bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of anti‐carbohydrate antibodies by phage library‐selected peptide mimics
Authors: Phalipon Armelle , Folgori Antonella , Arondel Josette , Sgaramella Giuseppe , Fortugno Paola , Cortese Riccardo , Sansonetti Philippe J. , Felici Franco 
Published: March 2007

AbstractOne of the prerequisites for the development of polysaccharide subunit vaccines is the induction of an efficient immune response to carbohydrate antigens like lipopolysaccharide (LPS) or capsular polysaccharide antigens of pathogens. In an attempt to overcome the problems that arise from the T‐independent immune response induced by such antigens, selecting peptide sequences that mimic protective carbohydrate epitopes has been proposed. In this study, we investigate a new selection strategy for immunogenic peptide mimics using the phage displayed peptide library technology. Two monoclonal antibodies (mAb) of the A isotype (mIgA), mIgA C5 and mIgA I3, specific for the O‐antigen (O‐Ag) part of the human pathogen Shigella flexneri serotype 5a LPS and protective against homologous infection were used to screen two phage‐displayed nona‐peptide libraries in pVIII. Using mIgA C5, 13 different specific clones were selected, and 6 using mIgA I3; 5 of the latter also interacted in enzyme‐linked immunosorbent assay with the first mAb. All of the 19 clones selected were separately used to immunize mice, but only 2 of them, p100c (mIgA I3‐specific) and p115 (interacting with both mIgA) were able to induce anti‐O‐Ag antibodies. The immune response was specific for the O‐Ag of the S. flexneri serotype 5a, and also selectively recognized the corresponding bacterial strain. The amino acid sequences of p100c and p115 immunogenic peptide mimics were YKPL‐GALTH (flanked by two Cys residues) and KVPPWARTA, respectively. These results are the first example of immunogenic mimicry of carbohydrates by phage‐displayed peptides, and indicate a new strategy of selection of immunogens for the development of anti‐polysaccharide vaccines.
A Leishmania protein that modulates interleukin (IL)‐12, IL‐10 and tumor necrosis factor‐α production and expression of B7‐1 in human monocyte‐derived antigen‐presenting cells
Authors: Probst Peter , Skeiky Yasir A. W. , Steeves Michelle , Gervassi Ana , Grabstein Kenneth H. , Reed Steven G. 
Published: March 2007

AbstractLeIF, a gene homologue of the eukaryotic initiation factor 4A was first described as a leishmanial antigen that induced a Th1‐type T cell response in peripheral blood mononuclear cells (PBMC) from leishmaniasis patients. Moreover, the interferon (IFN)‐γ production by PBMC was found to be interleukin (IL)‐12 dependent. Herein, we characterize the effects of LeIF on cytokine production and expression of surface molecules by normal human monocytes as well as by monocyte‐derived macrophages and dendritic cells (MoDC). LeIF was a strong inducer of IL‐12 and, to a lesser extent, of IL‐10 and tumor necrosis factor (TNF)‐α in macrophages and MoDC. IL‐12 production did not require CD40 triggering, confirming that the ability of LeIF to induce IL‐12 was not mediated through an effect on T cells. However, addition of soluble CD40 ligand (L) synergistically augmented IL‐12 production in macrophages and MoDC. The cytokine‐inducing activity of LeIF is located in the N‐terminal portion of the molecule and was both proteinase K sensitive and polymyxin B resistant. LeIF, lipopolysaccharide and fixed Staphylococcus aureus all induced comparable amounts of IL‐12, validating the potent cytokine‐inducing effects of LeIF. Moreover, of these stimuli, LeIF had the highest IL‐12/IL‐10 and IL‐12/TNF‐α ratio demonstrating the preference of LeIF for IL‐12 induction. Studies investigating the expression of surface molecules showed that LeIF up‐regulated B7‐1 and CD54 (ICAM‐1) on macrophages and MoDC. To our knowledge this is the first report describing IL‐12 production, up‐regulation of co‐stimulatory and intercellular adhesion molecules by monocytic antigen‐presenting cells in response to a protein from a pathogenic microorganism. These immunomodulatory characteristics of LeIF might be excellent properties for a Th1‐type adjuvant.
Anti‐adhesive signals are mediated via major histocompatibility complex class II molecules in normal and neoplastic human B cells: Correlation with B cell differentiation stage
Authors: Ahsmann Els J. M. , Boom Saskia E. , Lokhorst Henk M. , Rijksen Gert , Bloem Andries C. 
Published: March 2007

AbstractWe show that major histocompatibility complex (MHC) class II molecules on B cells transmit signals which regulate adhesion in a negative manner. Engagement of MHC class II molecules with antibodies results in detachment of B cells previously bound to interferon‐γ‐activated human umbilical cord venous endothelial cells. This process depends on metabolic energy, active signaling and protein tyrosine kinase activity. The adhesion pathway influenced by this signaling event is neuraminidase sensitive. The anti‐adhesive signaling program is activated in B cell lines with a mature phenotype, e.g. normal B cells from spleen and tonsil. In contrast, cell lines with a pre‐B cell phenotype and normal B cells from peripheral blood are refractory to MHC class II‐mediated regulation of adhesion. These results extend to neoplastic cells from patients with lymphopro‐liferative diseases representing different stages of B cell maturation. These results suggest that MHC class II‐mediated signals regulate B cell adhesion in a developmentally programmed fashion; this might have implications for clinical behavior of B cell malignancies.
A re‐evaluation of the effects of X‐linked immunodeficiency (xid) mutation on B cell differentiation and function in the mouse
Authors: Klaus Gerry G. B. , Holman Mary , Johnson‐Léger Caroline , Elgueta‐Karstegl Claudio , Atkins Chris 
Published: March 2007

AbstractCBA/N (xid) mice have a point mutation in Bruton's tyrosine kinase (btk), which results in their failure to respond to T‐independent type 2 (TI‐2) antigens, and to several B cell mitogens [most notably anti‐immunoglobulin (Ig)] in vitro. They have reduced numbers of peripheral (B2) B cells, which are regarded as being phenotypically and functionally immature. We show here that adult CBA/N mice in fact have two distinct B cell populations: some 60% of the cells are CD23+ HSAlo sIgDhi and hence resemble recirculating, follicular (RF) B cells from normal mice, except that they are sIgMhi. The remaining 40% of xid B cells are CD23− HSAhi sIgD−/lo and resemble immature transitional (TR) B cells. TR B cells from xid mice do not synthesize DNA when cultured with lipopolysaccharide (LPS), whereas those from normal mice do so. Only the RF cells from either xid or normal mice proliferate in response to ligation of CD40. In neonatal normal mice the emergence of mitogen responsiveness followed the chronological sequence LPS → anti‐CD40 → anti‐Ig ≈ anti‐CD38. The same developmental sequence was seen with B cells from xid mice (for LPS and anti‐CD40), but it occurred at a significantly slower tempo and this correlated with the later appearance of RF‐type cells. TR xid B cells express very low levels of bcl‐2 and we conclude that these cells resemble very immature (bone marrow) B cells, rather than normal transitional cells. We, therefore, propose that the xid mutation imposes a multistage brake on B cell differentiation in the mouse. The available data suggest that btk is required for the positive selection of B cells throughout their differentiation in the periphery. This in turn implies that low level signaling via surface Ig is needed throughout this process in order for peripheral B cells to become functionally mature.
Rapamycin inhibits proteasome activator expression and proteasome activity
Authors: Wang Xin , Omura Satoshi , Szweda Luc I. , Yang Young , Bérard Jacques , Seminaro Johnny , Wu Jiangping 
Published: March 2007

AbstractRapamycin (RAPA) is a potent immunosuppressive drug, and certain of its direct or indirect targets might be of vital importance to the regulation of an immune response. In this study, we used differential hybridization to search for human genes whose expression was sensitive to RAPA. Seven RAPA‐sensitive genes were found and one of them encoded a protein with high homology to the α subunit of a proteasome activator (PA28α). This gene was later found to code for the β subunit of the proteasome activator (PA28β). Activated T and B cells had up‐regulated PA28β expression at the mRNA level. Such up‐regulation could be suppressed by RAPA, FK506, and cyclosporin A. RAPA and FK506 also repressed the up‐regulated PA28α messages in phytohemagglutinin (PHA)‐stimulated T cells. At the protein level, RAPA inhibited PA28α and PA28β in the activated T cells according to immunoblotting and confocal microscopy. Probably as a consequence, there was a fourfold increase of proteasome activities in the peripheral blood mononuclear cell lysate after the PHA activation. RAPA could inhibit the enhanced part of the proteasome activity. Considering the critical role played by the proteasome in degrading regulatory proteins, our data suggest that the proteasome activator is a relevant and important downstream target of rapamycin, and that the immune response could be modulated through the activity of the proteasome.
Expression of the Ly49A gene in murine natural killer cell clones is predominantly but not exclusively mono‐allelic
Authors: Held Werner , Raulet David H. 
Published: March 2007

AbstractThe Ly49 family of natural killer (NK) cell receptors are major histocompatibility complex (MHC) class I‐specific inhibitory receptors that are distributed to overlapping NK cell subsets. Extending earlier studies of polyclonal NK cell populations, we have employed an analysis of short‐term NK cell clones from Ly49A heterozygous mice, to demonstrate that the Ly49A gene is usually expressed from one or the other allele in each Ly49A+ cell. However, we also detected a small percentage of clones that expressed both Ly49A alleles. The possibility that the colonies exhibiting bi‐allelic Ly49A gene expression had been inoculated with more than one cell was ruled out by parallel analysis of clones isolated from mixtures of NK cells from Ly49A homozygous mice. The frequency of bi‐allelic Ly49A+ clones suggested that the two Ly49A alleles in an NK cell are chosen for expression independently. These data are consistent with the proposal that mono‐allelic Ly49A gene expression may arise as a consequence of a stochastic Ly49 gene activation mechanism. Analysis of Ly49A+ clones from MHC‐different mice demonstrated that class I‐deficient mice harbored a greater number of bi‐allelic Ly49A+ cells than did H‐2d mice, which express a Ly49A ligand. Although the numbers were insufficiently large for a clear assignment, H‐2b mice may harbor an intermediate number of bi‐allelic Ly49A+ NK cells. The effects of MHC expression on the prevalence of bi‐allelic Ly49A+ cells suggest that an MHC‐dependent education process modifies the Ly49 repertoire.
The roles of complement receptors type 1 (CR1, CD35) and type 3 (CR3, CD11b/CD18) in the regulation of the immune complex‐elicited respiratory burst of polymorphonuclear leukocytes in whole blood
Authors: Nielsen Claus H. , Antonsen Steen , Matthiesen Steen H. , Leslie R. Graham Q. 
Published: March 2007

AbstractThe binding of immune complexes (1C) to polymorphonuclear leukocytes (PMN) and the consequent respiratory burst (RB) were investigated in whole blood cell preparations suspended in 75% human serum, using flow cytometry. Blockade of the complement receptor (CR)1 receptor sites for C3b on whole blood cells using the monoclonal antibody (mAb) 3D9 resulted in a 1.9‐fold increase in the IC‐elicited PMN RB after 5 min of incubation, rising to 3.1‐fold after 40 min. This enhancement was not due to increased IC deposition on PMN. Blockade of CR3 abrogated the mAb 3D9‐induced rise in RB activity and inhibited the IC binding to PMN in a whole blood cell preparation, with or without mAb 3D9, by approximately 40% from 15–40 min while reducing their RB over 40 min to approximately one third. Blockade of CR1 on either erythrocytes (E) or leukocytes, before mixing the populations, revealed that the potentiation of the RB by mAb 3D9 was associated with abrogation of E‐CR1 function, whereas blockade of leukocyte‐CR1 had a diminishing effect. Exposure to IC at high concentrations induced release of both specific and azurophilic granule contents from PMN. The latter was CR3 dependent in that blockade of the receptor inhibited the lactoferrin release by one third during 40 min of incubation. In conclusion, CR3 plays a significant role in the IC‐mediated generation of an RB and release of specific granules by PMN, while CR1 on whole blood cells, primarily E CR1, restricts the IC‐elicited RB in PMN. We propose that CR1 in whole blood promotes the degradation of IC‐bound iC3b to C3dg, thereby rendering the IC inaccessible for binding to CR3.
In vivo rolling and endothelial selectin binding of mononuclear leukocytes is distinct from that of polymorphonuclear cells
Authors: Xie Xun , Raud Johan , Hedqvist Per , Lindbom Lennart 
Published: March 2007

AbstractIn inflammation, rolling of leukocytes along the microvascular endothelium is a precondition for subsequent integrin‐mediated firm adhesion and extravasation. Rolling characteristics of polymorphonuclear leukocytes (PMNL) and mononuclear leukocytes (MNL) in small venules (15–25 μm) of the rat mesentery were studied by intravital fluorescence microscopy under basal conditions and after intravenous treatment with an anti‐rat neutrophil serum (ANS). The baseline rolling fraction of the venular total leukocyte flux was 36 ± 15% (mean ± SD). The PMNL fraction of the systemic leukocyte count was 27 ± 9%. Treatment with ANS resulted in total depletion of circulating PMNL and reduced the leukocyte rolling fraction to 12 ± 5%, in this situation represented only by MNL. In rats treated intraperitoneally with interleukin (IL)‐1β for 4 h, the leukocyte rolling fraction was 53 ± 13% and was reduced to 33 ± 11% after ANS treatment. These data indicated that most, if not all, circulating PMNL rolled along the venular endothelial lining in the rat mesentery prepared for intravital microscopy, whereas MNL rolling was minor (∼ 10%) under the same basal condition. In cytokine‐activated tissue, on the other hand, the number of rolling MNL was greatly increased. While PMNL rolling is known to be entirely selectin dependent, the increased MNL rolling after IL‐1 stimulation was likely mediated by α4 integrins, inasmuch as the rolling fraction of isolated peripheral blood lymphocytes injected into the microcirculation of the cytokine‐stimulated mesentery was reduced from 31 ± 14% to 6 ± 2% by pre‐treatment of the cells with a monoclonal antibody against the rat integrin α4 chain. In accordance with the in vivo rolling characteristics of the two cell populations, binding of soluble P‐ or E‐selectin (selectin/IgG chimeras) was less intense for blood lymphocytes than for granulocytes, as determined by flow cytometric analyses of rat and human leukocytes. Taken together, our findings in vivo indicate that the adhesive interactions responsible for rolling of PMNL and MNL, respectively, are distinct in terms of receptor occupancy, and may help explain the temporal selectivity in recruitment of different leukocyte subpopulations in inflammatory or immune reactions.
αβ Lineage‐committed thymocytes can be rescued by the γδ T cell receptor (TCR) in the absence of TCR β chain
Authors: Livák Ferenc , Wilson Anne , MacDonald H. Robson , Schatz David G. 
Published: March 2007

AbstractCommitment of the αβ and γδ T cell lineages within the thymus has been studied in T cell receptor (TCR)‐transgenic and TCR mutant murine strains. TCRγδ‐transgenic or TCRβ knockout mice, both of which are unable to generate TCRαβ‐positive T cells, develop phenotypically αβ‐like thymocytes in significant proportions. We provide evidence that in the absence of functional TCRβ protein, the γδTCR can promote the development of αβ‐like thymocytes, which, however, do not expand significantly and do not mature into γδ T cells. These results show that commitment to the αβ lineage can be determined independently of the isotype of the TCR, and suggest that αβ versus γδ T cell lineage commitment is principally regulated by mechanisms distinct from TCR‐mediated selection. To accommodate our data and those reported previously on the effect of TCRγ and δ gene rearrangements on αβ T cell development, we propose a model in which lineage commitment occurs independently of TCR gene rearrangement.
Hypermutation, diversity and dissemination of human intestinal lamina propria plasma cells
Authors: Dunn‐Walters Deborah K. , Boursier Laurent , Spencer Jo 
Published: March 2007

AbstractIn this work we have microdissected lamina propria plasma cells and used polymerase chain reaction and sequencing to investigate immunoglobulin (Ig) gene rearrangements and mutations in human intestine. In addition, specific primers were designed for individual Ig gene rearrangements to analyze the distribution of related B cell and plasma cell clones at different sites along the bowel. Confirming our earlier work, intestinal IgVH genes were highly mutated in plasma cells from older individuals (> 30 years). IgVH genes were significantly less mutated in samples taken from patients aged 11–30 years, and there were fewer mutations again in samples from young children (< 11 years). In age‐matched specimens the number of mutations was equivalent in the duodenum and colon. Using complementarity‐determining region 3 primers to amplify specific Ig gene rearrangements, evidence was also found for the existence of related lamina propria plasma cells along the small bowel and colon, although these were quite scarse. In addition, analysis of the numbers of related clones in a random sampling from discrete areas of lamina propria indicates that the local population is diverse. These results suggest that the highly mutated IgVH genes in adult intestinal plasma cells are a consequence of chronic antigen exposure with age. Duodenal plasma cells are as highly mutated as colonic plasma cells, despite the fact that the upper bowel has no indigenous microbial flora (the stimulus for intestinal plasma cells). They also show that the plasma cell population is diverse and can be widely disseminated along the bowel.
Analysis of immunoreceptor tyrosine‐based activation motif (ITAM) binding to ZAP‐70 by surface plasmon resonance
Authors: Vély Frédéric , Nunès Jacques A. , Malissen Bernard , Hedgecock Charles J. R. 
Published: March 2007

AbstractThe signaling function of the T cell antigen receptor (TCR) is mediated via CD3 polypeptides, the cytoplasmic sequences of which bear conserved immunoreceptor tyrosine‐based activation motifs (ITAM). ITAM are defined by two YxxL/I sequences separated by a six–eight amino acid long spacer. Upon antigen recognition, ITAM become phosphorylated on both tyrosine residues, creating a high affinity binding site for the tandem SH2 domains found in the protein tyrosine kinase ZAP‐70. Using surface plasmon resonance, we further dissected the sequences required for the binding of ZAP‐70 to each TCR‐associated ITAM. First, we generated protein tyrosine phosphatase‐resistant ITAM peptide analogs, in which difluorophosphonomethyl phenylalanyl (F2P) replaced both phosphotyrosines, and showed that those protein tyrosine phosphatase‐resistant analogs bind ZAP‐70 with high affinity, establishing a rational strategy for the design of novel pharmacological tools capable of interfering with TCR signaling function. Second, we substituted the five amino acids separating the two YxxL/I sequences of the CD3ζ1 ITAM with a non‐peptidic linker made up of γ‐amino butyric acid units and demonstrated that the length of this intervening sequence rather than its chemical composition is essential for high affinity binding of phosphorylated ITAM to the ZAP‐70 SH2 domains.
Molecular mechanisms regulating induction of interleukin‐6 gene transcription by interferon‐γ
Authors: Faggioli Laura , Merola Marcello , Hiscott John , Furia Adriana , Monese Rossana , Tovey Michael , Palmieri Marta 
Published: March 2007

AbstractThe multifunctional cytokine interleukin‐6 (IL‐6) plays a central role in host defence mechanisms and hematopoiesis. Furthermore, dysregulation of IL‐6 gene expression is associated with the pathogenesis of various immunologically related diseases such as myeloma, systemic lupus erythematosus, rheumatoid arthritis, psoriasis and Kaposi's sarcoma. The regulation of IL‐6 gene expression occurs mainly at transcriptional level, although mechanisms of post‐transcriptional regulation have also been described. In the present study we demonstrate that in HeLa cells, induction of IL‐6 by interferon‐γ (IFN‐γ) is transcriptionally controlled, as shown by run on assays and analysis of the IL‐6 mRNA stability. Gel‐retardation experiments using antibodies specific for factors of the IRF family identified four protein‐DNA complexes, which bind to the interferon regulatory factor (IRF) binding site at position −267 to −254, in nuclear extracts from IFN‐γ treated cells. Furthermore, transient transfection analyses of the 5′‐flanking region of IL‐6 gene linked to the chloramphenicol acetyltransferase (CAT) reporter gene demonstrated that the −267 to −254 IRF site is necessary for IL‐6 induction by IFN‐γ. However, transfection experiments in which IRF‐1 and IxBα were overexpressed show that full‐scale transcriptional activation of the IL‐6 promoter directing CAT expression requires the co‐operation between IRF‐1 and NF‐xB at a low constitutive level.
Human immunodeficiency virus type‐1‐specific immune responses induced by DNA vaccination are greatly enhanced by mannan‐coated diC14‐amidine
Authors: Sasaki Shin , Fukushima Jun , Arai Hiroyuki , Kusakabe Ken‐Ichi , Hamajima Kenji , Ishii Norihisa , Hirahara Fumiki , Okuda Katsuji , Kawamoto Susumu , Ruysschaert Jean‐Marie , Vandenbranden Michel , Wahren Britta , Okuda Kenji 
Published: March 2007

AbstractUse of mannan‐coated N‐t‐butyl‐N′‐tetradecyl‐3‐tetradecylamino‐propion‐amidine (diC14‐amidine) as an adjuvant for a DNA vaccine encoding glycoprotein 160 of human immunodeficiency virus type‐1 (HIV‐1) enhanced the antigen‐specific immune responses. The role of interferon‐γ (IFN‐γ) and interleukin‐12 in the mechanism of adjuvant action was also evaluated. Coating of diC14‐amidine with mannan significantly augmented the HIV‐specific delayed‐type hypersensitivity reaction induced by the immunogenic DNA. HIV‐1‐specific cytotoxic T lymphocyte activity was also markedly enhanced by the mannan‐diC14‐amidine cocktail. An immunomodulatory effect of this cocktail was inhibited by treatment with anti‐IFN‐γ monoclonal antibody in vivo, which suggests that IFN‐γ plays an important role in inducing cell‐mediated immunity by the DNA vaccine containing this adjuvant. The results of both antigen‐specific immunoglobulin isotype analysis and cytokine measurement showed that the immunogenic DNA incorporated into mannan‐coated diC14‐amidine elicits Th1‐biased immune responses.