bluuebunny/crossref_metadata_2025_split huggingface dataset:
Major histocompatibility complex class I presentation of ovalbumin peptide 257–264 from exogenous sources: protein context influences the degree of TAP‐independent presentation
Authors: Wick Mary Jo , Pfeifer John D. 
Published: March 2007

AbstractPeritoneal macrophages from C57BL/6 mice process antigens from bacteria or coated on polystyrene beads for presentation by major histocompatibility complex (MHC) class I molecules. To investigate this antigen processing pathway, peritoneal macrophages from homozygous TAP1−/− mice, which lack the transporter associated with antigen processing (TAP) and are defective in presenting endogenous antigens on MHC class I, were used. TAP1−/− or C57BL/6 macrophages were co‐incubated with either bacteria or polystyrene beads containing the 257–264 epitope from ovalbumin [OVA(257–264)], which binds the mouse class I molecule Kb. The source of the OVA(257–264) epitope was either the Crl‐OVA(257–264) (Crl‐OVA) fusion protein, the maltose binding protein (MBP)‐Crl‐OVA fusion protein, native OVA or bacterial recombinant OVA (rOVA); Crl‐OVA, MBP‐Crl‐OVA and rOVA were each expressed in bacteria, and Crl‐OVA and MBP‐Crl‐OVA purified from bacterial lysates and native egg OVA were coated onto polystyrene beads. The data reveal that peritoneal macrophages from C57BL/6 and TAP1−/− mice can process bacteria expressing Crl‐OVA, MBP‐Crl‐OVA and rOVA as well as beads coated with native OVA, purified Crl‐OVA, and purified MBP‐Crl‐OVA and present OVA(257–264) for recognition by OVA(257–264)/Kb‐specific T hybridoma cells, albeit with different relative processing efficiencies. The processing efficiency of TAP1−/− macrophages co‐incubated with bacteria or beads containing Crl‐OVA or MBP‐Crl‐OVA was reduced approximately three to five times compared to C57BL/6 macrophages, but OVA(257–264) was presented 100 times less efficiently when the source of OVA(257–264) was full‐length OVA. Chloroquine inhibition studies showed a differential requirement for acidic compartments in C57BL/6 versus TAP1−/− macrophages, which also depended upon the source of the OVA (257–264) epitope (Crl‐OVA versus full‐length OVA). These data suggest that TAP1−/− and C57BL/6 macrophages may process Crl‐OVA and full‐length OVA in different cellular compartments and that the protein context of the OVA(257–264) epitope influences the extent of TAP‐independent processing for MHC class I presentation.
Protective immunization with plasmid DNA containing the outer surface lipoprotein A gene of Borrelia burgdorferi is independent of an eukaryotic promoter
Authors: Simon Markus M. , Gern Lise , Hauser Pierre , Zhong Weimin , Nielsen Peter J. , Kramer Michael D. , Brenner Christiane , Wallich Reinhard 
Published: March 2007

AbstractPlasmid DNA encoding the outer surface lipoprotein A (OspA) of Borrelia burgdorferi under the control of either strong eukaryotic/viral or its own bacterial promoter was injected intramuscularly (m. tibialis anterior) or intradermally into BALB/c and AKR/N mice. OspA‐specific antibodies and OspA‐reactive T helper 1 cells (Th1) were induced only with those plasmids containing the ospA structural gene including its own regulatory control region immediately upstream. In the absence of the ospA promoter, no or only marginal immune responses to OspA were obtained, even when strong eukaryotic promoter/enhancer elements were present. Together with the finding that the ospA promoter is active in a mouse B‐lymphoma line, the data suggest that spirochetes are able to express at least part of their genes in the mammalian environment. Mice previously vaccinated with the relevant ospA plasmid DNA were protected against subsequent experimental challenge with a virulent strain of B. burgdorferi, as measured by the appearance of antibodies to a prominent protective epitope (LA‐2) and the failure to re‐isolate spirochetes from ear biopsies. In addition, C.B‐17 severe‐combined immunodeficient mice could be protected against infection by passive transfer of immune sera from ospA plasmid DNA‐inoculated normal mice. Protective LA‐2‐related antibody titers obtained after repeated immunization persisted for 200 days and longer. This simple procedure of immunization using plasmid DNA consisting of a prokaryotic gene under the control of its own promoter holds great promise for the development of alternative subunit vaccines against bacterial infections, including Lyme disease. In addition, the availability of this novel prokaryotic promoter element now allows the study of the basis for the differential expression of bacterial genes in prokaryotic and eukaryotic environments.
The CD8β polypeptide is required for the recognition of an altered peptide ligand as an agonist
Authors: Renard Valéry , Delon Jérôme , Luescher Immanuel F. , Malissen Bernard , Vivier Eric , Trautmann Alain 
Published: March 2007

AbstractT cell activation is triggered by the specific recognition of cognate peptides presented by MHC molecules. Altered peptide ligands are analogs of cognate peptides which have a high affinity for MHC molecules. Some of them induce complete T cell responses, i.e. they act as agonists, whereas others behave as partial agonists or even as antagonists. Here, we analyzed both early (intracellular Ca2+ mobilization), and late (interleukin‐2 production) signal transduction events induced by a cognate peptide or a corresponding altered peptide ligand using T cell hybridomas expressing or not the CD8 α and β chains. With a video imaging system, we showed that the intracellular Ca2+ response to an altered peptide ligand induces the appearance of a characteristic sustained intracellular Ca2+ concentration gradient which can be detected shortly after T cell interaction with antigen‐presenting cells. We also provide evidence that the same altered peptide ligand can be seen either as an agonist or a partial agonist, depending on the presence of CD8β in the CD8 co‐receptor dimers expressed at the T cell surface.
A novel SP‐1 site in the human interleukin‐1β promoter confers preferential transcriptional activity in keratinocytes
Authors: Husmann Matthias , Jehnichen Petra , Jahn Bernhard , Schlosshan Dominik , Romahn Eric , Marx Jürgen 
Published: March 2007

AbstractTo investigate the mechanisms of transcriptional activation of interleukin‐1β (IL‐1β) in non‐monocytic cells, we constructed a series of reporter plasmids with the bacterial chloramphenicol acetyltransferase gene linked to various parts of the human IL‐1β promoter and performed transient transfection experiments. We identified a promoter segment that activates transcription most efficiently in keratinocytes. Electrophoretic mobility shift assays (EMSA) with a 43‐mer oligonucleotide derived from the functionally identified cis‐acting element revealed specific complexes. By competition analysis with transcription factor consensus sequence oligonucleotides and by immunosupershift, transcription factor SP‐1 or a closely related protein was shown to bind to this regulatory element. The closest match to the known SP‐1 consensus sequence within the respective region is a TCCCCTCCCCT motif. Mutation of this motif almost completely, and specifically, abolished the binding of two low‐mobility complexes and led to a 95% decrease of constitutive transcriptional activation of a reporter construct IL‐1β (− 170/+ 108). Likewise, activation of this reporter construct by tumor necrosis factor‐α depended on the SP‐1 site. These observations suggest that a so‐far‐unrecognized SP‐1 site in the human IL‐1β promoter may participate in the transcriptional regulation of this gene in keratinocytes.
Cytotoxic reactivity of gut lamina propria CD4+ αβ T cells in SCID mice with colitis
Authors: Bonhagen Kerstin , Thoma Stefan , Bland Paul , Bregenholt Søren , Rudolphi Angelika , Claesson Mogens H. , Reimann Jörg 
Published: March 2007

AbstractPolyclonal, mucosa‐seeking memory/effector CD4+ T cells containing a large fraction of blasts activated in situ accumulate in the gut lamina propria of severe‐combined immunodeficient (SCID) mice developing colitis after CD4+ T cell transplantation. CD4+ T cells isolated from different repopulated lymphoid tissues of transplanted SCID mice proliferate in vitro in the presence of interleukin (IL)‐2 + IL‐7. CD3 ligation enhances this cytokine‐supported proliferation in CD4+ T cells from the spleen and the mesenteric lymph node of transplanted SCID mice; CD3 ligation suppresses the cytokine‐supported proliferation in CD4+ T cells from the gut lamina propria in a cell density‐ and dose‐dependent manner. Almost all CD4+ T cells from repopulated lymphoid tissues of transplanted SCID mice express CD95 (Fas) on the cell surface, and a large fraction of CD4+ T cells from the gut lamina propria of transplanted SCID mice express the Fas ligand on the surface. Gut lamina propria CD4+ T cells show Fas‐dependent cytotoxicity. A large fraction of gut lamina propria CD4+ T cells that infiltrate the inflamed colon in transplanted SCID mice are activated in situ and many CD4+ T cells are apoptotic. Hence, a large fraction of colitis‐inducing CD4+ T cells undergo activation‐induced cell death in situ and can damage other cells through Fas‐dependent cytotoxicity.
Peripheral tolerance of CD4 T cells following local activation in adolescent mice
Authors: Förster Irmgard , Lieberam Ivo 
Published: March 2007

AbstractIn addition to thymic T cell selection, post‐thymic mechanisms of tolerance induction are required to eliminate autoreactive T cells with specificities for peripheral self antigens. While CD8+ T cells can recognize their target antigen on a wide variety of cell types, CD4+ T cells generally depend on the presence of specialized antigen‐presenting cells. Because of this fundamental difference in antigen recognition peripheral tolerance of CD4+ T cells appears more difficult to achieve than of CD8+ T cells. Utilizing T cell receptor (TCR)‐transgenic mice in which CD4+ T cells specific for a pancreatic β cell neoantigen (the simian virus 40 T antigen) are constantly generated at low frequency, we have now established a mouse model of peripheral, tissue‐specific CD4+ T cell tolerance. In these animals, tolerance is preceded by a phase of activation of the autoreactive T cells as characterized by up‐regulation of CD69 and CD44, and down‐regulation of the L‐selectin lymph node homing receptor. T antigen‐specific T cells bearing this phenotype can be detected in the local lymphoid environment of the pancreas but not in more remote locations like axillary or inguinal lymph nodes. The proportion of activated, autoreactive T cells is maximal at 2–3 weeks of age, after which these cells are gradually deleted from the peripheral lymphocyte pool. We further demonstrate that deletion of the autoreactive T cells does not occur in TCR‐tansgenic mice bred to the RAG‐1‐deficient background in which the transgenic T cells represent the only functional lymphocyte population.
T cell receptor α gene rearrangement and transcription in adult thymic γδ cells
Authors: Mertsching Elisabeth , Wilson Anne , MacDonald H. Robson , Ceredig Rhodri 
Published: March 2007

AbstractT cells belong to two separate lineages based on surface expression of αβ or γδ T cell receptors (TCR). Since during thymus development TCR β, γ, and δ genes rearrange before α genes, and γδ cells appear earlier than αβ cells, it has been assumed that αδ cells are devoid of TCR α rearrangements. We show here that this is not the case, since mature adult, but not fetal, thymic γδ cells undergo VJα rearrangements more frequently than immature αβ lineage thymic precursors. Sequence analysis shows VJα rearrangements in γδ cells to be mostly (70 %) nonproductive. Furthermore, VJα rearrangements in γδ cells are transcribed normally and, as shown by analysis of TCR β‐/‐ mice, occur independently of productive VDJβ rearrangements. These data are interpreted in the context of a model in which precursors of αβ and γδ cells differ in their ability to express a functional pre‐TCR complex.
The intensity of T cell receptor engagement determines the cytokine pattern of human allergen‐specific T helper cells
Authors: Carballido José M. , Faith Alexander , Carballido‐Perrig Nicole , Blaser Kurt 
Published: March 2007

AbstractEnhanced production of T helper (Th)2 cytokines by allergen‐specific Th cells plays a major role in the induction and maintenance of IgE‐mediated allergic disorders. The mechanism that triggers this type of response in atopic individuals is not fully understood. Allergen‐specific human Th cell clones produce interleu‐kin (IL)‐4 and low or undetectable levels of interferon (IFN)‐γ after stimulation with low concentrations of antigen. However, these Th cell clones are capable of generating significant amounts of IFN‐γ after optimal activation through their T cell receptor (TcR). Allergen‐specific Th cell clones isolated from allergic individuals required higher doses of antigen to reach the plateau of proliferation and to generate Th0 cytokine responses than their counterparts isolated from nonal‐lergic subjects. On the other hand, if allergen was replaced by anti‐CD3 monoclonal antibody (mAb), both allergic and nonallergic Th cell clones attained the highest level of proliferation and significant IFN‐γ production in response to equivalent concentrations of anti‐CD3 mAb. These results indicate that the strength of T cell ligation, which can be modulated by the availability of the TcR ligand, controls the balance of Th1/Th2 cytokines produced by memory Th cells in vitro. In the particular case of bee venom phospholipase A2, it is shown that the expression of allergen‐specific surface Ig on antigen‐presenting B cells has little influence on antigen uptake and therefore in determining the levels of T cell activation and cytokine production. Alternatively, the affinity of particular major histocompatibility complex class II molecules on antigen‐presenting cells for allergen‐derived peptides might determine the amount of specific ligand presented to the Th cells and play a decisive role skewing the Th cell cytokine production towards Th1 or Th2 phenotypes. These findings, which are consistent with the changes in cytokine patterns observed following clinical hyposensitization, suggest that polarized human Th2 cell subsets still retain the capacity to modulate their cytokine pattern.
Immune modulation with interleukin‐4 and interleukin‐10 prevents crescent formation and glomerular injury in experimental glomerulonephritis
Authors: Tipping Peter G. , Kitching A. Richard , Huang Xiao Ru , Mutch David A. , Holdsworth Stephen R. 
Published: March 2007

AbstractCrescentic glomerulonephritis (GN) demonstrates immunopathological features of a T helper (Th)1‐directed delayed‐type hypersensitivity (DTH) response. The capacity of Th2 cytokines to attenuate crescentic glomerular injury in this disease was examined by administering interleukin (IL)‐4 and IL‐10, singly and in combination. GN was induced by i.v. administration of sheep anti‐mouse glomerular basement membrane (GBM) globulin to mice sensitized to sheep globulin 10 days earlier. Treatment (2.5 μg, i.p.) with IL‐4, IL‐10, or both IL‐4 and IL‐10 (IL‐4+10), was started 1 h before sensitization and continued daily until the end of the study (10 days after administration of anti‐GBM globulin). Control mice treated with PBS developed GN with glomerular accumulation of T cells and macrophages, crescents in 42.5 ± 4.5 % of glomeruli (normal 0 %), proteinuria (8.3 ± 0.9 mg/24 h, normal 0.74 ± 0.08 mg/24 h, p < 0.001) and renal impairment (creatinine clearance [cr/cl]: 93 ± 12 μ1/min, normal 193 ± 10 μ1/min, p<0.001). 1reatment with either IL‐4, IL‐10, or IL‐4+10 prevented crescent formation (crescentic glomeruli: 0.8 ± 0.5, 1.2 ± 0.9, and 1.4 ± 1.0 %, respectively, all p<0.01 compared to control) and attenuated proteinuria (3.6 ± 1.0, 2.2 ± 0.5, and 2.9 ± 0.5 mg/24 h, respectively, all p<0.01 compared to control). IL‐4+10 prevented development of renal impairment (cr/cl: 183 ± 22 μ1/min); IL‐10 given alone limited the decline in renal function (cr/cl: 150 ± 20 μ1/min), but IL‐4 alone did not provide any significant protection (cr/cl: 121 ± 17 μ1/min). All treatments markedly diminished glomerular T cell and macrophage accumulation, reduced interferon‐γ production by splenic T cells, prevented cutaneous DTH to the disease‐initiating antigen and reduced antigen‐specific immunoglobulin of the IgG2a and IgG3 isotypes. These data demonstrate that crescentic GN and renal impairment can be prevented by administration of Th2 cytokines and that this effect is associated with attenuation of the Th1 response to the disease‐initiating antigen.
Cleavage of the low‐affinity receptor for human IgE (CD23) by a mite cysteine protease: Nature of the cleaved fragment in relation to the structure and function of CD23
Authors: Schulz Oliver , Sutton Brian J. , Beavil Rebecca L. , Shi Jianguo , Sewell Herb F. , Gould Hannah J. , Laing Peter , Shakib Farouk 
Published: March 2007

AbstractDer p I, a cysteine protease representing a major allergen of the house dust mite Dermatophagoides pteronyssinus, has recently been shown to cleave CD23 from the surface of cultured human B cells (RPMI 8866 B cell line). We have now undertaken a detailed investigation of CD23 cleavage by Der p I. We demonstrate that Der p I cleaves CD23 at two sites (Ser155‐Ser156 and Glu298‐Ser299) to produce a 17‐kDa fragment containing the lectin domain and only part of the C‐terminal tail. No such effect was demonstrable with mouse CD23, a finding which was anticipated based on its lack of the cleavage sites identified on human CD23. Based on the cleavage pattern and the model of CD23, we propose a sequence of events leading to the liberation of the 17‐kDa soluble CD23 fragment. The biological significance of such cleavage is underlined by the demonstration that Der p I‐treated B lymphocytes lose their ability to bind IgE, and that the 17‐kDa fragment (amino acids 156–298) contains the minimum structural requirement (amino acids 156–288) for binding to both IgE and CD21.
Antigen‐presenting cells pulsed with unfractionated tumor‐derived peptides are potent tumor vaccines
Authors: Nair Smita K. , Boczkowski David , Snyder David , Gilboa Eli 
Published: March 2007

AbstractVaccination with peptides isolated from tumor cells circumvents the need for identifying specific tumor rejection antigens and extends the use of active immunotherapy to the majority of cancers where specific tumor antigens have not yet been identified. In this study, we examined the efficacy of tumor vaccines composed of unfractionated tumor peptides presented by antigen‐presenting cells (APC) to induce cytotoxic T lymphocyte (CTL) responses and tumor immunity. RMA‐S cells pulsed with peptides isolated from ovalbumin (OVA)‐expressing tumor cells were highly effective at inducing primary, OVA‐specific CTL responses in vitro and priming CTL responses in vivo. In addition, tumor peptide‐pulsed RMA‐S cells induced protective immunity in mice when challenged with OVA‐expressing tumor cells. To enhance the clinical relevance of these studies, cells pulsed with tumor peptides were evaluated in the poorly immunogenic, B16/F10.9 melanoma post‐surgical metastasis model. Treatment of tumor‐bearing mice with peptide‐pulsed RMA‐S cells or with adherent splenocytes (enriched for professional APC) caused a significant reduction in lung metastases. The antimetastatic effect of peptide‐pulsed splenocytes could be further enhanced by pretreating the cells with antisense oligonucleotides directed against the TAP‐2 gene which was previously shown to increase the density of specific peptide/MHC class I complexes and thereby improve the APC function of the treated cells (Nair et el., J. Immunol. 1996. 156: 1772). This study suggests that APC loaded with unfractionated peptides derived from poorly immunogenic, highly metastatic tumor cells may represent a potent form of tumor vaccine.
Cloning of novel immunoglobulin superfamily receptors expressed on human myeloid and lymphoid cells: Structural evidence for new stimulatory and inhibitory pathways
Authors: Samaridis Jacqueline , Colonna Marco 
Published: March 2007

AbstractWe have identified two novel human cDNA encoding transmembrane proteins of the immunoglobulin superfamily (IgSF). The two cDNA, called immunoglobulin‐like transcripts 1 and 2 (ILT1 and ILT2), are expressed in myeloid and lymphoid cells and are homologous to bovine Fcγ2R, human killer cell inhibitory receptors (KIR), human FcαR, and mouse gp49. Furthermore, ILT1 and ILT2 are encoded on chromosome 19, as are FcαR and KIR. While the ILT1 and ILT2 extracellular domains are homologous, the transmembrane and cytoplasmic domains differ substantially. ILT1 has an arginine within the transmembrane region, followed by a short cytoplasmic tail, similar to human FcαRI and bovine Fcγ2R. ILT2 has a long cytoplasmic tail, which contains two YxxV and two YxxL pairs similar to the immunoreceptor tyrosine‐based inhibitory motifs in KIR that are known to bind the phosphotyrosine phosphatase SHP‐1. These cytoplasmic features suggest that ILT1 and ILT2 may mediate novel transmembrane signals by which myeloid and lymphoid cell responses can be either activated or inhibited.
Interferon‐γ is essential for the development of cerebral malaria
Authors: Rudin Werner , Favre Nicolas , Bordmann Gérard , Ryffel Bernhard 
Published: March 2007

AbstractInfection with Plasmodium berghei ANKA (PbA) causes fatal cerebral malaria (CM). While a pathogenic role for tumor necrosis factor (TNF) has been established, we asked whether a disruption of interferon‐γ (IFN‐γ) signaling would modulate CM. We demonstrate here that IFN‐γR‐deficient mice are completely protected from CM. PbA‐induced release of TNF and up‐regulation of endothelial intercellular adhesion molecule (ICAM)‐1 expression, recruitment of mononuclear cells, and cerebral microvascular damage with vascular leakage occur only in wild‐type mice. Protected mice die at a later time of severe anemia and overwhelming parasitemia. Resistance to CM in IFN‐γR‐deficient mice is associated with reduced serum TNF levels, reduced interleukin‐12 expression in the brain and increased T‐helper 2 cytokines. In conclusion, IFN‐γ is apparently required for PbA‐induced endothelial ICAM‐1 up‐regulation and subsequent microvascular pathology, resulting in fatal CM. In the absence of IFN‐γ signaling, ICAM‐1 and TNF up‐regulation is reduced; hence, PbA infection fails to cause fatal CM.
Selective down‐regulation of Th2 immune responses following treatment with antigen‐coupled splenocytes
Authors: Soldera Sylvelie , McSorley Stephen J. , Glaichenhaus Nicolas 
Published: March 2007

AbstractIntravenous injection of antigen‐coupled splenocytes has been widely used to induce specific tolerance to a variety of antigens. In this study, we investigated the effects of such a treatment on Th1 and Th2 antigen‐specific immune responses. Using both well‐characterized model antigens and crude homogenates from Leishmania major promastigotes, we found that intravenous injection of antigen‐coupled splenocytes strongly down‐regulated antigen‐specific Th2 responses but had no or only moderate effects on Th1 responses. Because the susceptibility of inbred strains of mice to murine leishmaniasis has been found to be correlated with a strong Th2 response against parasite antigens, we investigated whether administration of splenocytes chemically coupled to parasite antigens could protect susceptible mice from murine leishmaniasis. We found that this was indeed the case and further demonstrated that protection was associated with a strong decrease in the number of parasite‐specific Th2‐like cells. Because administration of antigen‐coupled splenocytes is believed to induce ligation of the T cell receptor complex without inducing a co‐stimulatory signal, our results further suggest that priming of Th1 cells is less dependent on co‐stimulatory signals than the priming of Th2 cells.