bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of mouse CD53: Epitope mapping, cellular distribution and induction by T cell receptor engagement during repertoire selection
Authors: Tomlinson Michael G. , Hanke Thomas , Hughes Derralyn A. , Barclay A. Neil , Scholl Eva , Hünig Thomas , Wright Mark D. 
Published: March 2007

AbstractThe pan‐leukocyte antigen CD53 is a member of the poorly understood transmembrane 4 superfamily (TM4SF) of cell membrane glycoproteins. CD53 is proposed to play a role in thymopoiesis, since rat CD53 is expressed on immature CD4−8−thymocytes and the functionally mature single‐positive subset, but is largely absent from the intermediate CD4+8+ cells. We have characterized CD53 in the mouse through the production of two new monoclonal antibodies, MRC OX‐79 and OX‐80, which were raised against the RAW 264 cell line and screened on recombinant CD53 fusion proteins. The epitopes recognized by both antibodies are dependent on disulfide bonding and map to the major extracellular region of CD53, requiring the presence of a single threonine residue at position 154. Mouse CD53 has a molecular mass of 35‐45 kDa and is expressed on virtually all peripheral leukocytes, but not on cells outside the lymphoid or myeloid lineages. CD53 expression distinguishes subpopulations of thymocytes in the mouse and resembles the expression pattern of rat CD53. Amongst the immature CD4−8− thymocytes, mouse CD53 is clearly detectable on the earliest CD44high25− subset, but down‐regulated on the later CD44high25+, CD44low25+ and CD44low25− stages. Also, the subsequent transient TcR−/low CD4−8+ cells and most CD4+8+ thymocytes express little or no CD53. This is consistent with the idea that cells which are committed to enter the selectable CD4+8+ compartment switch off CD53. The effect of T cell receptor (TcR) engagement on the reexpression of CD53 on CD4+8+ thymocytes was studied both ex vivo and in vitro using F5 mice, transgenic for the H‐2b/influenza nucleoprotein‐peptide‐specific TcR, back‐crossed onto an H‐2q or H‐2b background of RAG‐2‐deficient mice. CD4+8+ thymocytes from non‐selecting H‐2q F5 mice are CD53 negative, but in vitro stimulation through the TcR dramatically induces CD53 expression. In contrast, a fraction of CD4+8+ thymocytes from positively selecting H‐2b F5 transgenic mice express CD53. Therefore TcR engagement by selecting major histo‐compatibility complex peptide complexes, or surrogate ligands, induces CD53 expression on otherwise CD53‐negative, non‐selected CD4+8+ thymocytes. Whether CD53 itself participates as a signaling molecule in further stages of thymic selection is still a matter of speculation.
Regulation of the function of the first component of complement by human C1q receptor
Authors: van den Berg Rocco H. , Faber‐Krol Maria , van Es Leendert A. , Daha Mohamed R. 
Published: March 2007

AbstractA membrane‐associated receptor for the C1q subcomponent of complement is widely distributed among different cell types. While a number of possible physiological functions of the C1q receptor (C1qR) on different cell types have been described, the way in which C1qR regulates complement activity remains unclear. This report describes the mechanism by which C1qR regulates activation of the first component of complement, C1. Using purified components of complement, we were able to show that membrane‐associated C1qR as well as detergent‐solubilized C1qR, purified from polymorphonuclear leukocytes, human umbilical vein endothelial cells or an endothelial cell line, EA.hy 926, are able to inhibit complement‐mediated lysis of C1q‐sensitized erythrocytes. Using hemolytic assays, we were able to demonstrate that C1qR prevents the association of C1q with C1r and C1s to form macromolecular C1. In addition, incubation of C1qR with the collagen‐like stalks, but not with the globular heads of C1q, inhibits the effect of C1qR. This demonstrates that C1qR exerts its complement inhibitory effect by binding to the collagen‐like stalk of C1q. No complement regulatory effect of C1qR was observed on preformed macromolecular C1. These data suggest that besides such well‐known complement regulatory molecules as CD55 (DAF), CD46 (MCP), CD35 (CR1) and CD59 (HRF), C1qR too is able to regulate complement activity.
Compounds that induce autoimmunity in the Brown Norway rat sensitize mast cells for mediator release and interleukin‐4 expression
Authors: Oliveira David B. G. , Gillespie Kathleen , Wolfreys Karen , Mathieson Peter W. , Qasim Faieza , Coleman John W. 
Published: March 2007

AbstractBrown Norway (BN) rats given mercuric chloride (HgCl2), gold (Au) salts or D‐penicillamine develop a T helper 2 (Th2) cell‐mediated autoimmune syndrome. The recent observation of tissue injury within 24 h of HgCl2 treatment suggested the involvement of a non‐T cell. We therefore examined the effect of these compounds on rat mast cells in vitro. Incubation of BN rat peritoneal mast cells with HgCl2 enhanced the release of serotonin in response to IgE cross‐linking agents. Mast cells from Lewis rats, a strain not susceptible to the autoimmune syndrome in vivo, were affected to a lesser extent. The effect was observed with purified BN mast cells, suggesting a direct action. Similar effects were seen with D‐penicillamine in the presence of copper ions, a combination that produces hydrogen peroxide, and Au. HgCl2 caused significant induction of interleukin (IL)‐4 mRNA in mast cells from BN, but not Lewis rats. The data demonstrate a novel enhancing effect of a number of compounds on mast cell mediator release, and an inducing effect of HgCl2 on mast cell IL‐4 expression. These findings are consistent with our hypotheses that mast cells may contribute to early tissue injury, and also, via production of IL‐4, may initiate and/or augment, the Th2 response in the BN rat model of chemical‐induced autoimmunity.
The effect of carrier and carrier priming on the kinetics and pattern of somatic mutation in the VϰOx1 gene
Authors: Källberg Eva , Gray David , Leanderson Tomas 
Published: March 2007

AbstractPriming mice with a chicken gamma globulin (CGG) carrier protein significantly accelerated the onset of somatic mutation in the VϰOx1 gene when the mice were subsequently immunized with 2‐phenyl‐5‐oxazolone (phOx) coupled to CGG. The first mutations were already detected 7 days after immunization, while in the true primary response, they are not apparent until day 10. It was also found that comparing the mutation pattern of VϰOx1 genes from hybridomas derived after immunization with phOx coupled to different carriers revealed quite distinct patterns of somatic mutation. Analysis of hybridoma sequences from the primary immune response to phOx‐ovalbumin showed that the codons for Ser29, Ser31 and Lys45 were hot‐spots for somatic mutation. Thus, the frequency and pattern of somatic mutations in the VϰOx1 gene depends on the available T cell help as well as on the complex structure of the immunizing antigen.
Modulation of peptide binding by HLA‐B27 polymorphism in pockets A and B, and peptide specificity of B*2703
Authors: Villadangos José A. , Galocha Begoña , García Fernando , Albar Juan P. , de Castro José A. López 
Published: March 2007

AbstractThe results in this study address three aspects of peptide binding to the disease‐associated antigen HLA‐B27 and its modulation by polymorphism: the contribution of major anchor residues 2 and 9, the role of pocket B polymorphism in modulating peptide specificity, and the binding properties of B*2703, a subtype not found to be associated with spondyloarthropathy. Synthetic analogs of peptides naturally presented by B*2705 were used to demonstrate that residue 2 is essential, since Ala2 analogs bound marginally to B*2705, but the specificity of B*2705 for Arg2 is not absolute, and show that the contribution of basic residue 9 to binding was significant, but less than Arg2. The effect of single mutations in the B pocket was to decrease or ‐ with the Glu > Met‐45 mutation ‐ totally shift pocket B specificity for Arg2 towards other residues at this position. This was shown by quantitating the relative binding of Gln2 and Ala2 analogs, and by pool‐sequencing of the peptides bound in vivo to these mutants. Peptides naturally presented by B*2705 apparently bound with a lower affinity to pocket A variants with altered hydrogen bonding to the peptide N terminus, including B*2703. Binding of peptide analogs with changes at positions 2 or 9 suggested that in B*2703 pocket A, interactions are weaker and pocket B interactions are stronger than in B*2705. This can be explained by the effect of the unique His59 change in B*2703 in both pockets. Thus, B*2703 is probably the HLA‐B27 subtype with the most stringent specificity for the Arg2 peptide motif.
Soluble interleukin‐6 receptor strongly increases the production of acute‐phase protein by hepatoma cells but exerts minimal changes on human primary hepatocytes
Authors: Gabay Cem , Silacci Paolo , Genin Bernard , Mentha Gilles , le Coultre Claude , Guerne Pierre‐André 
Published: March 2007

AbstractInterleukin‐6 (IL‐6) interacts with a system of receptors, which include a 80‐kDa IL‐6‐binding subunit (IL‐6R) and a transducing element (gp130). The soluble form of IL‐6R (sIL‐6R) can bind its ligand and induce cellular responses by association with gp130, thus acting as an IL‐6 agonist. We and others have previously shown that the responsiveness to IL‐6 is different in hepatoma and human primary hepatocytes. We therefore compared the effects of sIL‐6R on the two types of cells, and on the B9 hybridoma, another IL‐6‐sensitive cell line. Human primary hepatocytes, hepatoma cells PLC/PRF/5, and B9 cells were incubated with different concentrations of IL‐6, sIL‐6‐R, or both. The hepatocyte culture supernatants were tested for their content of acute‐phase proteins (APP). The proliferation of B9 cells was assessed by a colorimetric method. Results showed that sIL‐6R alone markedly increases the production of APP by hepatoma cells in a dose‐dependent manner, but affects only minimally primary hepatocytes and the proliferation of B9 cells. The combinations of IL‐6R and its ligand enhanced the effects of IL‐6 alone in both PLC/PRF/5 and B9 cells, but had no effect on primary hepatocytes. An immunohistochemical study indicated that the cell‐surface expression of IL‐6R was dramatically lower in hepatoma cells than in primary hepatocytes. In conclusion, our results show that the expression of IL‐6R is low in the hepatoma cell PLC/PRF/5 when compared with primary hepatocytes and that this difference can, at least partly, explain their deficient responsiveness to IL‐6. On the other hand, it appears that IL‐6R expression by primary hepatocytes is sufficient and that circulating sIL‐6R is unlikely to play a significant role in the modulation of IL‐6 effects.
Systemic immunization induces protective CD4+ and CD8+ T cell‐mediated immune responses in murine Listeria monocytogenes meningoencephalitis
Authors: Schlüter Dirk , Oprisiu Simona B. , Chahoud Soraya , Weiner Daniela , Wiestler Otmar D. , Hof Herbert , Deckert‐Schlüter Martina 
Published: March 2007

AbstractThe immune mechanisms underlying immunization‐induced protection of mice from lethal central nervous system (CNS) listeriosis were evaluated by immuno‐histochemistry, flow cytometry of leukocytes isolated from the brain, reverse transcription‐polymerase chain reaction analysis of intracerebral (i.c.) tumor‐necrosis factor‐α, interferon‐γ, interleukin (IL)‐2, IL‐1β, IL‐10, granulocyte/macrophage colony‐stimulating factor, and inducible nitric oxide synthase mRNA expression, and T cell depletion experiments. The data demonstrate that active immunization of mice prior to an i.c. infection with Listeria monocytogenes prevents the development of a fatal necrotizing encephalitis and accelerates the recruitment of an increased number of αβ T cell receptor (TcR)+ CD4+ and CD8+ T cells, γδ TcR+ T cells, B cells, granulocytes and macrophages to the brain compared to non‐immunized animals. In addition, immunization induced a pronounced activation of i.c. macrophages and microglial cells as shown by an increased expression of MHC class II antigens. In parallel, transcript levels for all cytokine mRNA analyzed were higher in the brains of immunized mice. The protective effects of immunization were completely abolished by depletion of CD4+, CD8+, or both T cell subsets. All groups of T cell‐depleted immunized mice developed a fatal necrotizing encephalitis with an increased i.c. bacterial load. In addition, cytokine mRNA synthesis was significantly impaired. The severity of disease was only slightly different between CD4+, CD8+ and CD4+/CD8+ T cell depleted mice, indicating that both subsets of T cells are required for an effective i.c. immune response to L. monocytogenes. This is in marked contrast to systemic listeriosis, and points to CNS‐specific features of the immune response.
Interactions between the amino‐terminal domain of p56lck and cytoplasmic domains of CD4 and CD8α in yeast
Authors: Campbell Kerry S. , Buder Annie , Deuschle Ulrich 
Published: March 2007

AbstractThe interactions between CD4 or CD8 and p56lck were tested using the twohybrid protein interaction system in yeast. Plasmid constructs were created which fuse the cytoplasmic domains of either CD4 or CD8α to the DNA‐binding protein LexA, and the unique amino‐terminal domain of p56lck fused to a transcriptional activation domain. These constructs were transfected into yeast bearing lacZ and LEU2 reporter genes controlled by upstream LexA operator sequences. Yeast transfectants bearing either CD4 or CD8α hybrid proteins in combination with the amino terminal p56lck hybrid protein exhibited increased β‐galactosidase activity and growth on leucine‐deficient medium, indicating interactions between these protein domains.Quantitation of reporter activation indicated that the interaction of p56lck with CD8α is at least 18‐fold weaker than the interaction with CD4 in this assay. This reduced interactive capacity is apparently not due to competition by CD8α interacting with itself, since homotypic or heterotypic interactions between CD8α and/or CD4 could not be detected. Truncation and point mutants demonstrated that the interactions of p56lck with CD4 or CD8α were dependent on the integrity of a pair of cysteines on each protein. The results indicate that these interactions do not require any additional proteins. Additionally, expression of the entire p56lck molecule as a hybrid with LexA resulted in dramatic reduction in the growth of yeast. Though the two‐hybrid system is a powerful tool for examining protein interactions, this result indicates potential limitations in studying full‐length src family tyrosine kinases in yeast.
Interleukin‐4 and interleukin‐5 are rarely co‐expressed by human T cells
Authors: Jung Thomas , Schauer Uwe , Rieger Christian , Wagner Kathrin , Einsle Karin , Neumann Christine , Heusser Christoph 
Published: March 2007

AbstractInterleukin (IL)‐4 and IL‐5 are two cytokines which synergize in the induction of several biological effector functions. They are produced by mouse and human T helper 2 (Th2) and T helper 0 (Th0) cells. Little is known about the regulation of the two cytokines at the single‐cell level. Here we show, using a flow cytometric intracellular staining technique, that IL‐4 and IL‐5 are predominantly produced by different human peripheral CD4+ and CD8+ T cells, whereas interferon (IFN)‐γ and IL‐2 are produced by the same cells. In contrast, cloned human Th0 and Th2 cells were able to produce IL‐4 and IL‐5 simultaneously. The segregation of IL‐4 and IL‐5 in activated peripheral T cells was found within 72 h of activation upon anti‐CD3 or phorbol ester + ionomycin stimulation. The kinetics of IL‐4 and IL‐5 production were different at the mRNA and the intra‐and extracellular protein level, indicating that the cytokines are regulated differently. T cells from three patients with hyper‐IgE syndrome did not display a substantial proportion of IL‐4/IL‐5 double‐positive cells. However, simultaneous production could be induced in normal human T cells after prolonged stimulation with a minimum of two restimulation cycles. We conclude that the simultaneous production of IL‐4 and IL‐5 is a feature of repetitively activated human T cells.
Role of N‐linked glycosylation in expression of E‐selectin on human endothelial cells
Authors: Påhlsson Peter , Strindhall Jan , Srinivas Uppugunduri , Lundblad Arne 
Published: March 2007

AbstractE‐selectin is a cytokine‐inducible membrane glycoprotein capable of mediating adhesion of leukocytes to endothelial cells. It is highly glycosylated, containing 11 sites for N‐linked glycosylation. N‐Glycosylation of E‐selectin was analyzed by endoglycosidase treatment. Analysis of immunoprecipitated E‐selectin from human umbilical vein endothelial cells (HUVEC) by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate showed that E‐selectin was completely resistant to endoglycosidase H, but sensitive to peptide N‐glycanase F digestion. This suggested that all N‐linked oligosaccharide chains were of the complex type. The role of N‐linked glycosylation in surface expression and secretion of E‐selectin was studied using interleukin‐1‐stimulated HUVEC, cultured in the presence of the soluble glycosylation inhibitors tunicamycin or castanospermine. Cell surface expression was analyzed by indirect flow cytometry. N‐Glycosylation was blocked by tunicamycin, and resulted in a significantly reduced surface expression of E‐selectin, whereas castanospermine only marginally reduced E‐selectin expression. The deglycosylated forms of E‐selectin were also found to be fully capable of mediating adhesion of HT‐29 cells in vitro. In conclusion, these studies show that E‐selectin is heavily glycosylated with complex type N‐linked oligosaccharides and that N‐glycosylation is important for expression of E‐selectin on human endothelial cells.
Analysis of the natural human IgG antibody repertoire: life‐long stability of reactivities towards self antigens contrasts with age‐dependent diversification of reactivities against bacterial antigens
Authors: Lacroix‐Desmazes Sébastien , Mouthon Luc , Coutinho Antonio , Kazatchkine Michel D. 
Published: March 2007

AbstractWe used a quantitative immunoblotting technique to analyze the repertoires of IgG antibody reactivities in the serum of healthy young children, young adult males and aged males with self and non‐self antigens. Densitometric patterns of reactivity of purified IgG with self antigens were highly conserved between individuals within a given age group and across age groups. Inter‐individual differences were observed, however, upon analysis of self reactivities of IgG in whole serum. A striking heterogeneity between individuals within a given age group and across age groups characterized the reactivity of purified IgG and of IgG in whole serum with bacterial antigens. Inter‐individual differences were more marked among aged individuals than among individuals of other age groups. Analysis of variances of reactivities of IgG with bacterial antigens further demonstrated an increased diversity of repertoires of aged donors compared with those of young adults and children. Our results document the stability of the self‐reactive repertoires of IgG throughout life, which contrasts with the diversification of the repertoire of IgG antibody reactivities directed toward foreign antigens with aging. These findings support the concept that self‐reactive antibody repertoires are positively selected throughout life by a restricted set of self antigens shared by all individuals.
Incorporation of major histocompatibility complex – encoded subunits LMP2 and LMP7 changes the quality of the 20S proteasome polypeptide processing products independent of interferon‐γ
Authors: Kuckelkorn Ulrike , Frentzel Stefan , Kraft Regine , Kostka Susanne , Groettrup Marcus , Kloetzel Peter‐M. 
Published: March 2007

AbstractThe 20S proteasome is the enzyme complex responsible for the processing of antigens bound by major histocompatibility complex class I molecules. The role of the interferon‐γ (IFN‐γ)‐inducible proteasome subunits LMP2 and LMP7 in this process is, however, still controversial. We have studied the effects of IFN‐γ‐independent LMP incorporation on the quality of peptides processed from the murine cytomegalovirus IE pp89 25‐mer polypeptide substrate through dual cleavages by 20S proteasomes. The incorporation of a single LMP subunit or both LMP2 and LMP7 induces changes in 20S proteasome subunit stoichiometry, alters its cleavage site preference and in consequence, the quality of the generated peptides. When the several hydrolytic activities are tested with short fluorogenic peptide substrates, the Vmax, S0.5 (Km), or both values of 20S proteasomes are altered, depending on the combination of LMP. There exists, however, no obvious correlation between the observed changes in hydrolytic activities against short fluorogenic peptides and the changes in dual cleavage site usage within the 25‐mer polypeptide substrate. As judged from the calculated Hill coefficients, the presence of both LMP subunits induces a drastic increase in positive cooperativity between the proteasome subunits.
Interleukin‐10 differentially regulates B7‐1 (CD80) and B7‐2 (CD86) expression on human peripheral blood dendritic cells
Authors: Buelens Christel , Willems Fabienne , Delvaux Anne , Piérard Géraldine , Delville Jean‐Pierre , Velu Thierry , Goldman Michel 
Published: March 2007

AbstractMost of the immunosuppressive effects of interleukin‐10 (IL‐10) are related to functional inhibition of antigen‐presenting cells (APC). Herein, we investigate the influence of recombinant (r)IL‐10 on human dendritic cells (DC) purified from peripheral blood of healthy volunteers. First, we found that rIL‐10 inhibited in a dose‐dependent manner the proliferative responses as well as the production of IL‐2 and interferon‐γ (IFN‐γ) in mixed lymphocyte reaction (MLR) between purified T cells and DC. This rIL‐10 effect could be attributed to a direct effect on DC, as DC preincubated with rIL‐10 were found to be deficient in the induction of alloreactive T cells even when anti‐IL‐10 neutralizing mAb was added at the time of MLR. Flow cytometric analysis indicated that rIL‐10 did not modify the expression of ICAM‐1 (CD54) and B7‐1 (CD80), but decreased HLA‐DR and B7‐2 (CD86) expression at the DC surface. We conclude that the inhibitory effect of rIL‐10 on primary alloreactive T cell responses involves down‐regulation of class II MHC and B7‐2 expression at the DC surface.
Human naive CD4 T cells produce interleukin‐4 at priming and acquire a Th2 phenotype upon repetitive stimulations in neutral conditions
Authors: Demeure Christian E. , Yang Liang‐Peng , Byun Dae Gyoo , Ishihara Hideki , Vezzio Nadia , Delespesse Guy 
Published: March 2007

AbstractThe maturation of naive CD4 T cells into interleukin (IL)‐4‐producing effectors was shown to require the presence of IL‐4 at priming, the cellular origin of which remains unclear. We demonstrate here that naive T cells themselves release IL‐4 at very low levels that are nevertheless sufficient to promote their development into Th2‐like cells. This conclusion is based on three observations: (1) highly purified human naive CD4T cells, of neonatal or adult origin, develop into Th2 effectors upon repetitive cycles of stimulation with anti‐CD3 monoclonal antibody (mAb) cross‐linked to CD32‐B7 transfected L fibroblasts followed by IL‐2 expansion; (2) IL‐4 protein is readily detectable in the concentrated supernatant fluids of priming cultures performed in the presence of anti‐IL‐4 receptor mAb; and (3) addition of anti‐IL‐4 or anti‐IL‐4 receptor mAb at priming markedly inhibits the acquisition of IL‐4‐ and IL‐5‐producing capacity while enhancing that of interferon‐γ.