bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of glycosylphosphatidylinositol‐linked H‐2Dd molecules on target cell protection and natural killer cell specificity in transgenic mice
Authors: Sentman Charles L. , Olsson‐Alheim Mats Y. , Lendahl Urban , Kärre Klas 
Published: March 2007

AbstractThe expression of certain major histocompatibility complex (MHC) class I ligands on target cells is one important determinate of their susceptibility to lysis by natural killer (NK) cells. NK cells express receptor molecules that bind to MHC class I. Upon binding to their MHC class I ligand, the NK cell is presumed to receive a signal through its receptor that inhibits lysis. It is unclear what role the MHC class I molecules of the effector and target cells play in signaling to the NK cell. We have investigated the role of the cytoplasmic and transmembrane domains of MHC class I molecules by producing a glycosylphosphatidylinositol (GPI)‐linked H‐2Dd molecule. The GPI‐linked H‐2Dd molecule is recognized by H‐2Dd‐specific antibodies and cytotoxic T lymphocytes. Expression of the GPI‐linked H‐2Dd molecule on H‐2b tumor cells resulted in protection of the tumor cells after transplantation into D8 mice (H‐2b, H‐2Dd) from rejection by NK cells. In addition, NK cells from mice expressing the GPI‐linked H‐2Dd molecule as a transgene were able to kill nontransgenic H‐2b lymphoblast target cells. The GPI‐linked MHC class I molecule was able to alter NK cell specificity at the target and effector cell levels. Thus, the expression of the cytoplasmic and transmembrane domains of MHC class I molecules are not necessary for protection and alteration of NK cell specificity.
R24 anti‐GD3 ganglioside antibody can induce co‐stimulation and prevent the induction of alloantigen‐specific T cell clonal anergy
Authors: Boussiotis Vassiliki A. , Pardo Nichole A. , Collins Heather , Houghton Alan , Ritz Jerome , Nadler Lee M. , Soiffer Robert J. 
Published: March 2007

AbstractR24 is a monoclonal antibody directed against the cell surface ganglioside GD3. It can detect GD3 on the surface of a subset of T lymphocytes and can stimulate proliferation and secretion of cytokines in vitro. In the present report, we examined the effects of the R24 antibody upon antigen‐specific T cell response, employing an HLA‐DR7‐specific T cell clonal model. As previously shown, primary stimulation of HLA‐DR7‐specific alloreactive T cell clones by transfectants expressing HLA‐DR7 alone (t‐DR7) in the absence of B7 co‐stimulation resulted in anergy. Binding of cell surface GD3 on HLA‐DR7‐specific alloreactive T cell clones with R24 under these anergizing conditions resulted in interleukin‐2 (IL‐2) accumulation and prevented the induction of alloantigen‐specific T cell clonal anergy. Binding of GD3 by R24 also prevented anergy under conditions where B7:CD28 interactions were blocked by CTLA4‐Ig. The effect of R24 was abrogated in the presence of a combination of monoclonal antibodies for the α and β chains of the IL‐2 receptor (IL‐2R) or a neutralizing anti‐IL‐2 antibody. R24 does not appear to interact directly with the IL‐2R since incubation of T cell clones with R24 did not induce early activation of IL‐2R associated Jak kinases, Jak1 and Jak3, as was induced following incubation with IL‐2. In contrast, incubation of HLA‐DR7‐specific clones with t‐DR7 in the presence of R24 did result in phosphorylation of IL‐2R related Jak kinases after 24 h. Our data indicate that the membrane ganglioside GD3 structure recognized by R24 may play an important role in antigen‐specific T cell clonal response.
Rapid induction of tumor necrosis factor cytotoxicity in naive splenic T cells by simultaneous CD80 (B7.1) and CD54 (ICAM‐1) co‐stimulation
Authors: Nishio Makoto , Podack Eckhard R. 
Published: March 2007

AbstractThe co‐expression of B7.1 (CD80) and intercellular adhesion molecule (ICAM)‐1 (CD54) on tumor cells can induce tumor immunity and immunological memory. We show here that the non‐immunogenic tumor lines Lewis lung carcinoma and B16F10 melanoma, co‐transfected with B7.1 and ICAM‐1, induced cytotoxic levels of membrane tumor necrosis factor (TNF) on naive syngeneic T cells within 24 h. Membrane TNF expression, primarily on CD4 cells, was responsible for tumor cell lysis by naive spleen cells and could be completely abolished by anti‐TNF antiserum. It is suggested that the strong induction of TNF cytotoxicity may be important in the establishment of tumor immunity.
The expression of cytokine‐induced neutrophil chemoattractants (CINC‐1 and CINC‐2) in rat peritoneal macrophages is triggered by Fcγ receptor activation: Study of the signaling mechanism
Authors: Alonso Adrés , Bayón Yolanda , Crespo Mariano Sánchez 
Published: March 2007

AbstractThe expression of cytokine‐induced neutrophil chemoattractants (CINC‐1 and CINC‐2) mRNA was studied in rat peritoneal cells stimulated with insoluble IgG/ovalbumin immune complexes. A dose‐ and time‐dependent induction was observed in adherent cells, which was more prominent than that induced by the lipid mediator platelet‐activating factor (PAF), comparable to that observed in response to 10 μg endotoxin in the absence of lipopolysaccharide (LPS)‐binding protein, but lower than that produced by 1 mM dibutyryl cyclic AMP, a compound which stabilizes transiently expressed genes containing AU‐rich sequences in the 3′ untranslated region. Analysis of CINC‐1 protein by specific enzyme‐linked immunosorbent assay confirmed the presence of CINC‐1 in the supernatants at concentrations of ∼4 nM, 4 h after addition of 100 μg/ml immune complexes. CINC‐2β protein was detectable at a lower concentration (∼0.3 nM) under the same conditions. Attempts to relate CINC‐1 induction with the pathways for cytoplasmic signaling showed a dissociation of Ca2+ mobilization and protein kinase C activation as judged from the small effect of thapsigargin and the lack of effect of phorbol ester. In contrast, these agents produced a marked mobilization of arachidonate linked to the MAP kinase‐dependent activation of cytosolic phospholipase A2. The possible dependence of CINC‐1 induction on the autocrine generation of lipid mediators was ruled out by a set of experiments including the use of the PAF receptor antagonist BB823, and the analysis of the effect of free arachidonate and leukotriene B4 on CINC‐1 induction. Surprisingly, the inhibitor of leukotriene synthesis MK‐886 in the range of concentration 1–10 μM inhibited CINC‐1 induction by a mechanism that appears to be independent of its effect on eicosanoid production. Interestingly, CINC‐1 induction appeared to be related to protein tyrosine phosphorylation reactions on the basis of both the appearance of several tyrosine‐phosphorylated protein bands in lysates from adherent peritoneal cells treated with immune complexes and the complete blockade of CINC‐1 induction by treatment with 1 μM herbimycin A, an inhibitor of src protein tyrosine kinases.
Functionally distinct T cells in three compartments of the respiratory tract after influenza virus infection
Authors: Baumgarth Nicole , Kelso Anne 
Published: March 2007

AbstractThis study aimed to resolve, firstly, whether T cell responses induced in one tissue site are similar to those induced by the same antigen in another site and, secondly, whether influenza virus infection induces one predominant type of T cell response locally in the respiratory tract. To address these questions, T cell responses in three compartments of the respiratory tract were compared after infection of mice with a sublethal dose of influenza virus: the draining mediastinal lymph nodes (MLN), the lung parenchyma and the airways. Each compartment harbored a T cell response substantially different from that found at the other sites. A preferential accumulation of ex vivo‐cytolytic CD8+ T cells was found in the airways (CD4/CD8 ratio 1:2) and to a lesser extent in the lung parenchyma (CD4/CD8 ratio 1:1). T cells from both compartments expressed high levels of various cytokine mRNA, but showed differences in their respective expression pattern, with those from lung tissue showing particularly high levels of IFN‐γ mRNA. The response in the draining lymph nodes, on the other hand, was dominated by CD4+ T cells (CD4/CD8 ratio 2:1) with a higher proliferative capacity (after TCR/CD3 cross‐linking) and which provided better B cell help in vitro than CD4+ T cells isolated from lung tissue. T cells from MLN expressed mRNA for a variety of cytokines with only low levels of IFN‐γ mRNA and they showed no CTL activity ex vivo. These functional differences were not due to differences in the kinetics of the response, or to the higher frequencies of activated T cells in lung tissue and airways compared to MLN, since the differences remained when cell‐sorter‐purified activated (CD18hi, CD44hi) T cells from MLN and lung tissue were compared in a time‐course study. Taken together, these findings indicate that pathogens such as influenza virus induce a heterogenous set of T cell responses in different tissue sites affected by the infection.
Glycosylphosphatidylinositol‐anchored H‐2Db molecules are defective in antigen processing and presentation to cytotoxic T lymphocytes
Authors: Cariappa Annaiah , Flyer David C. , Rollins Carl T. , Roopenian Derry C. , Flavell Richard A. , Brown Dennis , Waneck Gerald L. 
Published: March 2007

AbstractGlycosylphosphatidylinositol‐anchored (GPI)‐Db molecules are defective in mediating cytotoxic T lymphocytes (CTL) lysis of transfected lymphoma cells, compared to their transmembrane (TM) counterpart. This defect is manifest when antigenic peptide must be processed and presented through the endogenous pathway. These same transfectants can be lysed by allospecific CTL, or by antigen‐specific Db‐restricted CTL when pulsed with appropriate exogenous synthetic peptide, demonstrating that they can bind and present peptide for CTL‐mediated lympholysis. The defect apparently results from differences between GPI‐Db and TM‐Db assembly and transport, or from differences in membrane topology that affect CD8+ CTL recognition of major histocompatibility complex/peptide complex.
Differences in Vϰ gene utilization and VH CDR3 sequence among anti‐DNA from C3H‐lpr mice and lupus mice with nephritis
Authors: Wloch Mary Kopke , Alexander Audrey L. , Pippen Anne M. M. , Pisetsky David S. , Gilkeson Gary S. 
Published: March 2007

AbstractTo investigate the molecular properties of anti‐DNA from lpr mice that express high levels of anti‐DNA without immune‐mediated nephritis, the sequences of VH and Vϰ genes encoding 11 monoclonal anti‐DNA antibodies derived from C3H‐lpr/lpr (C3H‐lpr) mice were studied. All of the C3H‐lpr monoclonal anti‐DNA bound single‐stranded DNA while five also bound double‐stranded DNA. Two of the hybridomas were clonally related as determined by Southern analysis and sequencing. Sequence analysis of C3H‐lpr anti‐DNA revealed the use of VH genes that encode anti‐DNA from the MRL‐lpr/lpr and (NZB X NZW)F1 mouse models of lupus, although differences occurred in the VH CDR3 amino acid content. In contrast, the Vϰ genes from C3H‐lpr mice lacked significant identity with previously reported Vϰ genes for anti‐DNA from lupus models. These results indicate that anti‐DNA from C3H‐lpr mice differ from anti‐DNA from lupus mice with nephritis in patterns of V gene expression and suggest a molecular basis for the lack of pathogenicity of anti‐DNA in these mice.
Differential activation of T cell cytokine production by the extracellular signal‐regulated kinase (ERK) signaling pathway
Authors: Egerton Mark , Fitzpatrick David R. , Catling Andrew D. , Kelso Anne 
Published: March 2007

AbstractStimulation of T cells via the T cell receptor (TCR) activates a number of signaling pathways that are potentially involved in the elicitation of physiological responses, such as the production of cytokines. The extracellular signal‐regulated kinases (ERK) are a group of molecules activated in response to TCR ligation, whose role in T cell cytokine production is controversial. In this study, we have asked whether ERK activation is coupled to the production of a number of T cell‐derived cytokines, and whether particular cytokines are differentially affected by ERK activation. To address these questions, we have utilized a constitutively active version of the immediate upstream activator of both ERK1 and ERK2, mitogen‐activated/extracellular signal‐regulated kinase 1 (MEK1), to activate ERK signaling selectively in the absence of other TCR‐activated signaling pathways. The effect of constitutive MEK/ERK activation on T cell cytokine production was measured by transiently co‐transfecting newly activated mouse T cells with DNA encoding constitutively active MEK1 (CA‐MEK1) and the human interleukin‐2 (IL‐2) receptor α chain (hCD25), purifying hCD25+ transfectants by flow‐cytometric cell sorting, and measuring the production of IL‐3, IL‐4, interferon (IFN)‐γ and granulocyte/macrophage‐colony‐stimulating factor (GM‐CSF) either in the presence or absence of ionomycin stimulation. Newly activated T cells were used in these experiments as they more closely resemble T cells activated in vivo than do transformed T cells or long‐term established T cell clones. CA‐MEK1 expression led to constitutive ERK activation, which acted synergystically with ionomycin treatment to stimulate cytokine production. Furthermore, these experiments revealed a hierarchy of cytokine responsiveness to MEK/ERK activation, such that the production of IL‐3 was most affected, followed by GM‐CSF, IFN‐γ, and IL‐4.
Noncovalent associations of T lymphocyte surface proteins
Authors: Černý Jan , Stockinger Hannes , Hořejší Václav 
Published: March 2007

AbstractA number of T cell surface transmembrane molecules such as CD2, CD4, CD8, lymphocyte functional antigen (LFA)‐1 and CD45 are known to interact functionally with the T cell receptor (TCR) complex during T cell activation. Several previous communications have also reported physical associations between some of these molecules. On the other hand, there are indications that signaling through T cell surface molecules anchored via glycosylphosphatidylinositol (GPI), such as Thy‐1, Ly‐6 or CD59, is dependent on the TCR. Therefore, it was of interest to determine in a systematic way which T cell surface molecules are noncovalently associated with the TCR/CD3 complex and with the major intracellular signaling molecules, the protein tyrosine kinases of the Src family. To this aim, membrane proteins of human thymoma HPB‐ALL cells were solubilized in a solution of the mild detergent Brij‐58 and subjected to immunoprecipitation followed by in vitro kinase assays. Two types of large complexes containing protein tyrosine kinases were observed: the first one contained CD3 and the transmembrane proteins CD2, CD4, CD5, CD6, CD7, CD8, CD11a, CD38, CD43, CD45, CD71, CD98 and CD99 and the other contained mainly the GPI‐anchored proteins CD48, CD55, CD59 and CDw108 as well as a fraction of CD4 and CD8. The GPI‐anchored protein complexes were of larger size and lower buoyant density than the CD3 complexes. In agreement with these biochemical data, co‐cross‐linking of CD3 with most of the relevant transmembrane proteins on the surface of another T cell line, Jurkat, markedly enhanced tyrosine phosphorylation of several intracellular proteins. These data indicate the existence of at least two types of membrane microdomains of very different composition in the membranes of T cells which may play a role in signaling through different types of receptors and in functional cooperation between TCR/CD3 and various accessory molecules.
Differential effects of transforming growth factor‐β1 on IgA vs. IgG2b production by lipopolysaccharide‐stimulated lymph node B cells: a comparative study with spleen B cells
Authors: García Belén , Rodríguez Rosa , Angulo Iñigo , Heath Andrew W. , Howard Maureen C. , Subiza José L. 
Published: March 2007

AbstractTransforming growth factor‐β1 (TGF‐β1) is a multifunctional cytokine that promotes IgA/IgG2b switching and secretion. Here, we show a differential effect of TGF‐β1 on Ig production by lipopolysaccharide‐stimulated spleen and lymph node (LN) B cells. Exogenous TGF‐β1 increased IgA production in B cell cultures and IgG2b production by spleen B cells. In contrast, IgG2b was suppressed by TGF‐β1 in cultures of LN B cells, although endogenous TGF‐β was required for IgG2b production in LN B cell cultures. The suppressor properties of exogenous TGF‐β1 (0.5 ng/ml) on IgG2b production by LN B cells were also seen when testing IgG1 or IgG2a induced by interleukin‐4 or interferon‐γ, respectively. These differences between B cells from each lymphoid tissue appeared to be related to a different TGF‐β antiproliferative effect, since proliferation of LN B cells was extremely sensitive to TGF‐β1 and IgG2b production was more sensitive than IgA to the TGF‐β‐mediated suppression. However, by counteracting the antiproliferative effect of TGF‐β1 with a CD40 agonistic mAb (IC10), the IgG2b response by LN B cells was still lacking. IC10 was nevertheless inhibitory for IgG2b production in most cases, while increasing secretion of IgA in the very same cultures. Taken together, the results suggest that functional differences between spleen and LN B cells do exist, at least with regard to the immunomodulating properties of TGF‐β on both proliferation and Ig production. Moreover, functional differences exist between cells committed for IgA and IgG2b regarding their sensitivity to the antiproliferative activity of TGF‐β1 and the effect of CD40‐derived signals on Ig secretion.
Mapping of the domains required for decay acceleration activity of the human factor H‐like protein 1 and factor H
Authors: Kühn Sabine , Zipfel Peter F. 
Published: March 2007

AbstractThe human factor H‐like protein 1 (FHL‐1) is composed of seven repetitive elements (short consensus repeats; SCR) that are identical in sequence to the seven N‐terminal SCR of complement factor H. We show that the FHL‐1 protein has decay acceleration activity in that it can dissociate C3/C5‐convertases bound to the surface of sheep red blood cells. The same activity was also determined for factor H. However, compared to FHL‐1, factor H was more efficient in decay acceleration, as about 100‐fold less protein was required for a 50% inhibition of activity. The domain required for decay accelerating activity of FHL‐1 and factor H was mapped by the use of recombinant fragments. FHL‐1 and a series of truncated forms of the protein were expressed in the baculovirus system. Recombinant FHL‐1 and all mutants which include SCR 1–4 were functionally active. These four N‐terminal SCR are essential and sufficient for activity, as deletion mutants which lack SCR 1 or SCR 4 showed no activity. These results demonstrate that FHL‐1 and factor H have identical and overlapping regulatory functions in the complement system and that the domain required for this activity is located in the overlapping region of both proteins within the N‐terminal four SCR.
Expression and cleavage of tumor necrosis factor‐α and tumor necrosis factor receptors by human monocytic cell lines upon direct contact with stimulated T cells
Authors: Vey Elisabeth , Burger Danielle , Dayer Jean‐Michel 
Published: March 2007

AbstractTumor necrosis factor‐α (TNF‐α) is a potent cytokine in inflammatory processes. A variety of mechanisms that modulate its activity have been described, one being its binding to soluble receptors (sTNFR). In this study, we demonstrate that human monocytic cells such as THP‐1 respond to direct contact with a membrane preparation of stimulated HUT‐78 cells by producing TNF‐α and by releasing sTNFR‐p75, but not sTNFR‐p55, with different kinetics. TNF‐α concentration peaked after 12 h of contact and then decreased, whereas sTNFR‐p75 production increased progressively upon cell/cell contact. The decrease in TNF‐α concentration is not due to trapping of TNF‐α by its soluble receptors or other soluble or cell‐associated molecules, but rather to a proteolytic activity associated to THP‐1 cells. On the other hand, the increase in sTNFR‐p75 release does not result from an increase in the cleavage of pre‐existing cell‐associated sTNFR‐p75 but from an increase in TNFR‐p75 expression, immediately followed by the cleavage of its extracellular domain. Phenylmethylsulfonylfluoride, a serine protease inhibitor, has a negative effect on both TNF‐α degradation and sTNFR‐p75 release by THP‐1 cells. Thus, there may be an enzymatic activity associated to THP‐1 cells that plays an important role in the neutralization of TNF‐α activity both by degrading the molecule and by cleaving its receptors at the cell surface.
Differential modulation of cyclin‐dependent kinase inhibitor p27Kip1 by negative signaling via the antigen receptor of B cells and positive signaling via CD40
Authors: Han Hua , Nomura Takashi , Honjo Tasuku , Tsubata Takeshi 
Published: March 2007

AbstractThe cross‐linking of surface immunoglobulins (sIg) of B cells can transmit a negative signal, resulting in cell cycle arrest, apoptosis or both. Signaling via the B cell antigen CD40 reverses the sIg‐mediated negative signaling and induces activation and proliferation of B cells. We investigated the molecular mechanisms for cell cycle regulation by negative and positive signaling via sIg and CD40, respectively, by using the B cell line WEHI‐231. Cross‐linking of sIg almost completely reduced the activity of cyclin‐dependent kinase (Cdk) 2, essential for cell cycle progression in the late G1 phase, although the level of Cdk2 was not reduced. Among the factors that regulate Cdk2 activation, the activity of the Cdk‐activating kinase (CAK) appeared intact and cyclin E was reduced only partially in sIg‐cross‐linked WEHI‐231. In contrast, sIg cross‐linking induced a significant Cdk inhibitor (CKI) activity. Since a 27‐kDa protein was co‐precipitated with Cdk2 in anti‐Ig‐treated, but not untreated WEHI‐231, and the CKI activity in anti‐Ig‐treated WEHI‐231 was neutralized by anti‐p27Kip1, antibodies, it is most likely that p27Kip1 is responsible for the CKI activity induced by sIg cross‐linking. p27Kip1 may thus play a role in growth inhibition of B cells by negative signaling via sIg. In contrast, CD40 signaling enhanced Cdk2 activity and reduced the p27Kip1 level in anti‐Ig‐treated WEHI‐231, suggesting that the reduction of p27Kip1 plays an important role in the abrogation of sIg‐mediated growth arrest by CD40 signaling. Taken together, p27Kip1 is likely to be a crucial target molecule of the negative signaling via sIg and the positive signaling via CD40 essential for T cell‐dependent immune responses.
Biological properties of recombinant chicken interferon‐γ
Authors: Weining Kirsten C. , Schultz Ursula , Münster Uwe , Kaspers Bernd , Staeheli Peter 
Published: March 2007

AbstractSupernatants of the chicken T cell line 855 contain antiviral and macrophage‐activating factor activity and strongly activate transcription of the guanylate‐binding protein (GBP) gene in chicken cells. To characterize the cytokine responsible for the GBP‐inducing activity, we chose a cDNA expression cloning strategy in COS cells. Sequencing a positive clone revealed that it encodes chicken interferon‐γ (ChIFN‐γ). Histidine‐tagged ChIFN‐γ was expressed in Escherichia coli and purified by nickel chelate affinity chromatography. ChIFN‐γ from COS cells and E. coli both potently induced GBP RNA synthesis but were rather poor antiviral agents. In macrophages, recombinant ChIFN‐γ strongly stimulated secretion of nitric oxide and enhanced expression of major histocompatibility complex class II antigen. A rabbit antiserum to E. coli‐derived ChIFN‐γ effectively neutralized the macrophage‐activating factor activity secreted by concanavalin A‐induced spleen cells and various T cell lines, suggesting that IFN‐γ is the major macrophage‐activating factor of the chicken.