bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of murine B1 lymphocytes by interleukin‐12
Authors: Vogel Laura A. , Lester Terry L. , Van Cleave Victor H. , Metzger Dennis W. 
Published: March 2007

AbstractB1 cells are a subset of B lymphocytes found in many spectes and are implicated in the development of autoimmunity. B1 cells have previously been shown to be suppressed by the T helper (Th)1 cytokine interferon (IFN)‐γ, and to be stimulated by the Th2 cytokines interleukin (IL)‐2, IL‐4, IL‐5 and IL‐10. To examine further the interactions of B1 cells and Th1 cells, we have now tested the effects of the Th1 cell‐inducing cytokine IL‐12 on murine B1 cells. BALB/c mice were immunized with phosphorylcholine conjugated to keyhole limpet hemocyanin (PC‐KLH) and simultaneously treated with 1 μg recombinant murine IL‐12 for 3 consecutive days. In addition to altering the isotype and idiotype distribution of anti‐PC antibodies, IL‐12 treatment was found to cause a loss of peritoneal, but not splenic B lymphocytes in immunized mice. B cell depletion required exposure to IL‐12 plus antigenic stimulation. Levels of peritoneal B lymphocytes were fully restored by day 45, but the majority of these cells belonged to the B2 subset. Additionally, proliferation of B1 cells in vitro induced by IL‐5 was substantially inhibited by IL‐12. IL‐12 itself had no effect on viable cell recovery of peritoneal cells (PeC) cultured in vitro, but viable cell recovery was significantly decreased in PeC cultured with IL‐5 plus IL‐12. These results show that IL‐12 causes the loss of murine peritoneal B1 cells and suggest that treatment with this cytokine may be useful for disease conditions that involve B1 cell dysfunction.
Interleukin‐2 receptor common γ‐chain signaling cytokines regulate activated T cell apoptosis in response to growth factor withdrawal: Selective induction of anti‐apoptotic (bcl‐2, bcl‐xL) but not pro‐apoptotic (bax, bcl‐xS) gene expression
Authors: Akbar Arne N. , Borthwick Nicola J. , Wickremasinghe R. Gitendra , Panayiotidis Panayiotis , Pilling Darrell , Bofill Margarita , Krajewski Stanislaw , Reed John C. , Salmon Mike 
Published: March 2007

AbstractCytokine deprivation from activated T cells leads to apoptosis associated with down‐regulation of the bcl‐2 gene product. It is not clear, however, how cytokines other than interleukin‐2 (IL‐2) may affect this process and regulate the involvement of other apoptosis‐modulating genes. We show that a group of cytokines including IL‐2, IL‐4, IL‐7 and IL‐15, which can all signal through the γ chain of the IL‐2R (IL‐2Rγ), prevent the apoptosis of IL‐2‐deprived activated T cells. This rescue involves the induction of the anti‐apoptosis genes (bcl‐2 and bcl‐xL), but causes little change in expression of bax and bcl‐xS, which promote apoptosis. Furthermore, the prevention of apoptosis and induction of proliferation by the common γ chain cytokines can be dissociated. Thus, when proliferation is blocked, the common γ chain cytokines still induce up‐regulation of bcl‐2 relative to bax and retard apoptosis. These cytokines can thus regulate the persistence or removal of effector T cells by coordinating the balance between genes which promote and those which inhibit apoptosis, events which are probably mediated at least in part by signals through the common γ chain. These data also implicate inappropriate T cell apoptosis resulting from a dysfunctional common γ‐chain as part of the pathophysiological defect in patients with X‐linked severe‐combined immunodeficiency (SCID).
B7‐1 synergizes with interleukin‐12 in interleukin‐2 receptor α expression by mouse T helper 1 clones
Authors: Igarashi Osamu , Yanagida Tetsuya , Azuma Miyuki , Okumura Ko , Nariuchi Hideo 
Published: March 2007

AbstractExpression of interleukin‐2 receptor α (IL‐2Rα) is critical to induce interleukin (IL)‐2‐dependent proliferation of T helper (Th)1 clones. The IL‐2Rα expression of Th1 clones is known to be up‐regulated by IL‐12. Co‐stimulation via CD28/CTLA‐4 is also known to be important for efficient activation of CD4+ T cells. In the present experiments, IL‐12‐induced enhancement of IL‐2Rα expression of Th1 clones stimulated with B cells as antigen‐presenting cells (APC) is suppressed by the addition of anti‐B7‐1. To analyze the mechanism, Th1 clones were stimulated with immobilized anti‐CD3 plus IL‐12 in the presence or absence of chinese hamster ovary cells that express mouse B7‐1 (B7‐1CHO) and the enhancement of IL‐2Rα expression induced by the co‐stimulation was analyzed. The results of these experiments indicate that B7‐1 synergizes with IL‐12 in IL‐2Rα expression of the Th1 clone stimulated with anti‐CD3, although B7‐1CHO alone did not enhance IL‐2Rα expression of the clones. B7‐1 stimulation is not mediated by the enhancement of IL‐2 production: B7‐1 enhancement of IL‐2Rα expression was FK506 resistant, while the inclusion of FK506 abrogated IL‐2 production of the Th1 cells. B7‐1 co‐stimulation did not stabilize IL‐2Rα mRNA, but did synergize with IL‐12 to enhance IL‐2Rα mRNA transcription.
Neonatally tolerant rats actively eliminate donor‐specific lymphocytes despite persistent chimerism
Authors: Cutler Antony J. , Bell Eric B. 
Published: March 2007

AbstractRats from the allotype‐marked PVG‐RT7b and PVG‐RT1u‐RT7b strains were injected at birth with semi‐allogeneic F1 bone marrow (BM) cells from athymic nude rats (PVG‐rnu/rnu x PVG‐RT1u‐rnu/rnu) to induce neonatal tolerance. As adults, 97% of the animals accepted donor‐specific allogeneic skin grafts and a majority (65%) of rats were chimeric, expressing the major histocompatibility complex class I and allotype marker of the donor strain. Similar results were obtained when PVG‐RT1u‐RT7b rats were injected at birth with fully allogeneic PVG‐rnu/rnu nude BM cells: as adults, 94% accepted donor‐specific skin allografts and 76% of recipients were chimeric. Donor‐derived CD4T cells, CD8T cells and B cells were found in low numbers (< 2%) in peripheral blood of rats made tolerant by F1 BM cells. A large proportion of T cells bore the phenotype of recent thymic emigrants, suggesting that they were newly produced. All the evidence was consistent with clonal deletion tolerance, induced centrally within the thymus. The thymus was chimeric and thymocytes failed to respond in vitro to alloantigens of the donor‐specific haplotype; donor‐specific skin allografts survived indefinitely on athymic nude recipients reconstituted with CD4+CD8− thymocytes or peripheral CD4T cells from tolerant animals. The chimeric state was interesting, since the PVG and PVG‐RT1u rat strains contain a natural killer (NK) cell system that rapidly eliminates (within 24 h) intravenously injected allogeneic or semi‐allogeneic lymphocytes – a phenomenon known as allogeneic lymphocyte cytotoxicity or ALC. When neonatal tolerant rats were tested, the ALC index (a measure of cell killing) was unchanged in nonchimeric tolerant rats and significantly altered (reduced killing), but not abolished in chimeric animals. Hence, the injection of allogeneic BM cells which induced specific tolerance in the T cell population failed to tolerize the NK cell system, allowing the constant killing of newly produced donor‐derived lymphocytes and putting at risk the very survival of the allogeneic BM cells. This has interesting implications for clinical transplantation.
An HLA‐B35‐restricted epitope modified at an anchor residue results in an antagonist peptide
Authors: Dong Tao , Boyd Diana , Rosenberg William , Alp Nick , Takiguchi Masafumi , McMichael Andrew , Rowland‐Jones Sarah 
Published: March 2007

AbstractPeptides associated with HLA‐B35 commonly have a proline or occasionally a serine residue in the P2 anchor position of the peptide, with a tyrosine at the C terminus. Based on this motif, we identified an octamer epitope from influenza A matrix protein which is presented by HLA‐B35. The requirements for MHC binding and T cell receptor contact have been analyzed using analogs of this peptide with substitutions at positions 1, 2, 4, 7 and 8. The natural epitope contains a serine residue at P2 of the peptide. Substitution of this residue with proline (the favored amino acid in this position in B35‐associated peptides) considerably enhances binding to HLA‐B35 in the T2‐B35 cell line, but the peptide is not recognized by the majority of CTL clones and can antagonize recognition of the index peptide. This suggests that a conservative substitution at the P2 anchor position results in a conformational change in the peptide‐MHC surface exposed to the T cell receptor.
IgD‐receptor up‐regulation on human peripheral blood T cells in response to IgD in vitro or antigen in vivo correlates with the antibody response to influenza vaccination
Authors: Swenson Christina D. , Cherniack E. Paul , Russo Carlo , Thorbecke G. Jeanette 
Published: March 2007

AbstractAged individuals (>65 years) were classified as antibody (Ab) responders on the basis that they showed increases to ⩾1:40 in serum Ab titers to all influenza virus strains present in the trivalent influenza vaccine within 4 weeks after immunization. The peripheral blood mononuclear cells (PBMC) from pre‐immunization samples of blood taken from seven Ab‐responders and seven Ab‐nonresponders were examined for their ability to exhibit up‐regulation of IgD‐receptor (IgD‐R) after exposure for 2 h to immobilized cross‐linked IgD, as shown by rosetting with IgD‐coated ox erythrocytes. The responsiveness to IgD was found to be predictive of the ability to produce Ab responses to viral protein Ag: the IgD‐R up‐regulation was > 5% in all Ab‐responders and < 4% in all the Ab‐nonresponders. In addition, there was an excellent correlation between mean Ab titers (to the three viruses in sera collected 4 weeks after immunization) and the percentage of IgD‐R+ cells obtained in response to IgD in PBMC from the same individual prior to immunization: p = 0.894.Injection of influenza vaccine itself also induced IgD‐R on PBMC in vivo. The percentage of IgD‐R+ cells peaked after 24 h, was still detectable above background by day 7 or 14, and returned to pre‐injection levels by day 28 in young subjects and aged Ab‐responders, but not in Ab‐nonresponders. Similarly, purified peripheral blood T cells obtained from aged Ab‐responders exhibited IgD‐R upon immunization in vivo. These findings suggest that Ag injection causes rapid up‐regulation of IgD‐R by cross‐linking IgD in humans as well as in mice as shown previously. In analogy with results in mice, the present data are consistent with a role for IgD‐R+ T cells in the humoral response in man. Proliferative responses to influenza proteins in peripheral blood T cells from vaccinated individuals were found to peak on day 7 and were higher in Ab‐responders than in Ab‐nonresponders.
Interleukin‐6 induces tyrosine phosphorylation of the Ras activating protein Shc, and its complex formation with Grb2 in the human multiple myeloma cell line LP‐1
Authors: Neumann Carola , Zehentmaier Gundula , Danhauser‐Riedl Susanne , Emmerich Bertold , Hallek Michael 
Published: March 2007

AbstractLike many other cytokines and growth factors, interleukin‐6 (IL‐6) activates p21ras. However, the precise biochemical mechanisms inducing this activation are unknown. Therefore, we investigated the effects of IL‐6 on some recently identified signaling intermediates, Shc (Src homology and collagen) and Grb2 (growth factor receptor bound protein 2), known to activate p21ras. In the multiple myeloma cell line LP‐1, IL‐6 stimulated the tyrosine phosphorylation of Shc in a time‐ and concentration‐dependent manner. This led to the complex formation of Shc with Grb2, an adaptor protein known to relocate a p21ras‐GDP exchange factor, Sos1 (Son‐of‐sevenless), to the cell membrane. Taken together, these findings suggest that IL‐6 might activate the Ras signaling pathway via tyrosine phosphorylation of Shc and subsequent recruitment of Grb2. Further studies will elucidate which of the IL‐6 receptor associated non‐receptor tyrosine kinases of the Src kinase or Janus kinase family, mediate these effects.
Expression of a mannose/fucose membrane lectin on human dendritic cells
Authors: Avraméas Alexandre , McIlroy Dorian , Hosmalin Anne , Autran Brigitte , Debré Patrice , Monsigny Michel , Roche Annie Claude , Midoux Patrick 
Published: March 2007

AbstractDendritic cells (DC) are the most efficient antigen presenting cells for T lymphocytes. CD1a+ CD14− DC with high antigen‐presenting capacities can now be obtained easily from adherent peripheral blood monocytes by culture in the presence of granulocyte/macrophage colony‐stimulating factor and interleukin‐4 (Sallusto et al., J. Exp. Med. 1994. 179: 1109). Human macrophages express a membrane lectin, or sugar‐specific receptor, which specifically mediates the binding and endocytosis of mannose‐ and fucose‐terminated glycoproteins and is involved in the phagocytosis of pathogens. A similar lectin activity was sought on cultured human DC using flow cytometry and confocal microscopy to detect binding and internalization of fluoresceinated neoglycoproteins [bovine serum albumin (BSA) substituted with sugar residues]. Several neoglycoproteins, especially α‐L‐fucosyl‐, α‐D‐mannosyl‐, N,N′‐di‐acetyl‐β‐chitobiosyl‐ and β‐D‐glucosyl‐BSA, were endocytosed by cultured human CD1a+ DC as well as by CD1a− CD14− cells which were also obtained in the culture. Fuc‐BSA and Man‐BSA had the same number of binding sites (1.7 × 106/cell) on CD1a+ DC, and bound with an affinity constant close to 107 l/mol. Inhibition experiments indicated that these two neoglycoproteins bound to the same membrane lectin. CD1a+ and CD1a− cells were both labeled by an antiserum specific for the human macrophage mannose receptor. The membrane lectin specific for mannose and fucose that is evidenced in these experiments on cultured DC may be similar to the macrophage membrane lectin or may share functional and structural properties with it.
Inhibition of I‐Ad‐, but not Db‐restricted peptide‐induced thymic apoptosis by glucocorticoid receptor antagonist RU486 in T cell receptor transgenic mice
Authors: Xue Yintong , Murdjeva Marianna , Okret Sam , McConkey David , Kiuossis Dimitris , Jondal Mikael 
Published: March 2007

AbstractThymocytes differentiate by positive and negative selection of immature CD4+CD8+T cells. Negative selection occurs by default or by high‐affinity recognition of peptides bound to proteins encoded by the major histocompatibility complex (MHC). MHC class I molecules are expressed on many different cell types, although at different levels, whereas MHC class II molecules are selectively expressed on thymic epithelial cells (TEC) and dendritic cells (DC). We investigated the role of the glucocorticoid receptor (GR) in thymic negative selection using the receptor antagonist RU486. Glucocorticoids (GC) are known to be potent inducers of apoptosis in CD4+CD8+thymocytes, and we have earlier shown that anti‐CD3‐induced thymic apoptosis can be blocked by RU486in vivo.We now show that anti‐CD3 induces thymic apoptosis in mice that have been adrenalectomized (ADX), and that RU486 inhibits anti‐CD3 antibody‐mediated thymocyte killing in newborn thymic organ cultures. Thymocyte apoptosis induced by ovalbumin peptide OVA323–339 treatment of mice transgenic for the DO11.10T cell receptor (TCR), which recognizes this peptide in the context of I‐Ad, was found to be inhibited by RU486. These mice responded to peptide treatment by an extensive activation of the peripheral immune system, which became lethal in 60% of the mice when accompanied by simultaneous RU486 treatment. In contrast, RU486 had no effect on thymic apoptosis induced by the influenza A nucleoprotein NP366–374 peptide, recognized in context of Db, in F5 TCR transgenic mice. We interpret the results to demonstrate that different deletion systems operate in the thymus. We propose that endogenous GC may be important for negative selection by default and by high‐affinity recognition of endogenous MHC‐presented peptides on TEC.
Binding of nucleosomes to a cell surface receptor: Redistribution and endocytosis in the presence of lupus antibodies
Authors: Kontouzov Sophie , Cabrespines Alban , Amoura Zahir , Chabre Henri , Lotton Chantal , Bach Jean‐François 
Published: March 2007

AbstractIn the present study, we sought evidence for a surface nucleosome receptor in the fibroblastic cell line CV‐1, and questioned whether anti‐double‐stranded (ds)DNA and/or anti‐histone autoantibodies could recognized and influence the fate of cell surface‐bound nucleosomes. 125I‐labeled mononucleosomes were shown to bind to the cell layer in a specific, concentration‐dependent and a saturable manner. Scatchard analysis revealed the presence of two binding sites: a high‐affinity site with a Kd of ∼ 7nM and a low‐affinity site (Kd ∼ 400 nM) with a high capacity of 9 × 107 sites. Visualization of bound mononucleosomes by fluorescence revealed staining on both the cell surface and the extracellular matrix (ECM). Purified mononucleosome‐derived dsDNA (180–200 bp) was found to compete for binding of 125I‐mononucleosomes on the low‐affinity site, to stain exclusively the ECM in immunofluorescence, and to precipitate three specific proteins of 43, 180 and 240 kDa from 125‐I‐labeled cell lysates. Nucleosomes were found to precipitate not only the 180‐kDa dsDNA‐reactive component, but also a unique protein of 50 kDa, suggesting that this protein is a cell surface receptor for nucleosomes on these fibroblasts. Once bound on the cell surface, mononucleosomes were recognized and secondarily complexed by lupus anti‐dsDNA or anti‐histone antibodies (i.e. anti‐nucleosome antibodies), thus forming immune complexes in situ. The presence of these complexing auto‐antibodies was found dramatically to enhance the kinetics of mononucleosome internalization. Following the internalization of the nucleosome‐anti‐nucleosome complexes by immunofluorescence, we observed the formation of vesicles at the edge of the cells by 5–10 min which moved toward the perinuclear region by 20–30 min. By means of double‐fluorescence labeling and proteolytic treatment, these fluorescent vesicles were shown to be in the cytoplasm, suggesting true endocytosis of nucleosome‐anti‐nucleosome immune complexes. As shown by confocal microscopy, at no stage of this endocytic process was there any indication that coated pits or coated vesicles participated. Co‐distribution of the endocytic vesicles with regions rich in actin filaments and inhibition of endocytosis of nucleosome‐anti‐nucleosome complexes by disruption of the micro‐filament network with cytochalasin D suggest a mechanism mediated by the cytoskeleton. Taken together, our data provide evidence for the presence of a surface nucleosome receptor. We also show that anti‐dsDNA and anti‐histone antibodies can form nucleosome‐anti‐nucleosome immune complexes in situ at the cell surface, and thus dramatically enhance the kinetics of nucleosome endocytosis.
Identification and characterization of a human CD4 silencer
Authors: Donda Alena , Schulz Manfred , Bürki Kurt , De Libero Gennaro , Uematsu Yasushi 
Published: March 2007

AbstractUsing transgenic mice, we have identified a human CD4 silencer contained within a 484‐bp fragment in the first intron of the CD4 gene. Further experiments have mapped a lineage‐specific silencing activity to a region of 190 bp. This region contains two protein‐binding sites detected by deoxyribonuclease I footprinting analyses. Tested in transient transfection assays, these two DNA elements showed significant silencing activity restricted to the CD8 phenotype. In CD4 cells, either no clear effect (FP I) or strong enhancing activity (FP II) was observed by transient transfection assays. Despite the lineage‐specific activity of these two elements, electrophoretic mobility shift assays (EMSA) showed similar levels of protein binding to the silencer element FP I in CD4 and CD8 T cells. Base substitutions in the FP I fragment abolished the silencing activity in transfected CD8 cells as well as the protein binding in EMSA, suggesting an important role of this protein‐DNA interaction in CD4 gene regulation.
Nitric oxide synthase: expression of the endothelial, Ca2+/calmodulin‐dependent isoform in human B and T lymphocytes
Authors: Reiling Norbert , Kröncke Rolf , Ulmer Artur J. , Gerdes Johannes , Flad Hans‐Dieter , Hauschildt Sunna 
Published: March 2007

AbstractNitric oxide (NO) is a pleiotropic mediator of a variety of cellular processes such as vasorelaxation, neurotransmission, and cytotoxicity. We studied the expression of the human endothelial, Ca2+/calmodulin‐dependent NO synthase (NOS) isoform (ecNOS) in highly purified human lymphocytes from peripheral blood and tonsillar tissue. ecNOS mRNA was detected in IgD+ or IgD− B cells, peripheral blood and tonsillar T cells. Upon stimulation, ecNOS mRNA expression decreased in all these lymphocyte subpopulations. Germinal center T cells and follicular dendritic cells did not express ecNOS mRNA either in an unstimulated or in a stimulated state. ecNOS expression by human lymphocytes was further substantiated by its mRNA detection in lymphoid cell lines such as Raji, Daudi, and Jurkat. By the use of a specific monoclonal antibody, ecNOS was shown to be present in T cells from peripheral blood and in various germinal center cells of frozen tonsillar sections. These data are the first to demonstrate the expression of the endothelial ecNOS at mRNA and protein level in human lymphocytes.
A functional analysis of recombinant soluble CD46 in vivo and a comparison with recombinant soluble forms of CD55 and CD35 in vitro
Authors: Christiansen Dale , Milland Julie , Thorley Bruce R. , McKenzie Ian F. C. , Loveland Bruce E. 
Published: March 2007

AbstractThe human cell surface complement regulatory proteins CD46 (MCP), CD55 (DAF) and CD35 (CR1) protect autologous cells from complement‐mediated damage by inhibiting C3 and C5 convertases. This regulatory potential has previously been exploited in the treatment of some models of inflammatory injury by the generation of recombinant soluble (rs) proteins, such as rsCD55 and rsCD35. More recently, we have shown that rsCD46 inhibits complement activation in the fluid phase. In this report, the ability of rsCD46, rsCD55 and rsCD35 to regulate human complement activation mediated by the classical and alternative pathways was directly compared. Regulation of the classical pathway in vitro was clearly demonstrated by all three soluble proteins; however, rsCD35 was a more effective inhibitor than either rsCD46 or rsCD55. A combination of rsCD46 + rsCD55 was more potent than either of these proteins alone. Cell lysis via alternative pathway activation in vitro was efficiently regulated by rsCD46 and rsCD35 to a similar extent, whereas rsCD55 was not as effective. Assays of rsCD46 in vivo have previously not been possible due to difficulties in expressing sufficient quantities of protein. This limitation has been overcome and now we report the ability of rsCD46 to inhibit immune complex‐mediated inflammation in a rat using the reverse passive Arthus reaction model. Administration of rsCD46 significantly reduced the size of lesion, and histological examination showed a reduction in inflammatory infiltrate and edema. These data suggest that rsCD46, in addition to rsCD55 and rsCD35, may be a useful therapeutic agent.