bluuebunny/crossref_metadata_2025_split huggingface dataset:
Down‐regulation of class II major histocompatibility complex molecules on antigen‐presenting cells by antibody fragments
Authors: Vidović Damir , Falcioni Fiorenza , Siklodi Botond , Belunis Charles J. , Bolin David R. , Ito Kouichi , Nagy Zoltan A. 
Published: March 2007

AbstractCertain HLA class II‐specific monoclonal antibodies (mAb) cause up to 90% decrease in the cell surface expression of class II molecules. This down‐regulation is isotype‐specific, i.e. DR‐specific mAb do not affect the expression of DP and DQ molecules. However, antibodies binding to one DR allotype down‐regulate both allotypes in heterozygous antigen‐presenting cells (APC), indicating that the phenomenon is not a direct consequence of ligation. All down‐regulating mAb identified recognize the first (peptide binding) domains of class II heterodimers, and strongly inhibit the activation of class II‐restricted human T cells in vitro. Conversely, non‐down‐regulating mAb fail to inhibit T cell activation, and most of them (four out of five) recognize class II second domains. Down‐regulating antibodies are cytotoxic for B lymphoblastoid cell lines and for a small proportion of normal activated B cells. Their F(ab′)2 fragments mediate both down‐regulation and cytotoxicity, whereas the monovalent Fab fragments are not cytotoxic, but retain the down‐regulatory and T cell inhibitory properties. These findings raise the possibility of a class II major histocompatibility complex‐specific, antibody‐based immunosuppressive therapy without cytotoxic side effects.
Precursor cells to CD3‐intermediate (CD3int) liver mononuclear cells in the adult liver: Further evidence for the extrathymic development of CD3int liver mononuclear cells
Authors: Kenai Hiroyuki , Matsuzaki Goro , Lin Tesu , Yoshida Hiroki , Nomoto Kikuo 
Published: March 2007

AbstractLiver mononuclear cells (LMNC) can be divided into CD3‐high positive (CD3hi), CD3‐intermediate positive (CD3int) and CD3− populations. CD3int LMNC, but not CD3hi LMNC, are considered to be extrathymically derived because they are found in the liver of nude mice and adult thymectomized lethally irradiated bone marrow chimeras. CD3int LMNC express NK1.1 and show a skewed T cell receptor (TCR) V region repertoire with relatively high levels of Vβ8 and Vα14 expression, further suggesting that they belong to a different lineage from conventional T cells, which lack NK1.1 expression and V region skewing. Since the liver has been proposed to be a site of extrathymic T cell differentiation in adult mice, we analyzed LMNC for the presence of T cell precursors. CD3− LMNC contained CD4−CD8− cells and CD4lo CD8− cells. Reverse transcription‐polymerase chain reaction analysis showed both CD3− populations express the recombination‐activating gene −1, which is indispensable in gene rearrangement of TCR and expressed by thymic T cell precursors. Furthermore, when electronically sorted CD3− LMNC were cultured in medium without any feeder cells or exogenously added cytokines for 24 h, CD3int cells, but not CD3hi cells, appeared. These results suggest that the adult liver contains T cell precursors that lack the expression of the CD3/TCR complex, but are strongly committed to differentiate into extrathymic liver CD3int T cells.
B1 and B2 cells differ in their potential to switch immunoglobulin isotype
Authors: Tarlinton David M. , McLean Michelle , Nossal Gustav J. V. 
Published: March 2007

AbstractThe ability of purified B1a (Ly‐1B) and B2 cells to switch immunoglobulin isotype was assessed by limiting dilution analysis in two in vitro culture systems. When stimulated in the presence of interleukins‐4 and −5 by either lipopolysaccharide or CD40 ligand, the frequency of IgG1 precursors in the B1a population was at most one third that of IgM precursors. In B2 cells, however, the frequency of IgG1 precursors was up to seven times that of IgM precursors. B1a cells were shown to respond to interleukin‐4 by virtue of up‐regulating major histocompatibility complex class II expression when exposed to the cytokine, precluding non‐responsiveness as a reason for not switching to IgG1. Indeed, interleukin‐4 was found to specifically induce transcription of the germ‐line IgG1 constant region locus in B1a cells as it did in B2 cells. Collectively these results suggest that the ability of B1 cells to respond to isotype switch commitment factors such as interleukin‐4 may be secondary to the production of IgM by these cells.
Interleukin‐2 down‐modulates memory T helper lymphocyte development during antigenic stimulation in vitro
Authors: Bemer Véronique , Motta Iris , Perret Raymond , Truffa‐Bachi Paolo 
Published: March 2007

AbstractUsing an in vitro antigenic stimulation model of murine spleen cells in the presence of the immunosuppressor cyclosporin A (CSA) we have previously reported that not only does this drug not interfere with the differentiation of T lymphocytes into memory cells it appears to favor this differentiation (Motta, I. et al., Eur. J. Immunol. 1991. 21: 551). Because CSA blocks interleukin‐2 (IL‐2) gene expression, we have analyzed the effect of this cytokine on memory T helper cell development. Murine splenic cells were primed for 6 days with sheep red blood cells (SRBC) in protocols in which either IL‐2 was not produced or its biological activity was neutralized by anti‐IL‐2 receptor (R) antibodies. The helper function of the recovered T cells was revealed by their capacity to help virgin B splenocytes produce anti‐SRBC antibodies upon challenge in vitro. We found that CD4+ cells primed in the absence of IL‐2, provoked either by IL‐2 gene transcription blockade by CSA or by treatment with anti‐IL‐2R antibodies, afford the best helper functions. These cells exhibit a memory‐type phenotype characterized by the low expression of the MEL‐14 marker and the high expression of the CD44 marker. Evidence is also presented that memory T helper cells originate in part from naive subset displaying the MEL‐14hi phenotype. The pattern of expression of the genes encoding different cytokines (IL‐2, IL‐4, IL‐5 and interferon‐γ) following a secondary antigenic stimulation shows that the helper function of the cells primed in the absence of IL‐2 correlates with the upregulation of the IL‐2 and the IL‐5 genes. From these data, we conclude that IL‐2 plays a major role in the control of memory T helper cell induction.
The Yaa gene‐mediated acceleration of murine lupus: Yaa− T cells from non‐autoimmune mice collaborate with Yaa+ B cells to produce lupus autoantibodies in vivo
Authors: Fossati Liliane , Sobel Eric S. , Iwamoto Masahiro , Cohen Philip L. , Eisenberg Robert A. , Izui Shozo 
Published: March 2007

AbstractThe BXSB Y chromosome‐linked mutant gene, Yaa, promotes autoimmune responses in mice predisposed to a lupus‐like autoimmune disease. We have previously shown that a cognate interaction of T cells with B cells expressing the Yaa gene appears to be responsible for the accelerated production of autoantibodies. To investigate whether T cells that provide help for autoantibody production by Yaa+ B cells need to express the Yaa gene, we have made radiation bone marrow chimeras containing two sets of T and B cells from mice with or without the Yaa gene and differing by the Thy‐1 and Igh allotypes. We then determined autoantibody production following the selective elimination of T cells of Yaa+ origin by treating mice with allele‐specific anti‐Thy‐1 monoclonal antibody. Our results demonstrated that the selective production of autoantibodies by Yaa+ B cells in Yaa+‐Yaa− double bone marrow chimeras can be mediated as efficiently by T cells from non‐autoimmune mice lacking the Yaa gene as by T cells from autoimmune mice bearing the Yaa gene. This indicates that T cells from non‐autoimmune Yaa− mice are capable of providing help for autoimmune responses by collaborating with Yaa+ B cells. These data thus strongly suggest that the Yaa gene defect is not functionally expressed in T cells, but only in B cells, and contrast with parallel experiments in the lpr model, in which defects of the Fas antigen in both T and B cells are crucial for the lpr gene‐mediated promotion of autoantibody production.
Bacterial superantigen specificities of mouse T cell receptor Vβ20
Authors: de Alba Yolanda Bravo , Cazenave Pierre‐André , Marche Patrice N. 
Published: March 2007

AbstractThe study of the mouse T cell receptor (TcR) β chain repertoire in BALB/c thymocytes led to the identification of the Vβ20 gene segment. The expression of Vβ20 estimated at the transcriptional level differs among mouse strains, suggesting clonal deletion. In the present study, we reconstituted by transfection functional TcR using the Vβ20 segment with different Vα segments and studied the action of superantigen toxins. The Vβ20‐transfectant T cells are activated by staphylococcal enterotoxins A and E (SEA and SEE) but not by the other tested toxins. The activation is dependent on the presence of cells expressing major histocompatibility complex class II molecules. Different HLA DR alleles can present the bacterial toxins, establishing that they interact with TcRVβ20 as super‐antigens. Moreover, the Vα domain associated with the Vβ20 domain has an influence on the response to these toxins. The fact that Vβ20 is recognized by SEA and SEE, although both toxins are known to interact with different sets of Vβ, suggests the presence of different TcR binding sites on the toxins.
Long‐term humoral and cellular immunity induced by a single immunization with replication‐defective adenovirus recombinant vector
Authors: Juillard Véronique , Villefroy Pascale , Godfrin Dominique , Pavirani Andrea , Venet Alain , Guillet Jean‐Gerard 
Published: March 2007

AbstractThis study examines the suitability of replication‐defective adenovirus vectors for engineering recombinant vaccines. The immunological abilities and limitations of E1‐deleted adenoviruses containing the lac Z gene (Ad‐β‐gal) were investigated by examining the humoral and cellular immune responses to the β‐galactosidase protein. BALB/c mice (H‐2d) were given in a single injection of recombinant adenovirus. The cytotoxic T lymphocyte (CTL) response of spleen cells was evaluated. Recognized target cells were H‐2d‐derived tumor cells transfected by the lac Z gene, or incubated with the 876–884 β‐galactosidase peptide known to be restricted by the Ld molecule of the major histocompatibility complex. A long‐lasting β‐galactosidase‐specific cytotoxic T cell response was obtained. By contrast, CTL from mice immunized with the Ld‐restricted peptide were less specific for the endogenous epitope presented by the transfectants expressing β‐galactosidase. Ad‐β‐gal‐immunized mice were also protected against an intra‐cerebral challenge with a recombinant vaccinia virus expressing the lac‐Z gene. These results suggest that Ad‐β‐gal‐induced CTL have protective abilities in vivo. The induction of β‐galactosidase‐specific T helper lymphocytes and humoral IgG responses were also examined. A proliferative response occurred only late after immunization and the primed T lymphocytes produced interleukin‐2, but no interleukin‐4. A humoral IgG response to the β‐galactosidase protein was detected 15–30 days after a single immunization and remained stable for 6 months without boosting. Lastly, we followed the evolution of the immune response over the course of successive immunizations. The magnitude and kinetics of the cellular and humoral responses were similar to those obtained after a single immunization. Consistent with these observations, an adenovirus‐specific neutralizing antibody response was detected as early as the second immunization. Thus, a single immunization with a replication‐defective adenovirus recombinant vector induces long‐lasting humoral and cellular immune responses specific to the transgene product.
IgD class switching: Identification of a novel recombination site in neoplastic and normal B cells
Authors: Kluin Philip M. , Kayano Hidekazu , Zani Valter J. , Kluin‐Nelemans Hanneke C. , Tucker Philip W. , Satterwhite Ed , Dyer Martin J. S. 
Published: March 2007

AbstractIgD on normal B lymphocytes usually is co‐expressed with IgM. A minority of normal plasma cells and rare B cell malignancies express exclusively IgD (IgM−‐IgD+). The low frequency has been explained by the lack of a recognizable switch region within the Cμ‐Cδ intron. We analyzed four cases of IgM−IgD+ hairy cell leukemia (HCL) by Southern (DNA) blot analysis and identified two cases with a recombinatorial event within the Cμ‐Cδ intron and deletion of Cμ. DNA sequence analysis of junctional regions showed that Sμ or the immediate upstream region was used as a donor site and that the Cμ‐Cδ intronic σδ region was used as acceptor site. Using polymerase chain reaction, we subsequently analyzed whether similar Sμ‐σδ recombinations occur in normal tonsils containing IgM−IgD+ plasma cells. Multiple products with a size range of 200–800 base pairs were detected in all four individuals, suggesting clustering of acceptor sites within σδ. Sequence analysis of three cloned products showed Sμ‐σδ recombinations similar those observed in HCL. The σδ region contains a relatively high content of pentameric repeats with an extremely G‐rich area and appears to function as a vestigial switch recombination site in normal and neoplastic IgM−‐IgD+ B cells.
Regulation of Fas(Apo‐1/CD95)‐ and perforinmediated lytic pathways of primary cytotoxic T lymphocytes by the protooncogene bcl‐2
Authors: Schröter Michael , Lowin Bente , Borner Christoph , Tschopp Jürg 
Published: March 2007

AbstractCytotoxic T cells (CTL) induce cell death of their target cells either by the surface interaction between Fas ligand and Fas or by the release of perforin and granzymes. Both lytic pathways induce apoptosis yet it is not known whether identical or distinct apoptotic pathways are activated. The protooncogene bcl‐2 is known to protect various hematopoietic cells from apoptosis induced by diverse agents. Here we show that overexpression of the Bcl‐2 protein in the murine mastocytoma line P815 or in concanavalin A‐activated splenocytes suppresses apoptotic cell death induced by allospecific primary cytotoxic T lymphocytes (CTL) in which only the Fas lytic pathway was functional. Bcl‐2 also reduced target cell killing induced by CTL whose lytic activity was dependent on the perforin/granzyme pathway only. These data provide evidence that, in the target cells studied here, both perforin/granzyme and Fas apoptotic pathways are modulated by Bcl‐2 and suggest that these two pathways converge at a step prior to Bcl‐2 inhibition.
Transdermal immunization with large proteins by means of ultradeformable drug carriers
Authors: Paul Amla , Cevc Gregor , Bachhawat Bemal K. 
Published: March 2007

AbstractBy means of novel, ultradeformable and self‐optimizing agent carriers called transfersomes, large molecules can be brought into the body through intact permeability barriers. This permits non‐invasive immunization through normal skin and gives rise to a similar or even slightly higher antibody titer than subcutaneous injections of the same immunogen formulation. The former type of immunization also results in a higher IgA/IgG ratio in the blood than the repeated immunogen injections, as shown here for a soluble protein, human serum albumin, as well as for an integral membrane protein, gap junction protein, in mice.
Enhanced inflammatory responses of chronic granulomatous disease leukocytes involve ROS‐independent activation of NF‐κB
Authors: Bylund Johan , MacDonald Kelly L. , Brown Kelly L. , Mydel Piotr , Collins L. Vincent , Hancock Robert E. W. , Speert David P. 
Published: March 2007

AbstractReactive oxygen species (ROS) generated by the cellular NADPH‐oxidase are crucial for phagocytic killing of ingested microbes and have been implicated as signaling molecules in various processes. For example, ROS are thought to be involved in activation of the transcription factor NF‐κB, central for mediating production of proinflammatory cytokines in response to inflammatory stimuli. Several studies have demonstrated that inhibitors of the NADPH‐oxidase interfere with NF‐κB activation and production of proinflammatory cytokines. Curiously, patients with chronic granulomatous disease (CGD), an immunodeficiency characterized by an inability to produce ROS, are not only predisposed to severe infections, but also frequently develop various inflammatory complications indicative of exaggerated inflammatory responses. Here, we show that human CGD leukocytes display a hyperinflammatory phenotype with increased production of proinflammatory cytokines in response to stimulation with Toll‐like receptor agonists. The hyperinflammatory phenotype was also evident in mononuclear cells from CGD mice (gp91phox–/–), but not in control cells in the presence of NADPH‐oxidase inhibitor diphenyleneiodonium, probably reflecting NADPH‐oxidase‐independent effects of the inhibitor. Furthermore, we show that the major steps involved in NF‐κB activation were intact in human CGD cells. These data indicate that ROS were nonessential for activation of NF‐κB and their production may even attenuate inflammation.
Regulated expression of the inhibitory receptor LAIR‐1 on human peripheral T cells during T cell activation and differentiation
Authors: Jansen Christine A. , Cruijsen Carin W. A. , de Ruiter Talitha , Nanlohy Nening , Willems Neeltje , Janssens‐Korpela Pirkko‐Liisa , Meyaard Linde 
Published: March 2007

AbstractThe leukocyte‐associated Ig‐like receptor‐1 (LAIR‐1) is capable of inhibiting immune cell function through interaction with collagens. LAIR is expressed on the majority of peripheral blood mononuclear cells. The abundant expression of both receptor and ligand calls for regulatory mechanisms to relieve the continuous interaction between collagens and LAIR‐1. This regulation may occur at the expression level of the receptor. Here, we report that LAIR‐1 is indeed differentially expressed during human T cell differentiation. Naive CD4+ and CD8+ T cells as well as CD8+ T cells of the effector phenotype express higher levels of LAIR‐1 compared to memory T cells. In vitro stimulation revealed a decrease in LAIR‐1 expression upon activation, and the lower LAIR‐1 expression on CD127– T cells suggests that activation‐induced down‐modulation of LAIR‐1 may also occur in vivo. Furthermore, crosslinking of LAIR‐1 on primary T cells results in an inhibition of T cell function. Our data suggest that regulated expression of LAIR‐1 and the subsequent change in the threshold for activation may be a mechanism to modulate inhibition of the immune system.
Nanocauliflowers: A Nanostructured Polyaniline‐Modified Screen‐Printed Electrode with a Self‐Assembled Polystyrene Template and Its Application in an Amperometric Enzyme Biosensor
Authors: Luo Xiliang , Vidal Gloria Domínguez , Killard Anthony J. , Morrin Aoife , Smyth Malcolm R. 
Published: March 2007

AbstractA simple method for the nanostructuring of polyaniline (PANI)‐modified screen‐printed electrodes (SPE) was developed. Polystyrene (PS) nanoparticles were self‐assembled onto a PANI‐modified SPE with the help of the negatively charged polyelectrolyte poly(sodium 4‐styrenesulfonate) (PSS) and positively charged poly(diallyldimethylammonium chloride) (PDDA). The self‐assembled PS nanoparticles could then act as a template for the electropolymerization of an additional layer of PANI. It was found that the additional layer of PANI preferred to grow around the PS nanoparticles, and a highly nodular, ‘cauliflower–like’ nanostructure of PANI was thus formed on the electrode surface, which was characterized by scanning electron microscopy. The SPE modified with the nanostructured PANI (nano‐PANI) was further used for the immobilization of horseradish peroxidase (HRP) and developed into a biosensor for hydrogen peroxide. Under optimized conditions, the proposed biosensor exhibited a fast response time of about 5 s, a linear range from 2.5×10−6 to 1.9×10−4 μM with a detection limit of 0.36 μM, and a high sensitivity of 41.0 μA mM−1 due to the benefits of the nanostructured PANI.
Evaluation of Accuracy of Electrochemical Isoflavonoid Index for the Determination of Total Isoflavones in Soy Samples
Authors: Escarpa Alberto , González María Cristina , Blasco Antonio Javier , del Carmen Rogerio Maria , Hervás Miriam 
Published: March 2007

AbstractThe accuracy of a novel electroanalytical route to determine total isoflavones using a secondary standard from Drug Master File (SW/1211/03) as metrological reference with well‐known traceability and its applicability using representative soy samples is demonstrated. Calibration protocols were used i) for choosing a suitable isoflavone standard to determine the total isoflavone content, ii) to evaluate matrix effects and, iii) to evaluate the overall reliability and performance of the method in analytical operations, extraction and analysis. The inherent electroactivity of both, aglycones and glycoside structures and the similar analytical sensitivity exhibited by the prominent soy isoflavones was relevant to determine the total amount with reliability in terms of accuracy (E<10%) and precision (RSDs<7%) in soy samples. In consequence, the introduction of the term isoflavonoid index as the total amount of isoflavones obtained when they are amperometrically monitorized at +1.0 V as a particular case of the electrochemical index concept is proposed.
Amperometric Glucose Biosensing of Gold Nanoparticles and Carbon Nanotube Multilayer Membranes
Authors: Liu Ying , Wu Shuo , Ju Huangxian , Xu Li 
Published: March 2007

AbstractA novel multilayer gold nanoparticles/multiwalled carbon nanotubes/glucose oxidase membrane was prepared by electrostatic assembly using positively charged poly(dimethyldiallylammonium chloride) to connect them layer by layer. The modification process and membrane structures were characterized by atomic force microscopy, scanning electron microscopy and electrochemical methods. This membrane showed excellent electrocatalytic character for glucose biosensing at a relatively low potential (−0.2 V). The Km value of the immobilized glucose oxidase was 10.6 mM. This resulting sensor could detect glucose up to 9.0 mM with a detection limit of 128 μM and showed excellent analytical performance.
Voltammetric Sensor for Sodium Nitroprusside Determination in Biological Fluids Using Films of Poly‐L‐Lysine
Authors: Pereira Francisco Claudece , Zanoni Maria Valnice Boldrin 
Published: March 2007

AbstractSodium nitroprusside (NP), a commercial vasodilator, can be pre‐concentrated on vitreous carbon electrode modified by films of 97.5%: 2.5% poly‐L‐lysine (PLL): glutaraldehyde (GA). This coating gives acceptable anion exchange properties whilst giving the required improvement of adhesion to the glassy carbon electrode surface. Linear response range and detection limit on nitroprusside in B‐R buffer pH 4.0, were 1×10−6 to 2×10−5 mol L−1 and 1×10−7 mol L−1, respectively. The repeatability of the proposed sensor, evaluated in term of relative standard deviation, was measured as 4.1% for 10 experiments. The voltammetric sensor was directly applied to determination of nitroprusside in human plasma and urine samples and the average recovery for these samples was around 95–97% without any pre treatment.
Copper Microelectrode as Liquid Chromatography Detector for Herbicide Glyphosate
Authors: Coutinho Cláudia F. B. , Coutinho Lincoln F. M. , Mazo Luiz H. , Lanças Fernando M. 
Published: March 2007

AbstractElectrochemical behavior of herbicide glyphosate at copper microelectrode was investigated in alkaline and buffer solutions, and two mechanisms seemed to take place for glyphosate: i) complexation reaction at lower potential in alkaline and buffer solutions and ii) catalysis process at higher potential in alkaline solution. It was demonstrated that the copper microelectrode can be used as coulometric detector for glyphosate in HPLC, using the complexation reaction in buffer solution. Under optimized conditions, the detection limit for glyphosate was 5.9×10−7 mol L−1. The present method was successfully applied to the determination of glyphosate in tomato juice with a recovery of 88%.