BAFF-R] are critical regulators of normal B-cell development and survival. In CLL, both proteins can rescue CLL cells from apoptosis as shown in in vitro studies. We and others have previously shown that patients with CLL and other B-cell chronic lymphoproliferative disorders show abnormal BAFF and APRIL serum levels. Additionally, a few reports indicate that CLL cells can express BAFF and APRIL receptors. Nevertheless, there is no a meaningful and comparative analysis of BAFF-R, TACI and BCMA levels in CLL. We therefore quantitatively assessed BAFF-R, TACI and BCMA on B-cells from patients with CLL and healthy controls. The expression of BAFF-R, TACI and BCMA was analyzed by flow cytometry in purified peripheral blood B cells from 42 patients with CLL and 13 healthy controls. BAFF receptor was the most highly expressed receptor in both CLL and normal B cells (MFI ratios, 161.5 and 179.1, respectively). TACI was heterogeneously expressed and almost undetectable in 15 CLL and 5 normal B cells. BCMA was expressed on all CLL and normal B cells. Furthermore, the expression of TACI and BCMA was significantly higher on CLL cells than on normal B cells (p=0.034 and p<0.001, respectively). A correlation was also observed between the expression of BAFF and APRIL receptors and prognostic factors (i.e, IGHV mutational status and cytogenetics). Higher BCMA expression on leukemic cells were detected in patients with unmutated IGHV gene and high-risk genetics (17p-, 11q-, trisomy 12 or 3 or more cytogenetics abnormalities) (p=0.045 and p=0.068). Additionally, patients with higher levels of BCMA on the CLL cells also had a significantly higher risk of disease progression, with a median progression-free interval of 57 vs. 206 months (p=0.021). We further examined whether activation signals can modulate BAFF-R, TACI and BCMA expression and thereby the sensitivity of CLL cells to respond to BAFF and APRIL. In 10 CLL patients (5 mutated, 5 unmutated) and six healthy controls, receptors expression was measured at 48 hours after stimulation with F(ab')2 antihuman IgM (10 μg/ml) and CD40L (500ng/ml) plus IL-4 (20ng/ml). Cell activation and viability, as assessed by labeling of CD69 and Annexin V/TO-PRO-3, were evaluated at 48 and 72 hours after co-stimulation with either soluble BAFF (100ng/ml) or APRIL (500ng/ml). After 48h culture, an increase of all three receptors was observed in normal B-cells in response to either BCR stimulation or CD40 ligation. In CLL cells, CD40 ligation induced a significant up-regulation of TACI expression (p=0.007) and a significant reduction of BCMA expression (p=0.007). In contrast, BCR stimulation induced almost no variation in CLL receptors expression. This was accompanied by a failure of cell activation and a significant decreased viability of CLL cells (from 36% to 24% p=0.013). Of note, no differences were observed in the regulation of BAFF and APRIL receptors nor in the activation or viability on CLL cells according to the IGHV mutational status. The addition of exogenous soluble BAFF or APRIL resulted in an increase in the viability of normal B-cells at 72 hours independently of cells stimulation through BCR or CD40 ligation. The viability of CLL cells was significantly increased upon CD40 stimulation whereas in non-stimulated or BCR-stimulated CLL cells the addition of BAFF and APRIL had a modest effect on their viability. Altogether, these results indicate that BAFF and APRIL receptors are differentially expressed on CLL and normal B-cells, with TACI and BCMA being highly expressed on leukemic cells. In addition, higher BCMA expression was significantly associated with poor prognostic variables (i.e, unmutated IGHV genes, poor cytogenetics) and higher risk of disease progression. Interestingly, activatory signals including BCR and CD40 ligation influenced BAFF and APRIL receptor expression and responsiveness to either BAFF or APRIL. CD40 ligation on CLL cells induced TACI up regulation by positively impacting on the survival promoting effect of BAFF and APRIL. Collectively, these findings link positive regulatory signals of BCR and CD40 ligation with the pro-survival effect of BAFF and APRIL and their receptors on leukemic CLL cells. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Hyaluronate-CD44 Interactions Can Induce Murine B-Cell Activation

Blood ◽  
1997 ◽  
Vol 89 (8) ◽  
pp. 2901-2908 ◽  
Author(s):  
Asimah Rafi ◽  
Mitzi Nagarkatti ◽  
Prakash S. Nagarkatti
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Critical Role ◽  
Surface Glycoprotein ◽  
B Cell Differentiation ◽  
B Cell Activation ◽  
Cell Surface Glycoprotein ◽  
Immunodeficient Mice

Abstract CD44 is a widely distributed cell surface glycoprotein whose principal ligand has been identified as hyaluronic acid (HA), a major component of the extracellular matrix (ECM). Recent studies have demonstrated that activation through CD44 leads to induction of effector function in T cells and macrophages. In the current study, we investigated whether HA or monoclonal antibodies (MoAbs) against CD44 would induce a proliferative response in mouse lymphocytes. Spleen cells from normal and nude, but not severe combined immunodeficient mice, exhibited strong proliferative responsiveness to stimulation with soluble HA or anti-CD44 MoAbs. Furthermore, purified B cells, but not T cells, were found to respond to HA. HA was unable to stimulate T cells even in the presence of antigen presenting cells (APC) and was unable to act as a costimulus in the presence of mitogenic or submitogenic concentrations of anti-CD3 MoAbs. In contrast, stimulation of B cells with HA in vitro, led to B-cell differentiation as measured by production of IgM antibodies in addition to increased expression of CD44 and decreased levels of CD45R. The fact that the B cells were responding directly to HA through its binding to CD44 and not to any contaminants or endotoxins was demonstrated by the fact that F(ab)2 fragments of anti-CD44 MoAbs or soluble CD44 fusion proteins could significantly inhibit the HA-induced proliferation of B cells. Also, HA-induced proliferation of B cells was not affected by the addition of polymixin B, and B cells from lipopolysaccharide (LPS)-unresponsive C3H/HeJ strain responded strongly to stimulation with HA. Furthermore, HA, but not chondroitin-sulfate, another major component of the ECM, induced B-cell activation. It was also noted that injection of HA intraperitoneally, triggered splenic B cell proliferation in vivo. Together, the current study demonstrates that interaction between HA and CD44 can regulate murine B-cell effector functions and that such interactions may play a critical role during normal or autoimmune responsiveness of B cells.

scholarly journals AB0024 IN VITRO CHARACTERIZATION OF CENERIMOD, A POTENT AND SELECTIVE SPHINGOSINE 1-PHOSPHATE RECEPTOR 1 (S1P1) MODULATOR IN PREVENTING MIGRATION OF NON-ACTIVATED AND ACTIVATED PRIMARY HUMAN B CELLS IN THE PRESENCE OR ABSENCE OF GLUCOCORTICOIDS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 1046.1-1046
Author(s):  
L. Schlicher ◽  
P. Kulig ◽  
M. Murphy ◽  
M. Keller
Keyword(s):  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Cell Activation ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
B Cell Activation ◽  
Human B Cells ◽  
Circulating Lymphocytes

Background:Cenerimod is a potent, selective, and orally active sphingosine 1-phosphate receptor 1 (S1P1) modulator that is currently being evaluated in a Phase 2b study in patients with systemic lupus erythematosus (SLE) (NCT03742037). S1P1 receptor modulators sequester circulating lymphocytes within lymph nodes, thereby reducing pathogenic autoimmune cells (including B lymphocytes) in the blood stream and in inflamed tissues. Extensive clinical experience has become available for the nonselective S1P receptor modulator fingolimod in relapsing forms of multiple sclerosis, supporting this therapeutic concept for the treatment of autoimmune disorders.Objectives:Although the effect of S1P-receptor modulators in reducing peripheral B cells is well documented1,2, the role of the S1P1 receptor on this cell type is only incompletely understood. In this study, the mode of action of cenerimod on primary human B cells was investigated in a series of in vitro experiments, including S1P1 receptor cell surface expression and chemotaxis towards S1P. Moreover, S1P1 expression following B cell activation in vitro was studied. As glucocorticoids (GC) are frequently used in the treatment of patients with autoimmune disorders including SLE, the potential influence of GC on the mode of action of cenerimod was evaluated.Methods:Primary human B lymphocytes from healthy donors were isolated from whole blood. In one set of experiments, cells were treated with different concentrations of cenerimod to measure S1P1 receptor internalization by flow cytometry. In a second set of experiments, isolated B cells were activated using different stimuli or left untreated. Cells were then analysed for S1P1 and CD69 cell surface expression and tested in a novel real-time S1P-mediated migration assay. In addition, the effect of physiological concentrations of GCs (prednisolone and prednisone) on cenerimod activity in preventing S1P mediated migration was tested.Results:In vitro, cenerimod led to a dose-dependent internalization of the S1P1 receptor on primary human B lymphocytes. Cenerimod also blocked migration of nonactivated and activated B lymphocytes towards S1P in a concentration-dependent manner, which is in line with the retention of lymphocytes in the lymph node and the reduction of circulating lymphocytes observed in the clinical setting. Upon B cell activation, which was monitored by CD69 upregulation, a simultaneous downregulation of S1P1 expression was detected, leading to less efficient S1P-directed cell migration. Importantly, physiological concentrations of GC did not affect the inhibitory activity of cenerimod on B cell migration.Conclusion:These results show that cenerimod, by modulating S1P1, blocks B lymphocyte migration towards its natural chemoattractant S1P and demonstrate compatibility of cenerimod with GC. These results are consistent with results of comparable experiments done previously using primary human T lymphocytes.References:[1]Nakamura M et al., Mult Scler. 2014 Sep; 20(10):1371-80.[2]Strasser DS et al., RMD Open 2020;6:e001261.Disclosure of Interests:None declared

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