Presence of Membrane Platelet-activating Factor Receptors on B Cells of Chronic B Cell Leukaemia Patients

2003 ◽  
Vol 44 (6) ◽  
pp. 1087-1088 ◽  
Author(s):  
L. Guglielmi ◽  
F. Trimoreau ◽  
M. Donnard ◽  
A. Jaccard ◽  
D. Bordessoule ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Platelet Activating Factor ◽  
Cell Leukaemia

scholarly journals Anti-CD19 monoclonal antibodies for the treatment of relapsed or refractory B-cell malignancies: a narrative review with focus on diffuse large B-cell lymphoma

2021 ◽  
Author(s):  
Pier Luigi Zinzani ◽  
Giorgio Minotti
Keyword(s):  
Monoclonal Antibodies ◽  
B Cells ◽  
B Cell ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Cell Leukaemia ◽  
Antibody Drug Conjugate ◽  
B Cell Malignancies ◽  
Large B Cell Lymphoma ◽  
Large B Cell

Abstract Purpose CD19 is a cell surface protein that is found on both healthy and malignant B cells. Accordingly, it has become an important target for novel treatments for non-Hodgkin lymphomas and B-cell leukaemia. Three anti-CD19 monoclonal antibodies with distinct mechanisms of action have been developed for the treatment of B-cell malignancies. Methods We reviewed the preclinical and clinical data on the development of the newly approved anti-CD19 monoclonal antibodies blinatumomab, tafasitamab and loncastuximab tesirine, and consider their place in the treatment of relapsed or refractory B-cell malignancies. Results Blinatumomab is a bispecific T-cell engager that binds to both CD19 on B cells and CD3 on T cells, facilitating antibody-dependent cytotoxicity. Blinatumomab significantly prolongs overall survival in patients with relapsed or refractory B-cell acute lymphoblastic leukaemia, although cytokine release syndrome and severe neurotoxicity may necessitate discontinuation. Tafasitamab, which has modified anti-CD19 Fab and Fc regions, has significantly enhanced affinity for both CD19 and effector cell receptors compared with unmodified anti-CD19. In L-MIND, tafasitamab plus lenalidomide provided an overall response rate (ORR) of 57.5% in patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) in patients non-transplant eligible. Loncastuximab tesirine is an antibody–drug conjugate that has been studied as monotherapy and in combination with ibrutinib in 3L + relapsed or refractory DLBCL. The ORR was 48.3% in a phase II trial of loncastuximab tesirine. The optimal place of anti-CD19 monoclonal antibodies in therapy has yet to be determined, but the prospect of improved outcomes for at least some patients with treatment-resistant B-cell malignancies appears likely, particularly in those with limited therapeutic options and poor prognosis.

Regulation of platelet-activating factor receptor expression in human B cells and B cell lines

Lipids ◽  
1996 ◽  
Vol 31 (10) ◽  
pp. 1051-1058 ◽  
Author(s):  
Cheikh M. Nguer ◽  
Dominique Treton ◽  
Marek Rola-Pleszczynski ◽  
Zohair Mishal ◽  
Yolène Thomas ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Lines ◽  
Platelet Activating Factor ◽  
Receptor Expression ◽  
Human B Cells ◽  
Platelet Activating Factor Receptor

IgM+ B-Cells Lacking CD27 Expression Display Somatically Mutated Ig VH Genes and Define a New Memory Population.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2630-2630
Author(s):  
Nicola J. Weston-Bell ◽  
Mark R. Townsend ◽  
Francesco Forconi ◽  
Freda K. Stevenson ◽  
Surinder S. Sahota
Keyword(s):  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
Somatic Hypermutation ◽  
Gene Mutations ◽  
Memory B Cells ◽  
Cell Leukaemia ◽  
Germline Gene ◽  
Cell Of Origin ◽  
Class Switch

Abstract Somatic hypermutation (SHM) and isotype class switch recombination are critical mechanisms that diversify normal B-cells in response to antigen, and are generally confined to the germinal center (GC). Post-GC B-cells differentiate either into memory B-cells or antibody forming cells maturing as plasma cells. Memory B-cells which exit the GC have been regarded as invariably expressing CD27 and this population comprises both IgM+ and switched B-cells. It is, however, the presence of SHM that remains the defining feature of memory status in B-cells. Recently, it has been reported that dye extruding membrane ATP-binding transporters expressed by naive B-cells can distinguish them from memory B-cells which lack transporters and this, notably, led to the identification of IgG+ memory B-cells that did not express CD27. However, these observations were not correlated with SHM status. Here, we have examined these findings further and focused specifically on IgM+D+ B-cells in relation to our interest in mapping origins of B-cell tumors. Using dye-based transporter assays, we identified a substantial IgM+CD27− population in PBMNC from healthy individuals which lacked transporter activity. These cells were next isolated using a different strategy, employing IgD and CD27 expression, and a highly purified (>99%) IgD+CD27− fraction obtained by FACS sorting. There was virtually nil contamination by CD27+ B-cells. IgM transcripts were then specifically analyzed in this CD27− population for VH gene mutations by using Cmu downstream primers. We examined VH3 and VH5 gene transcripts from 2 separate sorts from a healthy donor following amplification by primary and nested RT-PCR and cloning products for sequence analysis. Of 104 VH3 clones from this CD27− fraction, 38 (37%) were germline and the remainder mutated (55% with 98–99.9% homology to germline, 9% <97.9%). Of these, 27% displayed 3–5 or more nucleotide mutations. Analysis of 124 VH5 clones from the same fraction showed 50% to be germline and the remainder mutated (45% with 98–99.9% homology, 5% <97.9%), of which 16% exhibited 3–5 or more mutations. Only 1 VH5 donor germline gene exists in the IgH repertoire, but 4 allelic variants which differ by 1 nucleotide are known. We mapped the VH5 germline gene in our donor using recombination sequence primers and only 1 allele was identified, identical to the donor gene mapped by database alignment, eliminating polymorphisms as a source of apparent base changes. Mutational load was also over and above a low level of PCR error which was quantified in the analysis. This confirmed that the levels of mutation detected in the rearranged VH5 transcripts in the IgM+D+CD27− population were generated by SHM. In contrast, between 74–90% of VH3 and VH5 transcripts from the IgM+D−CD27+ population were mutated, with a higher frequency of sequences (65–87%) displaying 3–5 or more mutations. Our data reveal the existence of a novel IgM+D+ population of normal B-cells which are somatically mutated but lack CD27. Unmutated IgM+D+ B-cells in this population point to heterogeneity in the CD27− B-cell pool. As yet, the clonal derivation of these mutated CD27− cells is undefined. Importantly, they have relevance for understanding the cell of origin in Hairy Cell leukaemia and Waldenstrom’s macroglobulinemia, where tumor cells are mutated yet lack CD27 expression.

Hairy Cell Leukaemia Displaying Multiple Surface Immunoglobulin Isotypes Reveal a Functional B-Cell Receptor In Which Isotype Roles Differ

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1567-1567
Author(s):  
Nicola J Weston-Bell ◽  
Gavin Babbage ◽  
Francesco Forconi ◽  
Hanneke C. Kluin-Nelemans ◽  
Surinder S Sahota
Keyword(s):  
B Cells ◽  
B Cell ◽  
Conflicts Of Interest ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Cell Leukaemia ◽  
Cross Linking ◽  
Hairy Cell ◽  
Surface Immunoglobulin

Abstract Abstract 1567 The B-cell receptor (BCR) is critical to survival of normal B-cells, and regulates key aspects of cellular behavior. Of these, response to antigen determines pathways of normal B-cell maturation, including isotype switch events that occur by deletional class switch recombination (CSR), an irrevocable event, to yield IgG/A memory B-cells. Less frequently, CSR via a cryptic site generates IgD+ B-cells whereas IgM+IgD+ antigen experienced B-cells synthesize each isotype by an alternative transcript splicing mechanism. The role of the BCR in survival of malignant B-cells however is less well defined, in particular in response to antigen. Intriguingly, in Hairy cell leukemia (HCL), BCR assembly occurs with multiple surface immunoglobulin (sIg) isotypes (mult-HCL), many co-expressed on individual hairy cells (HCs) in an otherwise monoclonal tumor. Multiple isotypes appear to exclude deletional CSR events, and suggests a RNA processing mechanism of molecular assembly. This phenotype is rare even amongst malignant B-cells, and raises the question of the functional relevance of individual variant isotypes. It also potentially presents a model to dissect roles of multiple isotypes on single B-cells. To examine this, we investigated the BCR in CD19+CD11c+CD103+ mult-HCL cases (n=10), in which 2–4 differing sIg isotypes were present on most HCs, with single or, in 3 cases, dual sIgL expression. In all cases, IGHV genes were mutated, and confirmed monoclonality. Phenotype revealed 2 distinct subsets by sIg isotype co-expression, IgD+ve and IgD-ve. Using Ca2+ flux and ERK phosphorylation assays after cross-linking with specific anti-sIg antibodies, we observed a functional BCR in all mult-HCL examined, in both subsets (10/10 cases Ca2+, 6/6 cases ERK). However, striking differences emerged between the two subsets. In sIgD+ve mult-HCL, IgD mediated persistent Ca2+ flux, with flux also evident via >1 sIgH isotype. In marked contrast, in sIgD-ve mult-HCL Ca2+ flux was restricted to a single sIgH isotype, but not via IgM. Flux signals in this subset were transient. In most cases only a single sIgL transduced flux. We next evaluated BCR endocytosis after cross-linking individual isotypes and IgL. In 2 sIgD+ve cases, anti-IgD and anti-Igλ stimulation led to endocytosis of both sIgD and sIgλ, and in 1 case, where examined, anti-IgM stimulation endocytosed both sIgM and sIgλ. In 3 sIgD-ve cases, functional sIgH and sIgL induced endocytosis of the stimulated isotype, but again sIgM was dysfunctional, remaining immobilized on the cell surface. Ca2+ flux through endocytosed isotypes was correspondingly either significantly reduced or ablated in both subsets. In HCs, BCR endocytosis is clearly dependent on functional isotypes and IgL, and parallels events in normal B-cells. Lastly, we examined downstream effects of BCR signalling on cell viability, using soluble (sAb) and bound (bAb) anti-sIg antibodies. In a single IgD+ve mult-HCL case, both sAb and bAb anti-IgM yielded a significant level of apoptosis compared to control antibodies, whereas anti-IgD sAb resulted in no appreciable difference to level of spontaneous apoptosis, suggesting a disengagement of signals from this pathway. This disengagement was also observed in a separate HCL case expressing only IgD, and not in the mult-HCL cohort initially selected, where anti-IgD signals again did not increase levels of apoptosis. In IgD-ve mult-HCL (n=4), sAb and bAb specific cross-linking of IgG/A triggered significant apoptosis. These data demonstrate, for the first time, that mult-HCL retains a functional responsiveness via the BCR, suggesting an absence of anergic effects that may follow chronic antigen exposure in-vivo to self-antigen. Signals via sIgM/G/A isotypes, where functional, induce apoptosis in mult-HCL, whereas sIgD opposes such effects. Despite an apparently unique molecular mechanism of IgD expression in mult-HCL, this isotype appears to be hardwired in B-cells to mediate responses that differ from IgM. The persistent flux observed here indicates a more sustained and robust IgD signaling cascade, as also observed in B-cell models. These data reveal distinctive and opposing effects of individual isotypes on BCR mediated behavior in mult-HCL. While apoptotic responses appear to negate a role for antigen in tumor drive in-vivo, potential antigen engagement via IgD, if dominant leaves this question open. Disclosures: No relevant conflicts of interest to declare.

B Cell Receptor with Variant Surface Isotypes Transduce Functional Signals by Elevating Phospho-ERK1/2 Levels in Hairy Cell Leukemia with Mutant BRAF

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1772-1772
Author(s):  
Nicola J Weston-Bell ◽  
Francesco Forconi ◽  
Hanneke C. Kluin-Nelemans ◽  
Surinder S Sahota
Keyword(s):  
B Cells ◽  
B Cell ◽  
Tumor Cells ◽  
Mapk Pathway ◽  
Cell Leukaemia ◽  
Initial Contact ◽  
Hairy Cell ◽  
Wild Type ◽  
Activation Markers ◽  
Mutant Braf

Abstract A functional BCR is essential for survival of normal B-cells, in response to cognate antigen or tonic, antigen-independent stimuli. Cross-linking of BCR by antigen triggers key phosphorylation events in the early signalosome. Mammalian wild type BRAF, a member of the RAF cytosolic kinase family (A-RAF, B-RAF, C-RAF) is critical to BCR function, mediating RAS-RAF-MEK-ERK or mitogen-activated protein kinase (MAPK) pathway signal transduction, via phosphorylation of ERK1/2. The MAPK pathway is a central conduit for survival and proliferation. Importantly, use of inducible deletion models have shown that wild type BRAF is the predominant kinase that transduces BCR signals to activate ERK1/2, with C-RAF playing an accessory role and A-RAF displaying a x20-30 fold lower basal activity in ERK1/2 stimulation. Tonic BCR survival signals in normal B-cells are also transduced via phosphorylation of ERK1/2, but do not require antigen stimuli. Whether the BCR plays a comparable role in sustaining survival in malignant B-cells is less well characterized and remains a central question in understanding the origins and progression of mature B-cell neoplasms. Hairy cell leukaemia (HCL) is a rare B cell leukaemia with characteristic hair-like cytoplasmic projections on tumor cells, displaying distinctive activation markers. A striking feature of monoclonal HCL tumors is expression of multiple variant immunoglobulin heavy chain (sIgH) isotypes as components of the BCR on individual tumor cells, defining the major subset of disease (mult-HCL). Most mult-HCL tumors exhibit IGV somatic hypermutation with a low level of on-going mutations and AID expressed, implicating initial contact with antigen via the BCR. The functional relevance of the BCR to transformation and survival however has as yet not been mapped in HCL. Seminal exome sequencing data in typical HCL identified mutant BRAF V(600)E as almost universal in this tumor. Consistent with mutant BRAFV(600)E, levels of phosphorylated ERK (p-ERK) are raised in hairy cells. As there is an essential requirement for wild type BRAF in transducing BCR signals, the question arises how mutant BRAF may affect BCR function in HCL, given requirements for dimerization of wild type BRAF for ERK1/2 activation, and whether ERK1/2 activation can be enhanced by functional BCR signals for downstream effector signals in HCL. To examine this, we evaluated BCR signalling in mult-HCL (n=10), in cases uniformly displaying mutated BRAF and IGHV genes. Two apparent functional sets were delineated by IgD co-expression. In sIgD+ mult-HCL, IgD mediated persistent Ca2+ flux, which was also evident via >1 sIgH isotype, linked to increased ERK1/2 activation and BCR endocytosis (4/4 cases). In sIgD-vemult-HCL however (6/6 cases), BCR-mediated signals activating ERK1/2 for downstream effects were restricted to a single sIgH isotype, with sIgM notably dysfunctional and remaining immobilised on the cell surface. These observations reveal a clear discordance between expression and function of individual isotypes in mult-HCL. In dual sIgL expressing mult-HCL (3/3 cases), only a single sIgL was fully functional. We next examined effects of anti-BCR stimuli on mult-HCL tumor cell survival ex-vivo. Significantly, all functional non-IgD isotypes increased ERK1/2 phosphorylation but triggered apoptosis of tumor cells, in both sets (4/4 cases) to establish a consistent outcome in these replicate cases. IgD stimuli, in marked contrast retained tumor viability with no evidence for pre-apoptotic effects (2 cases; 1 mult-HCL and 1 sIgD only-HCL). Despite mutant BRAF, BCR signals amplify ERK1/2 phosphorylation, but isotype dictates functional downstream outcomes. In mult-HCL lacking IgD, a role for antigen in stimulating the BCR for tumor persistence appears unlikely. It remains feasible that mutant BRAF in these cases retains tonic signals through activated ERK1/2 for survival, but this remains speculative at present. Surface IgD emerges with potential to transduce BCR signals for tumor survival and persistence in-vivo, but given its enigmatic role even in normal B-cells, its relevance to HCL progression is unclear. These observations raise the possibility that mutant BRAF may be a mechanism to bypass any antigen-dependent BCR signalling constraints in mult-HCL. Disclosures: No relevant conflicts of interest to declare.

Plasmalemma localisation of inorganic phosphate in B cells pancreas

1978 ◽  
Vol 36 (2) ◽  
pp. 528-529
Author(s):  
F. B. P. Wooding ◽  
K. Pedley ◽  
N. Freinkel ◽  
R. M. C. Dawson
Keyword(s):  
Electron Microscope ◽  
B Cells ◽  
B Cell ◽  
Pancreatic Islets ◽  
High Glucose ◽  
Lead Acetate ◽  
Inorganic Phosphate ◽  
Slight Modification ◽  
Uranyl Acetate ◽  
Lead Phosphate

Freinkel et al (1974) demonstrated that isolated perifused rat pancreatic islets reproduceably release up to 50% of their total inorganic phosphate when the concentration of glucose in the perifusion medium is raised.Using a slight modification of the Libanati and Tandler (1969) method for localising inorganic phosphate by fixation-precipitation with glutaraldehyde-lead acetate we can demonstrate there is a significant deposition of lead phosphate (identified by energy dispersive electron microscope microanalysis) at or on the plasmalemma of the B cell of the islets (Fig 1, 3). Islets after incubation in high glucose show very little precipitate at this or any other site (Fig 2). At higher magnification the precipitate seems to be intracellular (Fig 4) but since any use of osmium or uranyl acetate to increase membrane contrast removes the precipitate of lead phosphate it has not been possible to verify this as yet.

Lymphoproliferative disorders (LPD) involving lungs: T and B cell subsets within pulmonary infiltrates and in peripheral blood

1984 ◽  
Vol 42 ◽  
pp. 700-701
Author(s):  
Irene Stachura ◽  
Milton H. Dalbow ◽  
Michael J. Niemiec ◽  
Matias Pardo ◽  
Gurmukh Singh ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Lymphoproliferative Disorders ◽  
Mixed Population ◽  
Lymphoid Cells ◽  
Lymphomatoid Granulomatosis ◽  
Cell Type ◽  
Cell Surface Antigens ◽  
Pulmonary Infiltrates ◽  
B Cell Subsets

Lymphoid cells were analyzed within pulmonary infiltrates of six patients with lymphoproliferative disorders involving lungs by immunofluorescence and immunoperoxidase techniques utilizing monoclonal antibodies to cell surface antigens T11 (total T), T4 (inducer/helper T), T8 (cytotoxic/suppressor T) and B1 (B cells) and the antisera against heavy (G,A,M) and light (kappa, lambda) immunoglobulin chains. Three patients had pseudolymphoma, two patients had lymphoma and one patient had lymphomatoid granulomatosis.A mixed population of cells was present in tissue infiltrates from the three patients with pseudolymphoma, IgM-kappa producing cells constituted the main B cell type in one patient. In two patients with lymphoma pattern the infiltrates were composed exclusively of T4+ cells and IgG-lambda B cells predominated slightly in the patient with lymphomatoid granulomatosis.

B-cell and T-cell values in peripheral blood in Polish mixed-breed rabbits with addition of blood of meet breeds

2014 ◽  
Vol 17 (3) ◽  
pp. 421-426 ◽  
Author(s):  
B. Tokarz-Deptuła ◽  
P. Niedźwiedzka-Rystwej ◽  
B. Hukowska-Szematowicz ◽  
M. Adamiak ◽  
A. Trzeciak-Ryczek ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cd8 T Cells ◽  
Peripheral Blood ◽  
Laboratory Animals ◽  
Immunological Parameters ◽  
Four Seasons ◽  
Mixed Breed ◽  
The Impact

Abstract In Poland, rabbit is a highly valued animal, due to dietetic and flavour values of its meat, but above all, rabbits tend to be commonly used laboratory animals. The aim of the study was developing standards for counts of B-cells with CD19+ receptor, T-cells with CD5+ receptor, and their subpopulations, namely T-cells with CD4+, CD8+ and CD25+ receptor in the peripheral blood of mixed-breed Polish rabbits with addition of blood of meet breeds, including the assessment of the impact of four seasons of the year and animal sex on the values of the immunological parameters determined. The results showed that the counts of B- and T-cells and their subpopulations in peripheral blood remain within the following ranges: for CD19+ B-cells: 1.05 - 3.05%, for CD5+ T-cells: 34.00 - 43.07%, CD4+ T-cells: 23.52 - 33.23%, CD8+ T-cells: 12.55 - 17.30%, whereas for CD25+ T-cells: 0.72 - 2.81%. As it comes to the season of the year, it was observed that it principally affects the values of CD25+ T-cells, while in the case of rabbit sex, more changes were found in females.

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