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PubMed1995

B lymphocytes with latent EBV infection appearing in long-term bone marrow cultures (HLTBMCs) from haematological patients induce lysis of stromal microenvironment.

Human long-term bone marrow cultures (HLTBMCs) are a valuable in vitro model for studying the role of the haemopoietic microenvironment. Here we report the spontaneous appearance of EBV-positive B cells in 6/40 HLTBMCs from patients with various haematological diseases after 3-5 months of culture. After subcultivation of these cells, a novel type of cell line could be characterized, which displayed surface markers and morphological features typical for EBV transformed B-cell lines. As the deproteinized and ultrafiltrated culture supernatants of these cell lines were found to contain an agent with stroma toxic properties, they were termed SSB lines (stroma-toxic-agent-secreting B-cell lines). This agent also exhibited a colony-inhibitory activity on in vitro myelopoiesis and erythropoiesis. These properties are typical for the two polyamines spermine and spermidine which were detected at elevated levels in the culture supernatants of SSB lines. The hypothesis that latent presence of EBV in bone marrow may induce an increased synthesis of spermine and spermidine, which are known to be associated with malignant haematological diseases and bone marrow aplasia, is discussed.

B-Lymphocytes↗
PubMed1995

Effect of an asthmatic attack on CD23 and CD21 expression on lymphocytes from allergic children during the allergen season.

BACKGROUND: The overproduction of IgE antibodies by atopic individuals in response to inhaled aeroallergen, forms the basis of an allergic disease. Furthermore, the exposure to allergen might trigger the symptom exacerbation. OBJECTIVE: In children with bronchial asthma, the possible effects of seasonal, natural exposure to allergen on the expression of CD21 and CD23 antigens on B lymphocytes, and on the expression of HLA-DR, CD45RA and CD45RO on CD4+ T cells investigated. METHODS: Heparinized blood samples were obtained from 15 children with bronchial asthma allergic to Dermatophagoides pteronyssinus (Der p) at the time of an acute asthmatic attack and 2-4 weeks after the attack when the peak expiratory flow (PEF) was stabilized. The samples were analysed on a flow cytometer after the three-colour immunofluorescence staining had been performed. RESULTS: The increased proportion of B cells expressing CD23 antigen was found at the time of attack rather than after stabilization. Serum levels of total and Der p-specific IgE increased 2-4 weeks after the asthmatic attack. This increase was accompanied by a further increase in the expression of CD23 antigen on CD21- B lymphocytes. In 10 out of 15 tested children, we found CD23 expressed on CD4+HLA-DR+ T cells during the asthmatic attack. No significant difference was found in the expression of CD45RA and CD45RO. CONCLUSION: Since we have previously demonstrated the increased percentage of CD23 on CD21- B cells in allergic children as compared with controls, we speculate that natural exposure to the allergen which caused the increase in total and specific IgE levels might be related to the increased expression of CD23 on CD21- B cells.

Adolescent↗
PubMed1993

CD21-CD23 ligand pair expression in children with allergic asthma.

The CD23 antigen, a low affinity receptor for IgE, was recently shown to interact with another ligand, CD21, and the pairing of these molecules is important in T cell-B cell interaction and control of IgE production. Here, we analysed the expression of CD21 and CD23 on CD4+ and CD20+ lymphocytes in 25 allergic children and 12 age-matched non-allergic controls. Both the percentage (P < 0.01) and the absolute number (P < 0.001) of CD23+ cells were increased in allergic children. There was no difference of CD21+ cells. Double positive CD4+ CD23+ cells (2.5%) were only detected in one patient, in others all CD23 being expressed on B cells. The CD21 antigen was expressed only on B cells. Furthermore, allergic children had an increased mean fluorescence intensity of both the CD21 (P < 0.001) and the CD23 (P < 0.001) receptor. To analyse the possible difference in B cell subsets expressing CD21 and CD23 antigens, three-colour fluorescence analysis was performed. In allergic children the subset of CD20+ CD21- cells expressed more CD23 than in controls (P < 0.001). These results may mean an impaired expression and possibly regulation of CD21-CD23 interaction in allergic conditions.

Adolescent↗
PubMed2006

Cellular inflammatory response to persistent localized Staphylococcus aureus infection: phenotypical and functional characterization of polymorphonuclear neutrophils (PMN).

Persistent, localized Staphylococcus aureus infections, refractory to antibiotic treatment, can result in massive tissue destruction and surgical intervention is often the only therapeutic option. In that context, we investigated patients with S. aureus-induced infection at various sites, apparent as either olecranon bursitis, empyema of the knee joint or soft tissue abscess formation. As expected, a prominent leucocyte infiltrate was found, consisting predominantly of polymorphonuclear neutrophils (PMN) (up to 75%) and to a lesser extent of T lymphocytes and natural killer (NK) cells. In line with their bactericidal capacity, PMN expressed the high-affinity receptor for IgG, CD64 and the lipopolysaccharide (LPS) receptor CD14; moreover, the oxygen radical production in response to the bacterial peptide f-MLP was enhanced, while chemotactic activity was greatly reduced. The more intriguing finding, however, was that a portion of PMN had acquired major histocompatibility complex (MHC) class II antigens and CD83, indicative of a transdifferentiation of PMN to cells with dendritic-like characteristics. Of note is that a similar transdifferentiation can be induced in PMN in vitro, e.g. by gamma interferon or by tumour necrosis factor alpha. Co-cultivation of transdifferentiated PMN with autologous T lymphocytes resulted in prominent T cell proliferation, provided that S. aureus enterotoxin A was added. Taken together, persistent S. aureus infection induces PMN to acquire characteristics of dendritic cells, which in turn might promote the local immune response.

Aged↗
PubMed1992

Epstein-Barr virus DNA in Reed-Sternberg cells of Hodgkin's disease is frequently associated with CR2 (EBV receptor) expression.

We studied 44 cases of Hodgkin's disease for the presence of Epstein-Barr virus (EBV) DNA, its localization and the expression of the EBV receptor on the tumour cells. EBV DNA was found in 52% (16/31) of the Hodgkin's lymphomas using the polymerase chain reaction. With a very sensitive non-radioactive DNA in situ hybridization technique in combination with immunohistochemistry for CD 30 or CD 15 antigens, EBV DNA was localized to Reed-Sternberg cells and its mononuclear variants. The relationship between the presence of EBV DNA and the expression of the EBV-receptor CR2 (CD 21) on Reed-Sternberg cells was studied using the same techniques and two different monoclonal anti-CD 21 antibodies. CR2 could be detected on a substantial number of the Reed-Sternberg cells in EBV DNA positive Hodgkin's lymphomas (9/12; 75%), whereas in EBV negative cases positivity with anti-CD 21 was rare (1/13; 8%). The results indicate that CR2 expression on Reed-Sternberg cells and the presence of EBV DNA sequences are frequently associated in Hodgkin's lymphomas.

Antigens, Differentiation, B-Lymphocyte↗
PubMed2005

Complement receptors regulate lipopolysaccharide-induced T-cell stimulation.

Complement receptors type 1 and 2 (CR1 (CD35)/CR2 (CD21)) are known to enhance the adaptive immune response. In mice, CR1/CR2 are expressed on B cells, follicular dendritic cells, and activated granulocytes. Recently, we showed that a subset of CD44high and CD62Llow T cells also expresses CR1 and CR2. We now report that CR1/CR2 are detectable on both CD4+ and CD8+ subsets of T cells. Lipopolysaccharide (LPS) from Gram-negative bacteria causes polyclonal activation of B cells and stimulation of macrophages and other antigen-presenting cells. We further demonstrate that LPS induced marked up-regulation of CD25 and CD69 on T cells from CR1/CR2 sufficient (Cr+/+), but significantly lower up-regulation on T cells from CR1/CR2 deficient (Cr-/-) mice. These findings point to a novel mechanism by which CR1/CR2 modulates the activation of T cells by LPS.

Animals↗
PubMed1997

Expression of CD23 antigen and its ligands in children with intrinsic and extrinsic asthma.

The role of the low-affinity IgE receptor CD23 in immune reactions has been further emphasized by recent discoveries of novel surface ligands for CD23: CD21, CD11b, and CD11c. We previously observed the difference between the expression of CD23 and CD21 antigens in children suffering from extrinsic asthma when compared to healthy controls. In the present study, we investigated the expression of CD23 and its ligand CD21 on CD20 B cells in 44 asthmatic children (23 allergic and 21 nonallergic) using three-color immunofluorescence analysis. In addition, the expression of two other ligands for CD23, CD11b, and CD11c, on T cells (CD3+), a subpopulation of T cells (CD4+ and CD8+), natural killer cells (CD56+), and monocytes (CD14+) was tested by two-color immunofluorescence analysis in 12 allergic and 14 nonallergic children. We found that children with extrinsic asthma had higher levels of CD23+ B cells than those with intrinsic asthma. No difference was observed in the percentage of either CD23+CD21+ or CD23-CD21+ B cells. The CD11b antigen was expressed on each tested population, but only on CD4+ T cells was CD11b significantly increased in children with extrinsic asthma. CD11c was expressed mainly on monocytes, and no difference was observed between tested groups. The increased percentage of CD11b antigen on CD4+ T cells and the increased percentage of CD23 antigen on B cells in children with extrinsic asthma provide further evidence of the immunologic differences between intrinsic and extrinsic asthma.

Adolescent↗
PubMed1991

Phenotypic analysis of B-cells extracted from human periodontal disease tissue.

B-cells extracted from periodontal disease tissue were analyzed for the presence of activation markers using a range of monoclonal antibodies. In adult periodontitis (AP), 6% of B-cells expressed the IL-2 receptor (CD25) compared with 1-2% in peripheral blood and healthy or marginal gingivitis (H/MG) gingival B-cells. There was also an increase in the mean percentage of IgD-positive B-cells and a decrease in CD21 and CD22 expression. In both AP and H/MG lesions, 20-22% of the B-cells expressed CD23 compared with less than 5% in peripheral blood. As B-cells are activated by day 3 in culture and start differentiating into immunoglobulin-secreting cells by day 6, B-cell phenotypes were assayed at these times in this study. Following stimulation with the periodontopathic bacterium Porphyromonas gingivalis, the expression of CD23, CD21 and CD22 on B-cells extracted from AP lesions remained relatively constant over the 6-d culture period. However, with Fusobacterium nucleatum stimulation, there was a significant decrease in CD23, CD21 and CD22 expression after 3 d in culture, which corresponds to the activation time for B-cells. These results show that B-cells extracted from periodontal disease tissue display a range of activation markers and on stimulation, demonstrate differing responses to individual periodontopathic bacteria.

Adult↗
PubMed1999

Expression of the mucosal vascular addressin, MAdCAM-1, in inflammatory liver disease.

AIMS/BACKGROUND: The integrin alpha4beta7 and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) are involved in normal recirculation of lymphocytes between the blood and the tissues of the gastrointestinal tract. In this study we have examined the expression of MAdCAM-1 in human liver. METHODS: MAdCAM-1 expression was determined in archival human liver tissues by immunohistochemistry. RESULTS: While MAdCAM-1 was not detected in normal fetal or adult human liver, expression was observed in association with portal tract inflammation in a variety of liver diseases. Detailed analysis of liver biopsies from patients with hepatitis C showed a positive correlation between the portal/periportal component of the histological activity index (HAI) grade and the presence or absence of MAdCAM-1 expression. CONCLUSION: MAdCAM-1 expression may be important in the recruitment of lymphocytes to the liver during inflammation.

Animals↗
PubMed1982

The ontogeny of immunological receptors in the thymus.

Receptors for sheep erythrocytes, for the Fc part of IgG (Fc gamma R) and IgM (Fc mu R), and for components of activated human complement C3 (C3bR and C3dR) in thymus tissue from fetuses, infants and children were studied using haemadsorption to cryostat sections in a closed chamber. Sheep erythrocytes (SE) did not adhere to sections of thymus from fetuses at 10-11 weeks of gestation, adhered weakly between 14 and 20 weeks, while they adhered in a dense monolayer in older fetuses, in infants and in children, denser in the cortex than in the medulla. Ox erythrocytes (OE), sensitized with IgG to demonstrate Fc gamma R, adhered focally to both cortical and medullary areas. The adherence was more pronounced to the sections of fetal thymus than to the sections from infants and children. OE, sensitized with IgM to demonstrate Fc mu R, adhered focally to all thymus tissue sections, preferentially to the cortex. The adherence was most pronounced in fetal thymus. SE, sensitized with IgM and coated with complement, adhered to sections of fetal thymus, but the density decreased markedly during fetal life. Indicator cells demonstrating C3bR adhered focally also to sections from infants and children, while indicator cells demonstrating C3dR did not adhere to sections from individuals older than 38 weeks of gestation. Indicator cells demonstrating C3bR and C3dR adhered both to cortex and medulla.

Animals↗
PubMed1993

Inhibition of an in vivo antigen-specific IgE response by antibodies to CD23.

Immunoglobulin E (IgE) mediates many allergic responses. CD23 is a 45-kilodalton type II transmembrane glycoprotein expressed in many cell types. It is a low-affinity IgE receptor and interacts specifically with CD21, thereby modulating IgE production by B lymphocytes in vitro. In an in vivo model of an allergen-specific IgE response, administration of a rabbit polyclonal antibody to recombinant human truncated CD23 resulted in up to 90 percent inhibition of ovalbumin-specific IgE synthesis. Both Fabs and intact IgG inhibited IgE production in vitro and in vivo. Thus, CD23 participates in the regulation of IgE synthesis in vivo and so could be important in allergic disease.

Amino Acid Sequence↗
PubMed2005

Essential role for humoral immunity during Ehrlichia infection in immunocompetent mice.

Although cellular immunity is essential for host defense during intracellular bacterial infections, humoral immunity can also play a significant role in host defense during infection by some intracellular bacteria, including the ehrlichiae. Antibodies can protect susceptible SCID mice from fatal Ehrlichia chaffeensis infection, an observation that has been hypothesized to involve the opsonization of bacteria released from host cells. To determine whether humoral immunity plays an essential role during ehrlichia infection in immunocompetent mice, we utilized a murine model of fatal monocytotropic ehrlichiosis caused by Ixodes ovatus ehrlichia. Mice lacking either B cells or FcgammaRI were unable to resolve a low-dose (sublethal) I. ovatus ehrlichia infection, which suggested that humoral immunity is essential for resistance. Polyclonal sera generated in I. ovatus ehrlichia-infected mice recognized a conserved ehrlichia outer membrane protein and, when administered to infected mice, caused a significant decrease in bacterial infection. Mice experimentally depleted of complement, or deficient for complement receptors 1 and 2, were also susceptible to sublethal I. ovatus ehrlichia infection, as were mice that lacked the phox91 subunit of NADPH oxidase. The data are consistent with a mechanism whereby bacteria released from infected cells are lysed directly by complement or undergo antibody-mediated FcgammaR-dependent phagocytosis and subsequent exposure to reactive oxygen intermediates. The findings suggest mechanisms whereby antibodies contribute to immunity against intracellular bacteria in immunocompetent mice.

Animals↗
PubMed1983

Sendai virus envelopes can mediate Epstein-Barr virus binding to and penetration into Epstein-Barr virus receptor-negative cells.

Epstein-Barr virus (EBV) receptor-negative cells were treated with UV-inactivated Sendai virus (SV) or with reconstituted SV envelopes having a low hemolytic activity and then assayed for EBV binding or for susceptibility to EBV infection. EBV binding was assessed by using both unlabeled and fluoresceinated EBV preparations. It was found that SV or SV envelope treatment renders these cells able to bind EBV. Various experiments were performed to clarify the mechanism of this SV-induced binding. The EBV receptor-negative 1301 cells were treated with SV either at 0 degrees C or at both 0 and 37 degrees C successively and then examined for EBV binding at 0 degrees C. It was thus found that when SV treatment was performed exclusively at 0 degrees C, the target cells showed higher fluorescence intensity after their incubation with fluoresceinated EBV. In addition, Clostridium perfringens neuraminidase treatment of 1301 cells did not induce any EBV binding to these cells. These data indicate that EBV binding is not due to the disturbance of the cell membrane by SV envelope fusion or to the uncovering of EBV binding sites on the cells after the enzymatic action of SV neuraminidase. Moreover, bound EBV was partly eluted from SV-treated 1301 cells at 37 degrees C, and the treatment of EBV with C. perfringens neuraminidase inhibited its SV-mediated binding. These data indicate that EBV binds to the hemagglutinin-neuraminidase of SV on the target cell surface and that a fraction of the bound EBV becomes irreversibly associated with the SV-treated cell membrane. Our data also show that EBV can penetrate into 1301 cells which have incorporated SV envelopes into their membrane, as demonstrated by the induction of the EBV-determined nuclear antigen by B95-8 EBV in SV envelope-treated 1301 cells.

Animals↗
PubMed1985

Identification and characterization of the Epstein-Barr virus receptor on human B lymphocytes and its relationship to the C3d complement receptor (CR2).

In pursuing studies on the early events in the infection of human B cells by Epstein-Barr virus (EBV), we examined the host cell attachment phase with a panel of B-cell-specific monoclonal antibodies. One of the monoclonal antibodies, OKB7, directly blocked the attachment of purified EBV to B lymphocytes in the absence of a second anti-immunoglobulin antibody and thereby prevented EBV infection of tonsil and peripheral blood B cells. Although earlier studies have shown a close association of the EBV and complement receptor (CR2), an anti-CR2 monoclonal antibody, anti-B2, did not directly block the binding of EBV to B cells. A comparison of the structures recognized by these monoclonal antibodies on various cell types and their functional and physiochemical properties was undertaken. Flow cytometric analysis revealed that the molecules detected by OKB7 and anti-B2 were coexpressed to the same extent on B cells but were not expressed on T-cell lines. OKB7 and anti-B2 both immunoprecipitated a 145,000-molecular-weight membrane protein with an isoelectric point of 8.2 from membrane extracts of Raji lymphoblastoid cells. OKB7 and, to a lesser extent, anti-B2 directly blocked the attachment of C3d,g-coated fluorescent microspheres and sheep erythrocytes bearing C3d to B cells, indicating that these antibodies also react with CR2. These studies indicate that the EBV-CR2 receptor is a single membrane glycoprotein which possesses multiple antigenic and functional epitopes.

Antibodies, Monoclonal↗
PubMed1986

Purification of the Epstein-Barr virus/C3d complement receptor of human B lymphocytes: antigenic and functional properties of the purified protein.

The Epstein-Barr virus/C3d receptor (CR2) of human B lymphocytes was purified to homogeneity from Raji cells by immunoaffinity chromatography. The average yield of the 145-kilodalton receptor was 400 pmol (50 micrograms) per 10(10) cells, representing an approximate 75% recovery. The isolated 145-kilodalton protein was antigenically and functionally intact as it reacted with several anti-CR2 monoclonal antibodies and bound purified Epstein-Barr virus and C3d,g. These findings with the purified molecule provide an unequivocal demonstration of the dual receptor functions of this protein.

B-Lymphocytes↗