scholarly journals Natural ligands of the B cell adhesion molecule CD22 beta can be masked by 9-O-acetylation of sialic acids.

1994 ◽  
Vol 126 (2) ◽  
pp. 549-562 ◽  
Author(s):  
E R Sjoberg ◽  
L D Powell ◽  
A Klein ◽  
A Varki
Keyword(s):  
Dendritic Cells ◽  
Lymph Node ◽  
B Cells ◽  
B Cell ◽  
Sialic Acids ◽  
Lymphoid Cells ◽  
Side Chain ◽  
Adhesion Assay ◽  
In Vitro Adhesion

CD22 beta is a B cell-restricted phosphoprotein expressed on the surface of mature resting B cells. It mediates interactions with other cells partly or exclusively via recognition of alpha 2-6-linked sialic acids on glycoconjugates. The sialylated N-linked oligosaccharides recognized best by CD22 beta are common to many glycoproteins, suggesting that additional regulatory mechanisms may exist. Since the exocyclic side chain of sialic acid is required for recognition, we explored the effects of a naturally occurring modification of the side chain, 9-O-acetylation. Semisynthetic N-linked oligosaccharides terminating with 9-O-acetylated, alpha 2-6-linked sialic acids showed markedly reduced binding to CD22 beta relative to their non-O-acetylated counterparts. Murine lymphoid cells were probed for natural CD22 beta ligands that might be O-acetylated using recombinant soluble forms of CD22 beta (CD22 beta Rg) and influenza C esterase (CHE-Fc, which specifically removes 9-O-acetyl esters from sialic acids). By flow cytometry analysis, CD22 beta Rg binding to splenic B cells and a subset of T cells was increased by pretreatment with CHE-Fc, indicating that some potential CD22 beta ligands are naturally "masked" by 9-O-acetylation. Unmasking of these CD22 beta ligands by removal of 9-O-acetyl esters from intact splenocytes substantially increases their CD22 beta-dependent adhesion in an in vitro adhesion assay. Probing of murine lymphoid tissue sections by CD22 beta Rg and CHE-Fc treatment demonstrates regionally restricted and differentially expressed patterns of distribution between masked and unmasked ligands. For example, lymph node-associated follicular B cells express high levels of CD22 beta ligands, none of which are masked by 9-O-acetylation. In contrast, the ligands on lymph node-associated dendritic cells are almost completely masked by 9-O-acetylation, suggesting that masking may regulate interactions between CD22 beta-positive B cells and dendritic cells. In the thymus, only medullary cells express CD22 beta ligands, and a significant portion of these are masked by 9-O-acetylation, particularly at the cortical-medullary junction. Thus, 9-O-acetylation of sialic acids on immune cells is in a position to negatively regulate CD22 beta adhesion events in a manner depending on both cell type and tissue localization.

scholarly journals Monoclonal antibodies to the 140,000 mol wt glycoprotein of B lymphocyte membranes (CR2 receptor) initiates proliferation of B cells in vitro

Blood ◽  
1985 ◽  
Vol 66 (4) ◽  
pp. 824-829
Author(s):  
BS Wilson ◽  
JL Platt ◽  
NE Kay
Keyword(s):  
Monoclonal Antibodies ◽  
B Cells ◽  
B Cell ◽  
Peripheral Blood ◽  
B Lymphocyte ◽  
Human Peripheral Blood ◽  
Raji Cell ◽  
Lymphoid Cells ◽  
Humoral Immune

Several mouse monoclonal IgG antibodies (AB1, AB2, AB3, and AB5) were developed that reacted with a 140,000 mol wt glycoprotein on the surface of cultured RAJI B lymphoid cells. The antibodies reacted with purified normal human peripheral blood B cells and CLL Ig+ B cells and showed specific germinal center and mantle zone staining in tissue sections of secondary lymphoid organs. Immunodepletion studies using 125I surface-labeled Raji cell membrane antigens demonstrated that the antigen identified by AB5 is the same 140,000 mol wt glycoprotein detected by anti-B2 that has recently been shown to react with the C3d fragment or CR2 receptor. (Iida et al: J Exp Med 158:1021, 1983). Addition of the AB series and anti-B2 monoclonal antibodies to cultures of purified human peripheral blood B cells resulted in the uptake of 3H- thymidine at two to six times background control levels provided that irradiated autologous T cells were added to the culture. Stimulation was not evoked by other monoclonal antibodies to B cell surface molecules (ie, B1, BA-1, BA-2, and HLA-DR). Pepsin-generated F(ab')2 fragments of anti-CR2 antibodies were essentially as effective as the intact IgG molecule in stimulating B cells. Induction of B cell proliferation by antibody binding to CR2 suggests that the C3d receptor may have an integral role in regulation of humoral immune response.

Mucosal Epithelial Cells Initiate Frontline Immunoglobulin Class Switching through an SLPI-Regulated Pathway.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3898-3898
Author(s):  
Andrea Cerutti ◽  
Bing He ◽  
April Chiu ◽  
Meimei Shan ◽  
Paul Santini ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
B Cells ◽  
Epithelial Cells ◽  
B Cell ◽  
Antibody Production ◽  
Cytidine Deaminase ◽  
Dna Recombination ◽  
Class Switching ◽  
Class Switch

Abstract Introduction. Class switching from IgM to IgG and IgA is central to immunity against microbes and usually occurs in draining lymph nodes and requires activation of B cells by CD4+ T cells expressing CD40 ligand. Growing evidence indicates that B cells can mount frontline IgG and IgA responses at mucosal sites of entry through an alternative CD40-independent pathway involving B cell-activating factor of the TNF family (BAFF, also known as BLyS) and a proliferation-inducing ligand (APRIL). These innate factors are usually produced by dendritic cells and stimulate B cells through at least three distinct receptors. Together with dendritic cells, epithelial cells have a key position at the host-environment interface. Therefore, we asked whether epithelial cells play a role in frontline antibody production. Methods. Tonsillar tissue sections from healthy donors were analyzed for expression of activation-induced cytidine deaminase (AID) by immunohistochemistry and in situ hybridization. A simplified in vitro model reproducing the geometry of mucosal surfaces was used to evaluate the role of epithelial cells in class switching. Briefly, primary epithelial cells and B cells were cultured in the upper and lower chambers, respectively, of a trans-well system. Monocyte-derived dendritic cells were positioned on a filter separating the two chambers. Various microbial product analogues were used to mimic infection. RNA interference was performed to knockdown BAFF in epithelial cells. AID expression, CSR, antibody production and signaling were evaluated in B cells as reported (Litinsky et al., Nat. Immunol.2002, 3:822–829; Qiao et al., Nat. Immunol.2006, 7:302–310). Results. We found that the upper respiratory mucosa of healthy subjects comprised intraepithelial pockets filled with B cells expressing AID, a DNA-editing enzyme associated with ongoing class switch DNA recombination (CSR). Epithelial cells released innate class switch-inducing factors, including BAFF, after sensing microbial products through TLRs, thereby inducing AID expression, CSR, and ultimately IgG and IgA production in neighboring B cells. Epithelial cell-induced antibodies comprised polyreactive IgG and IgA capable of recognizing multiple microbial determinants. Intraepithelial class switching was enhanced by thymic stromal lymphopoietin (TSLP), an epithelial IL-7-like cytokine that augments the innate B cell-licensing functions of dendritic cells, and restrained by secretory leukocyte protease inhibitor (SLPI), an epithelial alarm antiprotease that suppresses AID expression in activated B cells. Conclusions. The present findings indicate that epithelial cells function as non-immune sentinels capable to autonomously orchestrate compartmentalized IgG and IgA responses at the interface between host and environment. This implies that mucosal vaccines should activate both epithelial and immune cells to elicit optimal antibody production.

scholarly journals Autoreactive marginal zone B cells are spontaneously activated but lymph node B cells require T cell help

2006 ◽  
Vol 203 (8) ◽  
pp. 1985-1998 ◽  
Author(s):  
Laura Mandik-Nayak ◽  
Jennifer Racz ◽  
Barry P. Sleckman ◽  
Paul M. Allen
Keyword(s):  
Lymph Node ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Marginal Zone ◽  
B Cell Tolerance ◽  
Marginal Zone B Cells ◽  
T Cell Help

In K/BxN mice, arthritis is induced by autoantibodies against glucose-6-phosphate-isomerase (GPI). To investigate B cell tolerance to GPI in nonautoimmune mice, we increased the GPI-reactive B cell frequency using a low affinity anti-GPI H chain transgene. Surprisingly, anti-GPI B cells were not tolerant to this ubiquitously expressed and circulating autoantigen. Instead, they were found in two functionally distinct compartments: an activated population in the splenic marginal zone (MZ) and an antigenically ignorant one in the recirculating follicular/lymph node (LN) pool. This difference in activation was due to increased autoantigen availability in the MZ. Importantly, the LN anti-GPI B cells remained functionally competent and could be induced to secrete autoantibodies in response to cognate T cell help in vitro and in vivo. Therefore, our study of low affinity autoreactive B cells reveals two distinct but potentially concurrent mechanisms for their activation, of which one is T cell dependent and the other is T cell independent.

scholarly journals CD73 mediates adhesion of B cells to follicular dendritic cells

Blood ◽  
1996 ◽  
Vol 88 (5) ◽  
pp. 1755-1764 ◽  
Author(s):  
L Airas ◽  
S Jalkanen
Keyword(s):  
Dendritic Cells ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Intracellular Signaling ◽  
Follicular Dendritic Cells ◽  
Adhesion Protein ◽  
Follicular Dendritic ◽  
Vascular Adhesion

Abstract Lymphocyte-vascular adhesion protein-2 was recently identified as CD73. The CD73 molecule, otherwise known as ecto-5′-nucleotidase, is a lymphocyte maturation marker that is involved in intracellular signaling, and lymphocyte proliferation and activation. We now show that CD73, in addition to mediating lymphocyte binding to endothelial cells, also mediates adhesion between B cells and follicular dendritic cells (FDC), as a monoclonal antibody (MoAb) against CD73 inhibited the aggregation of isolated germinal center B cells and FDC in vitro. Cytocentrifuge preparations of isolated germinal center cells and two- color immunofluorescence stainings of different tonsillar B-cell populations show that CD73 is expressed on FDC and on small, recirculating IgD+ B cells, but only on a few B cells inside the germinal center. Thus, we propose that CD73 on FDC has an important role in controlling B cell-FDC interactions and B-cell maturation in germinal centers.

scholarly journals Monoclonal antibodies to the 140,000 mol wt glycoprotein of B lymphocyte membranes (CR2 receptor) initiates proliferation of B cells in vitro

Blood ◽  
1985 ◽  
Vol 66 (4) ◽  
pp. 824-829 ◽  
Author(s):  
BS Wilson ◽  
JL Platt ◽  
NE Kay
Keyword(s):  
Monoclonal Antibodies ◽  
B Cells ◽  
B Cell ◽  
Peripheral Blood ◽  
B Lymphocyte ◽  
Human Peripheral Blood ◽  
Raji Cell ◽  
Lymphoid Cells ◽  
Humoral Immune

Abstract Several mouse monoclonal IgG antibodies (AB1, AB2, AB3, and AB5) were developed that reacted with a 140,000 mol wt glycoprotein on the surface of cultured RAJI B lymphoid cells. The antibodies reacted with purified normal human peripheral blood B cells and CLL Ig+ B cells and showed specific germinal center and mantle zone staining in tissue sections of secondary lymphoid organs. Immunodepletion studies using 125I surface-labeled Raji cell membrane antigens demonstrated that the antigen identified by AB5 is the same 140,000 mol wt glycoprotein detected by anti-B2 that has recently been shown to react with the C3d fragment or CR2 receptor. (Iida et al: J Exp Med 158:1021, 1983). Addition of the AB series and anti-B2 monoclonal antibodies to cultures of purified human peripheral blood B cells resulted in the uptake of 3H- thymidine at two to six times background control levels provided that irradiated autologous T cells were added to the culture. Stimulation was not evoked by other monoclonal antibodies to B cell surface molecules (ie, B1, BA-1, BA-2, and HLA-DR). Pepsin-generated F(ab')2 fragments of anti-CR2 antibodies were essentially as effective as the intact IgG molecule in stimulating B cells. Induction of B cell proliferation by antibody binding to CR2 suggests that the C3d receptor may have an integral role in regulation of humoral immune response.

scholarly journals Pre-B-cells in normal human bone marrow and in bone marrow from patients with leukemia in remission: persistent quantitative differences and possible expression of cell surface IgM in vitro

Blood ◽  
1983 ◽  
Vol 61 (3) ◽  
pp. 464-468 ◽  
Author(s):  
ER Pearl
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
Acute Leukemia ◽  
B Cell ◽  
Solid Tumors ◽  
B Lymphocytes ◽  
Lymphoid Cells ◽  
Barr Virus ◽  
Marrow Cells

Abstract Pre-B-cells are bone marrow lymphoid cells that lack surface immunoglobulin (sIg-) but contain intracytoplasmic (c) IgM heavy chains and are probably the immediate precursors of immature sIgM+ B lymphocytes. To better understand early stages of B-cell development, immunofluorescence techniques were employed to identify pre-B-cells and B lymphocytes and to examine the expression of sIgM in vitro by human marrow that had been previously depleted of B cells by immunoadsorption. Marrow was derived from patients with acute leukemia in long-term remission off therapy and from a variety of controls. The pre-B-cell compartment was greatly expanded in the marrow of leukemia remission patients for more than 2 yr following cessation of therapy. A similar finding was noted in two patients with lymphoma who had also completed chemotherapy, but not in three with solid tumors prior to therapy. sIgM+ B cells appeared in cultures of sIg- marrow cells from leukemia patients, but not the controls, and only after exposure to Epstein-Barr virus (EBV). At least some of the sIgM+ lymphocytes also expressed cIgM and were probably derived from pre-B-cells. The results of this study (A) confirm that patients who have completed treatment for acute leukemia have a prolonged elevation of pre-B-cell proportions, (B) demonstrate that similar abnormalities may exist in patients with certain solid tumors following chemotherapy, and (C) suggest that a fraction of sIg- human marrow cells, perhaps pre-B- cells, bear a receptor for EBV and can be induced to express to sIgM in vitro.

scholarly journals Human Dendritic Cells Skew Isotype Switching of CD40-activated Naive B Cells towards IgA1 and IgA2

1997 ◽  
Vol 185 (11) ◽  
pp. 1909-1918 ◽  
Author(s):  
Jérôme Fayette ◽  
Bertrand Dubois ◽  
Stéphane Vandenabeele ◽  
Jean-Michel Bridon ◽  
Béatrice Vanbervliet ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Culture Conditions ◽  
Lymphoid Organs ◽  
Cell Growth And Differentiation ◽  
Secondary Lymphoid Organs

Within T cell–rich areas of secondary lymphoid organs, interdigitating dendritic cells recruit antigen-specific T cells that then induce B cells to secrete Igs. This study investigates the possible role(s) of dendritic cells in the regulation of human B cell responses. In the absence of exogenous cytokines, in vitro generated dendritic cells (referred to as Dendritic Langerhans cells, D-Lc) induced surface IgA expression on ∼10% of CD40-activated naive sIgD+ B cells. In the presence of IL-10 and TGF-β, a combination of cytokines previously identified for its capacity to induce IgA switch, D-Lc strongly potentiated the induction of sIgA on CD40-activated naive B cells from 5% to 40–50%. D-Lc alone did not induce the secretion of IgA by CD40-activated naive B cells, which required further addition of IL-10. Furthermore, D-Lc skewed towards the IgA isotype at the expense of IgG, the Ig production of CD40-activated naive B cells cultured in the presence of IL-10 and TGF-β. Importantly, under these culture conditions, both IgA1 and IgA2 were detected. In the presence of IL-10, secretion of IgA2 by CD40-activated naive B cells could be detected only in response to D-Lc and was further enhanced by TGF-β. Collectively, these results suggest that in addition to activating T cells in the extrafollicular areas of secondary lymphoid organs, human D-Lc also directly modulate T cell–dependent B cell growth and differentiation, by inducing the IgA isotype switch.

Macrophage- and dendritic cell—dependent regulation of human B-cell proliferation requires the TNF family ligand BAFF

Blood ◽  
2003 ◽  
Vol 101 (11) ◽  
pp. 4464-4471 ◽  
Author(s):  
Andrew Craxton ◽  
Dario Magaletti ◽  
Elizabeth J. Ryan ◽  
Edward A. Clark
Keyword(s):  
Cell Proliferation ◽  
Dendritic Cells ◽  
B Cells ◽  
Dendritic Cell ◽  
B Cell ◽  
B Cell Antigen Receptor ◽  
Human Macrophages ◽  
Cell Responses ◽  
Human B Cell

Abstract Macrophages and dendritic cells play an important role in regulating B-cell responses, including proliferation to antigens such as trinitrophenyl (TNP)—Ficoll and TNP-Brucella abortus. However, the mechanisms and molecule(s) that regulate these processes are relatively undefined. In this report, we show that human macrophages generated in vitro strongly costimulate proliferation of dense human tonsillar B cells ligated via their B-cell antigen receptor (BCR) but not proliferation via CD40. Similarly, dendritic cells also markedly enhance BCR-activated B-cell proliferation. Soluble molecule(s) are required for human macrophages to costimulate proliferation of B cells triggered via their BCR. Importantly, a TACI (trans-membrane activator and CAML interactor)—Fc fusion protein inhibits both macrophage- and dendritic cell (DC)—dependent BCR-activated B-cell proliferation, indicating a requirement for at least one of the known TACI ligands, BAFF and/or APRIL. Consistent with a major role for BAFF, macrophages release BAFF at levels sufficient to potently costimulate BCR-induced B-cell proliferation. In addition, BAFF is more than 100-fold more potent than APRIL in enhancing BCR-mediated human B-cell proliferation. Furthermore, immunodepletion of APRIL under conditions that prevent APRIL-mediated B-cell costimulation does not block macrophage enhancement of B-cell proliferation. Finally, there is no correlation between the high levels of a proliferation-inducing ligand (APRIL) expressed by macrophages compared with DCs and the similar abilities of macrophages and DCs to enhance BCR-stimulated B-cell proliferation. In summary, our results suggest that macrophage- and DC-derived B-cell—activating factor belonging to the TNF family (BAFF) represents a key molecule by which macrophages and DCs directly regulate human B-cell proliferative responses to T-cell—independent stimuli.

scholarly journals Pre-B-cells in normal human bone marrow and in bone marrow from patients with leukemia in remission: persistent quantitative differences and possible expression of cell surface IgM in vitro

Blood ◽  
1983 ◽  
Vol 61 (3) ◽  
pp. 464-468
Author(s):  
ER Pearl
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
Acute Leukemia ◽  
B Cell ◽  
Solid Tumors ◽  
B Lymphocytes ◽  
Lymphoid Cells ◽  
Barr Virus ◽  
Marrow Cells

Pre-B-cells are bone marrow lymphoid cells that lack surface immunoglobulin (sIg-) but contain intracytoplasmic (c) IgM heavy chains and are probably the immediate precursors of immature sIgM+ B lymphocytes. To better understand early stages of B-cell development, immunofluorescence techniques were employed to identify pre-B-cells and B lymphocytes and to examine the expression of sIgM in vitro by human marrow that had been previously depleted of B cells by immunoadsorption. Marrow was derived from patients with acute leukemia in long-term remission off therapy and from a variety of controls. The pre-B-cell compartment was greatly expanded in the marrow of leukemia remission patients for more than 2 yr following cessation of therapy. A similar finding was noted in two patients with lymphoma who had also completed chemotherapy, but not in three with solid tumors prior to therapy. sIgM+ B cells appeared in cultures of sIg- marrow cells from leukemia patients, but not the controls, and only after exposure to Epstein-Barr virus (EBV). At least some of the sIgM+ lymphocytes also expressed cIgM and were probably derived from pre-B-cells. The results of this study (A) confirm that patients who have completed treatment for acute leukemia have a prolonged elevation of pre-B-cell proportions, (B) demonstrate that similar abnormalities may exist in patients with certain solid tumors following chemotherapy, and (C) suggest that a fraction of sIg- human marrow cells, perhaps pre-B- cells, bear a receptor for EBV and can be induced to express to sIgM in vitro.

scholarly journals L2C Guinea Pig Lymphatic Leukemia: A "B" Cell Leukemia

Blood ◽  
1972 ◽  
Vol 39 (1) ◽  
pp. 1-12 ◽  
Author(s):  
E. M. Shevach ◽  
L. Ellman ◽  
J. M. Davie ◽  
I. Green
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Guinea Pig ◽  
B Cell ◽  
B Lymphocyte ◽  
Lymphoid Cells ◽  
Cell Mediated Immunity ◽  
Lymphatic Leukemia

Abstract Lymphoid cells of the immune system can be divided into two functional compartments. The thymus derived population, "T" cells, is responsible for cell mediated immunity. The bone marrow derived population, "B" cells, is responsible for antibody production. Although these two populations are functionally different, it has not yet been possible to distinguish them morphologically. Recent experimental work in the mouse has shown that the B cells bear easily detectable immunoglobulin. The T cells can be distinguished by the isoantigen, theta. The B or T cell origin of the lymphocytes of human or animal leukemia has received little attention. In the present study, we have examined the functional and morphologic properties of a guinea pig lymphatic leukemia L2C. L2C cells secrete T2 immunoglobulin and also bear this immunoglobulin on their surface. L2C cells have the recently described lymphocyte receptor for antigen-antibody-complement complexes (found on normal B lymphocytes). Finally, the L2C cell fails to be stimulated in vitro by mitogens capable of stimulating thymus-derived lymphocytes. Thus, the L2C cell appears to be of B lymphocyte origin. The availability of a large number of pure B lymphoid cells will provide a useful tool for the study of the cellular receptors of lymphoid cells and for the preparation of antisera specific for the T cell and B cell populations. The application of the techniques described in this paper to classify other lymphoid neoplasms as to their T or B cell origin may lead to both theoretic and therapeutic advances.

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