bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction between Epstein‐Barr virus and a T cell line (HSB‐2) via a receptor phenotypically distinct from complement receptor type 2
Authors: Hedrick Joseph A. , Watry Debbie , Speiser Catherine , O'Donnell Patrick , Lambris John D. , Tsoukas Constantine D. 
Published: March 2007

AbstractEpstein‐Barr virus (EBV), the causative agent of mononucleosis and several human cancers, infects cells via complement receptor type 2 (CR2, CD21) which also serves as the receptor for the third complement component, C3. Expression of this receptor is restricted to B lymphocytes, immature thymocytes, and certain epithelial cells. In the present investigation, we describe the presence of a seemingly novel EBV receptor which is phenotypically distinct from CR2. Among various leukemic T cells studied, one, HSB‐2, demonstrates no reactivity to several anti‐CR2 antibodies, yet it reacts strongly with EBV as detected by incubation with biotin‐conjugated virus and streptavidin‐phycoerythrin. The virus binding is specific as demonstrated by blocking with anti‐EBV antibodies and with non‐conjugated virus. Aggregated C3 also binds HSB‐2 and is capable of partially inhibiting EBV binding. The absence of CR2 on HSB‐2 is further supported by the lack of expression of specific mRNA, assessed by Northern blotting analysis and polymerase chain reaction. Viral internalization and infection is demonstrated with electron microscopy, with detection of EBV‐DNA by Southern blotting, and with detection of EBNA‐1 transcripts by the polymerase chain reaction. Even though HSB‐2 does not express CR2, it nevertheless displays transcripts which have some homology to a CR2 cDNA probe under low stringency hybridization conditions. This probe encompasses approximately the N‐terminal half of CR2 which includes the EBV‐binding epitope(s). The HSB‐2 message is 5.2 kb, a size distinct from the 4.7‐kb message of B cell CR2s. In contrast, the 5.2‐kb message in not seen, under similar hybridization conditions, with a probe comprising the C‐terminal half of CR2. Collectively, the data indicate that a receptor molecule having distinct phenotypic characteristics from the known CR2 protein on B cells is utilized by EBV to target human T lymphocytes.
Cell cycle‐dependent regulation of CDw75 (β‐galactoside α‐2,6‐sialyltransferase) on human B lymphocytes
Authors: Erikstein Bjørn K. , Funderud Steinar , Beiske Klaus , Aas‐Eng Anne , De Lange Davies Catharina , Blomhoff Heidi Kiil , Smeland Erlend B. 
Published: March 2007

AbstractWithin the hematopoietic system, CDw75 is primarily expressed on cells of the B cell lineage. Cloning and sequencing of the gene has shown CDw75 to be a β‐galactoside α‐2,6‐sialyltransferase. This enzyme plays an important role in the intracellular terminal glycosylation pathways in various cell types. In this article, we demonstrate that COS cells transfected with the CDw75 cDNA clone displayed sialyltransferase activity, in contrast to mock‐transfected cells. We also found that activated B cells displayed an increased enzyme activity compared to resting cells, in accordance with the staining data. Moreover, CDw75 expression was found to be up‐regulated approximately 7‐9‐fold from early G1 to the G2/M phases of the cell cycle in peripheral blood leukocyte B cells. This was shown by staining of in vitro activated B cells with the anti‐CDw75 monoclonal antibody HH2, using cell fractions corresponding to different stages of the cell cycle. Using a combination of Hoechst 33258 and propidium iodide after bromodeoxyuridine incorporation, it is possible to distinguish between different phases of the first and second cell cycle. By combining this with HH2 immunofluorescence staining, using a multistation multiparameter flow cytometry program, we confirmed the cell cycle‐dependent expression of CDw75. Immunocytochemical stainings of cytospin specimens of elutriated B cells showed that the antigen was up‐regulated in late G1 before the appearance of the nuclear activation antigen Ki67. Finally, we showed that activated B cells secreted soluble CDw75 into the medium, as demonstrated by a specific blocking of HH2 staining of B cells using suboptimal concentrations of HH2. In accordance with this, we observed small, but detectable levels of soluble sialyltransferase activity in supernatants of activated B cells.
Regulation of the p59fyn protein tyrosine kinase by the CD45 phosphotyrosine phosphatase
Authors: Mustelin Tomas , Pessa‐Morikawa Tiina , Autero Matti , Gassmann Martin , Andersson Leif C. , Gahmberg Carl G. , Burn Paul 
Published: March 2007

AbstractTriggering of the T cell antigen receptor/CD3 (TcR/CD3) complex leads to rapid tyrosine phosphorylation of regulatory proteins that participate in initiating T cell activation and proliferation. This signal transduction event requires the presence of the TcR/CD3‐associated protein tyrosine kinase p59fyn. There is also evidence that the CD45 phosphotyrosine phosphatase is involved in TcR/CD3 signalling. We show here by capping experiments using double indirect immunofluorescence techniques that the receptor phosphotyrosine phosphatase CD45 and the intracellular protein tyrosine kinase p59fyn specifically co‐distribute in functional T lymphocytes. Furthermore, we provide evidence that isolated p59fyn is a substrate for CD45 as indicated by the rapid dephosphorylation of the regulatory Tyr531 of p59fyn by CD45. This dephosphorylation is accompanied by a severalfold increase in the catalytic activity of p59fyn as measured by its autophosphorylation and phosphorylation of an exogenous substrate. We also demonstrate that CD45‐mediated dephosphorylation and activation of p59fyn apparently occurs at a slow basal rate in resting T cells. This represents the first identification of a physiologic regulator of p59fyn and implies a mechanism for the role of CD45 in TcR/CD3 signal transduction.
Analysis of cytokine mRNA levels in interleukin‐4‐transgenic mice by quantitative polymerase chain reaction
Authors: Platzer Cornelia , Richter Günther , Überla Klaus , Müller Werner , Blöcker Helmut , Diamantstein Tibor , Blankenstein Thomas 
Published: March 2007

AbstractInterleukin (IL)‐4‐transgenic mice were used as a model system to study the consequences of low levels of IL‐4 expression for the expression of other cytokines examined by quantitative polymerase chain reaction (PCR). For this purpose, a plasmid was constructed which contains, in tandem array, 5′ and 3′ primer sequences specific for the cytokine genes IL‐1 to IL‐6, tumor necrosis factor (TNF), lymphotoxin (LT), interferon (IFN)‐γ and β‐actin. During co‐amplification, target and control DNA complete for the primers and the amount of PCR product is proportional to the amount of input DNA. Competitive PCR was performed first to adjust the cDNA to be compared to identical concentrations of β‐actin cDNA and subsequently to determine cytokine mRNA levels from spleen cells of normal and IL‐4‐transgenic animals. The sensitivity of this approach was demonstrated by the capability to detect a twofold difference in IL‐4 mRNA levels between IL‐4‐transgenic heterozygous and homozygous animals. Upon lipopolysaccharide activation, the IL‐4 transgene which is expressed essentially in B lymphocytes was induced approximately 50‐fold. Several cytokine mRNA such as those coding for IL‐5, IL‐6, IFN‐γ and also the IL‐4 receptor were found to be up‐regulated in IL‐4‐transgenic mice, whereas IL‐1, IL‐2, IL‐3, TNF and LT mRNA levels did not seemed to be influenced by IL‐4. A possible functional significance of the elevated IFN‐γ mRNA was demonstrated by showing that (a) CD23 expression was not increased, and (b) Mac‐1+ cells were markedly increased in the spleen of transgenic mice.
Expression of perforin in murine natural killer cells and cytotoxic T lymphocytes in vivo
Authors: Kawasaki Akemi , Shinkai Yoichi , Yagita Hideo , Okumura Ko 
Published: March 2007

AbstractWe have previously detected perforin expression in a subpopulation of asialo GM1+ natural killer (NK) cells and CD8+ T lymphocytes in murine spleen cells by immunocytochemical staining with an anti‐perforin monoclonal antibody. In the present study, more datailed analyses of perforin expression in murine cytotoxic lymphocyte subpopulations were performed. The expression of perforin in asialo GM1+ spleen cells was predominantly confined to the NK1.1+ subset, where all NK activity also resided. Perforin expression was also studied on alloreactive cytotoxic T lymphocyte (CTL) induced in vivo. The cells expressing perforin in peritoneal exudate lymphocytes predominantly resided in the CD8+ T cell subpopulation co‐expressing asialo GM1 where an allospecific CTL activity also resided. Furthermore, the percentage of perforin‐positive cells in this population was greatly reduced after stimulation with anti‐CD3 or anti‐T cell receptors antibodies, which induce serine esterase release from the cytoplasmic granules. These findings highly suggest that perforin is involved in in vivo NK cell and CTL‐mediated cytolysis.
Interleukin (IL)‐4 production by human T cells: differential regulation of IL‐4 vs. IL‐2 production
Authors: Van der Pouw‐Kraan Tineke , Van Kooten Cees , Rensink Irma , Aarden Lucien 
Published: March 2007

AbstractWe have examined the regulation of interleukin (IL)‐4 production by human peripheral blood T cells. Production of IL‐4 was shown to be regulated differently from IL‐2 and interferon(IFN)‐γ production. Stimulation of peripheral blood lymphocytes with anti‐CD3, anti‐CD2, anti‐CD28, Phorbol 12‐myristate 13‐acetate (PMA) or IL‐2 as a single stimulant did not induce IL‐4 production. However, combinations of anti‐CD2 with either anti‐CD28 or IL‐2 resulted in IL‐4 production, peaking at days 3–4. Stimulation with anti‐CD3 instead of anti‐CD2 gave similar results, but was less potent. After days 3–4, IL‐4 levels decreased, most likely due to consumption of IL‐4. PMA profoundly affected cytokine production, it enhanced IL‐2 production by at least tenfold, whereas, in the same cell population, IL‐4 production was almost completely inhibited. This was observed at the protein as well as at the mRNA level. In contrast, agents that increase intracellular cAMP levels inhibited IL‐2 production but left IL‐4 production unaffected. IFN‐γ production behaved similar to IL‐2 production but the effects were less outspoken.
Specificity of antigen processing for MHC class I restricted presentation is conserved between mouse and man
Authors: Falk Kirsten , Rötzschke Olaf , Rammensee Hans‐Georg 
Published: March 2007

AbstractAlloreactive mouse cytotoxic T lymphocytes (CTL) specific for particular peptides presented by H‐2Kb molecules on mouse cells were found to recognize human cells transfected with Kb. The CTL‐recognized peptides (probably derived from conserved proteins) were extracted from Kb‐expressing human or mouse cells, respectively, and compared biochemically by high resolution high performance liquid chromatography. The results strongly suggest identity of peptides processed by cells from both species and thus indicate that the specificity of the processing machinery used in the major histocompatibility complex (MHC) class I‐restricted pathway, probably including enzymes, transport mechanisms, and chaperons, is highly conserved across species. The results are consistent with the notion that MHC molecules themselves have an instructive role in processing.
Secretion of interleukin‐8 following phagocytosis of Mycobacterium tuberculosis by human monocyte cell lines
Authors: Friedland Jon S. , Remick Daniel G. , Shattock Rubin , Griffin George E. 
Published: March 2007

AbstractTuberculosis is a major cause of mortality worldwide and incidence is increasing asaresult of the AIDS epidemic. Cytokines such as tumor necrosis factor (TNF) are important in the host response to Mycobacterium tuberculosis. TNF is involved in both granuloma formation and has direct anti‐mycobacterial activity. This study investigated the secretion of interleukin (IL)‐8 following phagocytosis of M. tuberculosis by a human monocytic cell line and by a more phenotypically mature macrophage‐like cell line. M. tuberculosis is shown to be a more potent inducer of IL‐8 but not of TNF than bacterial lipopolysaccharide invitro in bothcell types. IL‐8 production is partly a consequence of accumulation of mRNA coding for this cytokine. Secretion of IL‐8 is not a simple consequence of the phagocytic process but due to the specific interaction M. tuberculosis and the monocyte. IL‐8 production was independent of TNF and of virulence of the strain of M. tuberculosis. IL‐8 secretion following phagocytosis of M. tuberculosis suggests that this cytokine may be involved in granuloma formation in vivo, possibly acting, in part, as a T cell chemoattractant.
Engagement of class I major histocompatibility complex molecules by cell surface CD8 delivers an activation signal
Authors: Geppert Thomas D. , Nguyen Hoan , Lipsky Peter E. 
Published: March 2007

AbstractRecent evidence has demonstrated that cross‐linking class I major histocompatibility complex (MHC) molecules on human T cells with monoclonal antibodies (mAb) triggers T cell activation. The only known natural ligand for MHC class I molecules is CD8.Therefore, the possibility that CD8+ T cells might provide activation signals to other T cells by engaging MHC class I molecules was examined by culturing CD4+ peripheral blood T cells with Chinese hamster ovary cells (CHO) cells that had been transfected with the α chain or α and β chains of CD8 and assessing interleukin (IL)‐2 production. CD4+ T cells did not secrete IL‐2 when cultured alone, with control or CD8+ CHO cells. In contrast, CD4+ T cells produced IL‐2 when cultured with CD8+ CHO cells and co‐stimulated with phorbol myristate acetate (PMA) or mAb to CD3 or CD28. PMA stimulated substantially less IL‐2 when control CHO cells were employed and the mAb to CD3 and CD28 did not stimulate IL‐2 production in the presence of control CHO cells. The co‐stimulatory activity of CD8+CHO cells was completelyeliminated by mAb to CD8 or MHC class I molecules. The data demonstrate that CD8 can interact with MHC class I molecules expressed on T cells and deliver a costimulatory signal that increases IL‐2 production. Thus, engagement of MHC class I molecules byits natural ligand, CD8, provides an activation signal to T cells. Under some circumstances, such interactions may amplify the responses of T cells.
Thymic epithelium induces neither clonal deletion nor anergy to Mls 1a antigens
Authors: Bandeira António , Coutinho António , Burlen‐Defranoux Odile , Khazaal Ibrahim , Coltey Monique , Jacquemart Frederic , Douarin Nicole Le , Salaün Josselyne 
Published: March 2007

AbstractGrafting of thymic anlagen from day‐10 DBA/2 (H‐2d; Mls‐1a) embryos to newborn athymic BALB/c (H‐2d; Mls‐1b) mice leads to reconstitution of T cell populations in the recipients. Analysis of adult chimeras shows that their Vβ T cell receptor (TcR) repertoires, particularly Vβ6 and Vβ8.1, do not significantly differ in most animals (10 out of 13) from those scored in control chimeras that received syngeneic thymic anlagen. In all cases analyzed, such Mls‐1a−reactive T cells could be stimulated at levels comparable to control responses, both in vitro and in vivo. The few cases in which Mls‐1a reactive Vβ TcR were reduced seem to reflect the variability in TcR Vβ repertoires found inthis experimental system. In contrast, BALB/c mice, injected at birth with DBA/2spleencells show a marked, albeit variable, reduction in the frequencies of Vβ6− and Vβ8.1‐bearing CD4+ T cells, and lower frequencies of Mls‐1a−reactive T cells in limiting dilution analyses. It appears, however, that Vβ6− and Vβ8.1‐bearing T cells remaining in these mice are functionally competent. We conclude that Mls‐1antigens are not expressed by thymic epithelium.
Synthetic peptide libraries in the determination of T cell epitopes and peptide binding specificity of class I molecules
Authors: Schumacher Ton N. M. , Van Bleek Grada M. , Heemels Marie‐ThéRèSe , Deres Karl , Li Ka Wan , Imarai Monica , Vernie Leen N. , Nathenson Stanley G. , Ploegh Hidde L. 
Published: March 2007

AbstractMajor histocompatibility complex (MHC) class I molecules combine with short peptides of defined length and sequence. Here we describe an approach that may be used in the analysis of peptide preference of different allelic MHC class I molecules, and in the determination of T cell epitopes. We produced synthetic “peptide libraries” of limited complexity by standard peptide chemistry. Using these peptide mixtures we show that H‐2 Kb molecules can accomodate both 8‐and 9‐residue peptides, whereas Db molecules are unable to combine with peptides shorterthan 9 amino acids present in these libraries. When these peptide mixturesare used to provide “fingerprints” of Db molecules and mutants thereof, both loss and gain of the ability to combine with certain peptides is observed. For the Kbm1 mutant a strong influence of amino acid substitutions in class I molecules on the peptides selected is observed. In these synthetic peptide mixtures, the presence ofa specific T cell epitope, known to be represented once, can be detected. This approachmay be extended to the identification of new T cell epitopes from largerpeptide libraries.
Cell surface display of rat invariant γ chain: detection by monoclonal antibodies directed against a C‐terminal γ chain segment
Authors: Fisch Andreas , Reske Konrad 
Published: March 2007

AbstractA series of 14 monoclonal antibodies (mAb) directed against the C‐terminal part of the rat invariant γ chain (amino acid 142–216) was generated using distinct fusion proteins that contain this γ segment for immunization and hybridoma screening. Additional fusion proteins were prepared carrying discrete regions of the γ chain. Employing these reagents confirmed that the obtained mAb do indeed recognize the C‐terminal portion of the invariant chain, as demonstrated by Western blot analysis. All mAb established recognize epitopes present on the native γ chain, as revealed by immunoprecipitation analysis using nonionic detergent extracts of metabolically labeled Lewis rat splenocytes combined with two‐dimensional gel electrophoresis. However, while the majority of the γ chain‐specific mAb precipitated γ chain‐containing polypeptide chain complexes in which immature, sialic acid‐deficient and mature, terminally sialylated forms of the γ chain were predominantly represented, a fraction of the antibodies preferentially precipitated the immature γ forms. Cell surface binding of these two groups of mAb correlated with the immunoprecipitation data in that the former group of antibodies did bind to intact Lewis rat spleen cells, while essentially no binding was observed with the antibodies of the latter group. Double‐fluorescence staining with the class II‐specific fluorescein isothiocyanate‐conjugated mAb OX3 andOX6, respectively, as well as a representative γ chain‐specific mAb visualized with phycoerythrin‐coupled secondary antibody shows coexpression of class IIdeterminants and the invariant chain at the cell surface.
Human‐mouse lymphoid chimeras: host‐vs.‐graft and graft‐vs.‐host reactions
Authors: Murphy William J. , Bennett Michael , Anver Miriam R. , Baseler Michael , Longo Dan L. 
Published: March 2007

AbstractHuman peripheral blood lymphocytes (huPBL) were injected into mice with severe combined immune deficiency (SCID). It was ascertained that murine natural killer (NK) cellswere capable of affecting engraftment of human lymphocytesin SCID mice. The presence of host NK cells resulted in the clearance of the human lymphocytes. Human T lymphocyteswere the primary cell to engraft in the SCID recipients, with human T cells being detected in the spleen, lymph nodes, bone marrow and peritoneal cavity of the mice up to several months after transfer. No human T cells were detected in the murine thymus and thelevel of engraftment in the periphery could be highly variable. Additionally, there appeared to be significant reactions between the human lymphocytes and the murine host resulting in a xenogeneic graft‐vs.‐host reaction (XGVHR). The predominant manifestation involved splenomegaly resulting from an expansion of murine hematopoietic cells in the spleens of these xenogeneic chimeras. The severity of the XGVHR could be correlated with the extent of human T cell engraftment and the recovered human Tcells were found to be in a proliferative state. Thus, there appear to be significant host‐vs.‐graft and graft‐vs.‐host interactionsoccurring in human/mouse lymphocyte chimeras.
Changes in expression of CD45R during the development of Th1 and Th2 cell lines
Authors: Lee William T. , Vitetta Ellen S. 
Published: March 2007

AbstractPrevious studies using anti‐CD45R monoclonal antibodies (mAb) have shown that normal CD4+ T cells can be separated into virgin and memory cells basedon their level of expression of CD45R. CD45Rhi (virgin)T cells secrete interleukin (IL)‐2 whereas CD45Rlo (memory) T cells secrete both IL‐2 and IL‐4. In contrast to these results, studies using cultured T cell lines haveshown that IL‐2‐secreting T helper cell type 1 (Th1) cells are CD45Rlo and IL‐4‐secreting Th2 cells are CD45Rhi. To resolve this discrepancy, and to determine how the Th1 and Th2 cell lines relate to memory CD45Rlo and virgin CD45Rhi CD4+ T cells, we have isolated CD45Rlo cells from alloantigen‐primed mice and developed allospecific Th1 and Th2 cell lines. The lymphokinessecreted by these lines were then evaluated. Our results show that as CD45Rlo T cells develop into in vitro cell lines which secrete IL‐4, they become CD45Rhi. In contrast, CD45Rlo cells that develop into lines which secrete IL‐2 maintain their CD45Rlo phenotype. Thus, although both Th1 and Th2 cells arise initially from CD45Rlo cells, Th2 cells become CD45Rhi during prolonged in vitro culture but, Th1 cells do not.
Staphylococcal enterotoxin B as a potent suppressant of T lymphocytes: trace levelssuppress T lymphocyte proliferative responses
Authors: Ben‐Nun Avraham , Yossefi Sara 
Published: March 2007

AbstractStaphylococcal enterotoxins have long been known to be powerful stimulators of T lymphocytes in mouse and man. In a previous study we showed that high concentrations of staphylococcal enterotoxin serotype B (SEB) failed to stimulate strong proliferative responses by Lewis rat T lymphocytes. Moreover, concentrations of SEB (10–50 μg/ml) that stimulated optimal mouse T lymphocyte proliferative responses suppressed a mitogen‐ or antigen‐induced rat T lymphocytes proliferative responses. The present study shows that SEB at low concentrations (as low as 10−3−10−4 μg/ml) and often also trace levels (about 10−610−7 μg/ml) suppresses both rat and mouse T lymphocytes proliferative responses to mitogen or antigen. Furthermore, under different circumstances, SEB may have conflicting effects on the same T cells. While high concentrations (1–50 μg/ml) of SEB stimulate certain mouse T cell clones, low concentrations or trace levels havea potent suppressive effect on the same clones. The results indicate that the in vitro conflicting effects of SEB on the same T cells are concentration dependent and may reflect itsin vivo effects on SEB‐reactive T lymphocytes. The suppression of the mitogen‐ or antigen‐induced stimulation of T cell clones by SEB was direct and did not require the agency of suppressor cells. Furthermore, the suppression by low amounts of SEB was not major histocompatibility complex restricted and affected a largeproportion of both rat and mouse T lymphocyte subpopulations, regardless of their antigenic specificity. The concomitant suppressogenic and stimulatory characteristics of SEB support the conclusion that, under different conditions, SEB can be considered a “super‐suppressogen” as well as a “super‐antigen”. Overall, the results suggest that SEB, and possibly other bacterial toxins, could be useful in immunomodulation of specific T cell responses.