bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glycoinositolphospholipids of Leishmania major inhibit nitric oxide synthesis and reduce leishmanicidal activity in murine macrophages
Authors: Proudfoot Lorna , O'Donnell Catherine A. , Liew Foo Y. 
Published: March 2007

AbstractMurine macrophages express high levels of inducible nitric oxide (NO) synthase and produce large amounts of nitric oxide when activated with interferon‐γ and lipopolysaccharide in vitro. Nitric oxide is a mediator of a variety of biological functions including microbicidal activity against the protozoan parasite Leishmania species. Glycoinositolphospholipids (GIPL) are the predominant surface glycolipids in both developmental stages of Leishmania major. We report here that GIPL can inhibit the synthesis of NO in a time‐ and dose‐dependent manner. In contrast, lipophosphoglycan, which is present in the promastigote stage did not inhibit NO synthesis. GIPL‐treated macrophages also showed markedly reduced leishmanicidal activity. The majority of the inhibitory activity of GIPL was found within the alkylacylglycerol moiety of the GIPL molecule. These data, therefore, suggest that GIPL may contribute towards the survival of the parasite in the immune hosts.
Major histocompatibility complex class I‐restricted presentation of influenza virus nucleoprotein peptide by B lymphoma cells harboring an antibody gene antigenized with the virus peptide
Authors: Billetta Rosario , Filaci Gilberto , Zanetti Maurizio 
Published: March 2007

AbstractWe analyzed the capacity of B cells to process and present a peptide from the variable region of an endogenous immunoglobulin heavy (H) chain to a major histocompatibility complex (MHC) class I‐restricted cytotoxic T lymphocyte (CTL) clone. The H‐chain gene was engineered to express 14‐amino acid peptide from the sequence of the influenza virus nucleoprotein (NP) antigen in the third complementarity‐determining region (CDR3). This NP peptide is presented in association with the Db allele in H−2b mice. We demonstrate that B lymphoma cells (H‐2b) harboring the antigenized H‐chain gene process and present the NP peptide in association with the Db molecule and are lysed by a CTL clone specific for that peptide in an MHC‐restricted way. In contrast, the soluble antigenized antibody failed to mediate lysis of H−2b target cells. The endogenously processed immunoglobulin CDR3 peptide could be eluted from surface Db molecules in transfected cells. This study formally demonstrates that peptides from the hypervariable loops of endogenous immunoglobulin are processed through the endogenous degradative pathway and are presented to CD8+ T cells in the context of MHC class I molecules. The implication of these findings for processing and presentation of endogenous immunoglobulin peptides in B cells and network regulation by idiopeptides is discussed.
Contribution of α/β and γ/δ T lymphocytes to immunity against Mycobacterium bovis Bacillus Calmette Guérin: studies with T cell receptor‐deficient mutant mice
Authors: Ladel Christoph H. , Hess Jürgen , Daugelat Sabine , Mombaerts Peter , Tonegawa Susumu , Kaufmann Stefan H. E. 
Published: March 2007

AbstractMutant mice with defined T cell deficiencies were infected with Mycobacterium bovis bacillus Calmette Guérin (BCG) and the relative contribution of α/β T cells and γ/δ T cells to the host immune response was assessed. Recombinase activating gene (RAG‐1)−/− mutants as well as T cell receptor (TcR) β−/−, but not TcR‐δ−/−, mutants succumbed to M. bovis BCG infection and failed to develop granulomatous lesions. Antigen‐induced IFN‐γ production by spleen cells in vitro was abrogated in RAG‐1−/− mutants and markedly diminished in TcR‐β−/− and TcR‐δ−/− mice. Reconstitution experiments suggest that both α/β and γ/δ T cells are essential for antigen‐specific IFN‐γ secretion. Our data formally prove the crucial role of α/β T cells and reveal accessory functions of γ/δ T cells in optimum immunity against M. bovis BCG.
Generation of antigen‐specific CD4+ T cell lines from naive precursors
Authors: Mehta‐Damani Anita , Markowicz Sergiusz , Engleman Edgar G. 
Published: March 2007

AbstractThe conditions required for sensitizing naive T cells to nominal antigen are poorly understood. In this report we describe an in vitro system for generating antigen‐specific CD4+ T cells from previously unprimed individuals. Freshly isolated CD4+ T cells were cultured with keyhole limpet hemocyanin (KLH), sperm whale myoglobin (SWM), or human immunodeficiency virus (HIV) gp 160, antigens to which most persons have not been sensitized, in the presence of either dendritic cells (DC) or macrophages (MΦ). In short‐term (< 8 days) cultures, CD4+ T cells or their CD4+, CD45RA (naive) subpopulation mounted significant proliferative responses to KLH, SWM, and HIV gp160, but only if the antigens were presented by DC. In contrast, CD4+, CD45RO (memory) T cells responded poorly to these antigens, although they responded vigorously to tetanus toxoid, a recall antigen, presented by either DC or MΦ. KLH‐ and SWM‐specific CD4+ T cell lines were established from the starting population that had been sensitized in vitro, following repeated stimulation with antigen and MΦ in medium supplemented with interleukin‐2 and interleukin‐4. Despite the continued presence of these cytokines during T cell expansion, the expanded lines retained their ability to respond to the priming antigen in the absence of exogenous cytokines. When the CD45RA and CD45RO subpopulations were sensitized and expanded separately, the CD45RA cells alone gave rise to antigen‐specific T cell lines, while the CD45RO cells proliferated nonspecifically. These results demonstrate that human naive CD4+ T cells can be sensitized in vitro to nominal antigens presented by DC and that the sensitized cells can be expanded into long‐term lines that retain their antigen specificity.
Studies on the T cell dependence of natural IgM and IgG antibody repertoires in adult mice
Authors: Malanchère Evelyne , Marcos Miguel A. R. , Nobrega Alberto , Coutinho Antonio 
Published: March 2007

AbstractThe present experiments address the thymic dependence of IgM and IgG natural antibody repertoires in adult euthymic and athymic BALB/c mice, as well as in athymic animals reconstituted with a fixed number of syngeneic T cells. Within 3 weeks of the transfer of 107 syngeneic splenic T lymphocytes to athymic mice, the T cell compartment is essentially reconstituted in the peritoneal cavity (up to 80% of the numbers in euthymic animals), but is only 10–20% of controls in the spleen and lymph nodes. Early after transfer, there is an increase in the numbers of activated B cells and of immunoglobulin‐secreting cells in the spleen, and within 1–2 weeks, the serum concentrations of IgG1 and IgG2a are fully reconstituted to control levels (30–40‐fold increased). Multiparametric analyses of serum IgM and IgG repertoires revealed that euthymic and athymic mice share essentially all natural antibody reactivities towards syngeneic extracts of liver and muscle. When tested at the same immunoglobulin concentrations, however, nude sera consistently show higher values of reactivity in all detectable bands. The transfer of 107 splenic T cells into athymic mice results in a general decrease of serum IgM reactivities, some of which become undetectable, and in alterations of the serum IgG repertoire as early as 1 week, and for at least 4 weeks after transfer. T cell transfer, however, fails to restore the euthymic IgM and IgG repertoires within 4 weeks. The present observations demonstrate that, after limited T cell reconstitution of nude mice, there is a rapid and quantitatively important increase of serum IgG1 and IgG2a production; the serum IgM reactivity repertoire is qualitatively similar in euthymic and athymic animals, but is generally decreased by T cell activity; and the serum IgG repertoire, which is qualitatively similar in euthymic and athymic animals, is amplified by T cell activity and partially altered by T cell transfer into athymic animals. These results raise questions on the mechanisms of B cell activation and natural antibody repertoire selection in T cell‐deficient adult individuals.
Early parasite containment is decisive for resistance to Leishmania major infection
Authors: Laskay Tamás , Diefenbach Andreas , Röllinghoff Martin , Solbach Werner 
Published: March 2007

AbstractWe investigated the early spread of Leishmania major in various mouse strains. In BALB/c mice, which are extremely vulnerable to L. major infection, the parasites disseminated within 10‐24 h from the site of subcutaneous footpad infection in to the popliteal lymph node, spleen, lung, liver and bone marrow. Application of recombinant (r)IL‐12 prior to infection prevented the early dissemination of parasites into visceral organs and the animals healed the infection. In three mouse strains tested, C57BL/6, CBA/J and C3H/HeJ, which are all resistant to L. major infection, the parasites remained localized in the footpad and in the draining LN for 3 days without evidence of dissemination. In C57BL/6 mice, depletion of NK1.1+ cells or neutralization of interferon (IFN)‐γ prior to infection led to rapid parasite spreading with kinetics similar to those seen in susceptible animals. Depletion of either CD4+ or CD8+ T cells in vivo prior to infection did not alter the kinetics of dissemination in any mouse strain tested. Experiments with severe‐combined immunodeficient mice provided further evidence that parasite containment depends on natural killer cells and IFN‐γ, but is independent of T cells. The finding that all resistant mouse strains restrict the spread of the parasites within the first 24 h after infection strongly suggests that early parasite containment is closely associated with a resistant phenotype. The data show that local restriction of parasites in the pre‐T cell phase of the infection is mediated by the innate immune system and suggest that this function plays an important role in the development of a protective T cell response.
A B7‐1‐transfected human melanoma line stimulates proliferation and cytotoxicity of autologous and allogeneic lymphocytes
Authors: Sulé‐Suso Josep , Arienti Flavio , Melani Cecilia , Colombo Mario Paolo , Parmiani Giorgio 
Published: March 2007

AbstractB7 co‐stimulation is necessary to activate resting T cells upon antigen recognition by the T cell receptor. To see whether expression of B7 may render human melanoma cells able to stimulate T cells, a cloned melanoma line (Me1B6), which did not express B7‐1, was transfected with the human B7‐1 gene. In proliferation assays, B7‐1 transfected cells (Me1B6/B7) showed greater stimulatory activity of allogeneic and autologous peripheral blood lymphocytes (PBL) compared to parental, non‐transfected tumor cells. This effect was also seen when allogeneic CD8+ and CD4+ subpopulations were used as effectors. In these studies, activation of lymphocytes was B7‐1‐dependent and HLA classes I and II mediated. The higher proliferation correlated with an increased lytic activity by PBL stimulated with B7‐1+ tumor cells against the untransfected Me1B6. Furthermore, PBL from a metastatic melanoma patient stimulated by Me1B6/B7 developed an higher lytic activity not only against Me1B6 but also against their autologous, B7‐1− tumor. Finally, after Me1B6/B7 stimulation, PBL released interleukin (IL)‐2 and interferon‐γ, but not IL‐4, suggesting a Th1‐mediated response. These data support the use of B7‐1 transfected melanoma cells in the therapeutic vaccination of melanoma patients.
Internalization of B cell and pre‐B cell receptors is regulated by tyrosine kinase and phosphatase activities
Authors: Salamero Jean , Fougereau Michel , Seckinger Philippe 
Published: March 2007

AbstractPrior to the expression of the B cell antigen receptor, the μ heavy chain associates with two non‐polymorphic polypeptides, λ like and VpreB, which form a pseudo‐light chain complex in pre‐B cells and pre‐B cell lines. Surface expression of the so‐called pre‐B cell receptor (pre‐BCR) occurs only in the presence of Igα and Igβ, known to be involved both in B cell antigen receptor (BCR) signaling and trafficking. Although the pre‐BCR organization is consistent with an efficient transport to the cell surface, most of the newly synthesized receptor remains within the cells, and so far, no data are available concerning the rate of exit from the endoplasmic reticulum. Using the human pre‐B cell line Nalm‐6, we found that only a small fraction (2%) of newly synthesized pre‐BCR is transported to the cell surface within 4‐6 h after synthesis, where it is constitutively re‐internalized. Membrane Ig‐heavy chain cross‐linking induced internalization of surface pre‐BCR within a few minutes, and the mechanisms underlying endocytosis were analyzed by immunofluorescence and confocal microscopy. Prein‐cubation of the cells with either genistein or orthovanadate, which inhibit, respectively, tyrosine kinases and tyrosine phosphatases, blocked pre‐BCR internalization in a dose‐dependent manner, indicating that both activities are required for endocytosis. BCR internalization was also inhibited in a reversible manner by the drugs. In contrast, neither drug affected the size of the steadystate pool of internalized transferrin receptors. Thus, our data show that tyrosine phosphorylation and dephosphorylation are both required for cross‐linkinginduced pre‐BCR and BCR internalization.
Carrier‐reactive hapten‐specific cytotoxic T lymphocyte clones originate from a highly preselected T cell repertoire: implications for chemical‐induced self‐reactivity
Authors: Martin Stefan , Ruh Helga , Hebbelmann Sabine , Pflugfelder Ulrike , Rüde Barbara , Weltzien Hans Ulrich 
Published: March 2007

AbstractWe have recently described trinitrophenyl (TNP)‐specific cytotoxic T lymphocyte (CTL) clones from C57BL/6 mice specific for hapten‐modified peptides bearing a TNP‐lysine in a peripheral position, i.e. in position 7 of H‐2Kb‐bound octapeptides. CTL recognition of such determinants is always sequencedependent due to co‐recognition of TNP as well as amino acid side chains of the carrier peptide. By the use of glycine‐based designer peptides for primary induction of CTL in vitro, we have identified two sub‐epitopes on individual position 7‐haptenated peptides that form two TcR contact points and which can be independently recognized by cloned CTL. One of these sub‐epitopes is represented by the hapten itself, the other by the amino acids tyrosine and lysine in positions 3 and 4 of the carrier peptide, respectively. Immunization with such TNP‐modified peptides frequently results in the specific induction of CTL also reacting with the unmodified carrier peptides. DNA sequence analyses of the TcR revealed an extraordinary similarity of several independent TcR of CTL from individual mice and induced with different TNP‐peptides. These receptor similarities clearly correlate with structural elements common to the immunizing peptides and suggest their origin from positive thymic selection of TcR on Kb‐associated self‐peptides bearing Tyr in position 3. Our data provide additional information concerning the topology of TcR binding to peptide/MHC complexes with, but also without, TNP. They also indicate a mechanism which might explain the potential of chemicals or drugs to induce autoimmune phenomena.
Different forms of human vascular adhesion protein‐1 (VAP‐1) in blood vessels in vivo and in cultured endothelial cells: implications for lymphocyte‐endothelial cell adhesion models
Authors: Salmi Marko , Jalkanen Sirpa 
Published: March 2007

AbstractVascular endothelium plays a pivotal role in controlling leukocyte extravasation from the blood into the tissues. Vascular adhesion protein‐1 (VAP‐1) is a novel endothelial cell molecule which mediates lymphocyte binding to the vascular lining (Salmi, M., and Jalkanen, S., Science 1992. 257: 1407). In this study, we analyzed endothelial cell type‐specific differences of VAP‐1. In vivo, VAP‐1 is a 90/170‐kDa molecule which is mainly expressed on the lumenal surface and in cytoplasmic granules of peripheral lymph node‐type postcapillary venules (high endothelial venules, HEV). In tonsil HEV, VAP‐1 is modified with abundant sialic acids. VAP‐1 is also detectable in the cytoplasm of human umbilical vein endothelial cells (HUVEC) and in an endothelial cell hybrid EaHy‐926, although both cell types lack detectable surface VAP‐1. Cultured endothelial cells do not express MECA‐79‐defined peripheral lymph node addressins either. VAP‐1 was not translocated onto the endothelial cell surface after stimulation with multiple cytokines, mitogens or secretagogues which induced expression of other known endothelial adhesion molecules. Biochemical analyses revealed that VAP‐1 is a ∼ 180‐kDa protein in these endothelial cell types. Digestions with neuraminidase, O‐glycanase and N‐glycanase, as well as treatment of cells with tunicamycin and benzyl‐N‐acetylgalactosaminide, did not alter the molecular mass of VAP‐1 in EaHy‐926. Pulse‐chase experiments showed that VAP‐1 is directly synthesized as a 180‐kDa molecule without any detectable precursors. Thus, in cultured endothelial cells, VAP‐1 is a 180‐kDa protein which is devoid of post‐translational modifications, and in particular, lacks the sialic acids crucial for the function of VAP‐1 in tonsil vessels. Notably, the endothelial cell types commonly used as a model in studying lymphocyte‐endothelial cell interactions lack surface expression of VAP‐1 and peripheral node addressins, and hence are inherently of limited use in analyses of the initial adhesion of lymphocytes.
Glucocorticoids down‐regulate dendritic cell function in vitro and in vivo
Authors: Moser Muriel , De Smedt Thibaut , Sornasse Thierry , Tielemans Françoise , Chentoufi Aziz Alami , Muraille Eric , Van Mechelen Marcelle , Urbain Jacques , Leo Oberdan 
Published: March 2007

AbstractExogenous glucocorticoid hormones are widely used as therapeutical agents, whereas endogenous glucocorticoids may act as physiological immunosuppressants involved in the control of immune and inflammatory responses. The optimal activation of T lymphocytes requires two distinct signals: the major histocompatibility complex‐restricted presentation of the antigen and an additional co‐stimulatory signal provided by the antigen‐presenting cells. There is ample evidence that, among the cells able to present the antigen, the dendritic cells (DC) have the unique property to activate antigen‐specific, naive T cells in vitro and in vivo, and are therefore required for the induction of primary immune responses. In this work, we tested whether glucocorticoids affected the capacity of DC to sensitize naive T cells. Our data show that, in vitro, the steroid hormone analog dexamethasone (Dex) affects the viability of DC, selectively downregulates the expression of co‐stimulatory molecules on viable DC, and strongly reduces their immunostimulatory properties. In vivo, a single injection of Dex results in impaired antigen presenting function, a finding which correlates with reduced numbers of splenic DC. These results show that glucocorticoids regulate DC maturation and immune function in vitro and in vivo and suggest that this mechanism may play a role in preventing overstimulation of the immune system.
Induction of Th1 and Th2 CD4+ T cell responses by oral or parenteral immunization with ISCOMS
Authors: Maloy Kevin J. , Donachie Anne M. , Mowat Allan M. 
Published: March 2007

AbstractWe examined the ability of oral or parenteral immunization with immune stimulating complexes containing ovalbumin (ISCOMS‐OVA) to prime T cell proliferative and cytokine responses. A single subcutaneous immunization with ISCOMS‐OVA primed potent antigen‐specific proliferative responses in the draining popliteal lymph node, which were entirely dependent on the presence of CD4+ T cells. CD8+ T cells did not proliferate in vitro even in the presence of the appropriate peptide epitope and exogenous interleukin (IL)‐2. Primed popliteal lymph node cells produced IL‐2, IL‐5 and interferon (IFN)‐γ, but not IL‐4 when restimulated with OVA in vitro. Serum antigen‐specific IgG1 and IgG2a antibody responses were also primed by subcutaneous immunization with ISCOMS‐OVA, confirming the stimulation of both Th1 and Th2 cells in vivo. Spleen cells from subcutaneously primed mice produced a similar pattern of cytokines, indicating that disseminated priming had occurred. Oral immunization with ISCOMS‐OVA also primed local antigen‐specific proliferative responses in the mesenteric lymph node and primed an identical pattern of systemic cytokine responses in the spleen. The ability of ISCOMS to prime both Th1 and Th2 CD4+ T cell responses may be central to their potent adjuvant activities and confirm the potential of ISCOMS as future oral vaccine vectors.
Induction of diabetes in standard mice by immunization with the p277 peptide of a 60‐kDa heat shock protein
Authors: Elias Dana , Marcus Hadar , Reshef Tamara , Ablamunits Vitaly , Cohen Irun R. 
Published: March 2007

AbstractWe previously reported that immunity to the p277 peptide of the human 60‐kDa heat shock protein (hsp60) was a causal factor in the diabetes of non‐obese diabetic (NOD) mice, which are genetically prone to develop spontaneous autoimmune diabetes. The present study was done to test whether immunization with the p277 peptide could cause diabetes in standard strains of mice. We now report that a single administration of the p277 peptide conjugated to carrier molecules such as bovine serum albumin or ovalbumin can induce diabetes in C57BL/6 mice and in other strains not genetically prone to develop diabetes. The diabetes was marked by hyperglycemia, insulitis, insulin autoantibodies, glucose intolerance and low blood levels of insulin. The diabetes could be transferred to naive recipients by anti‐p277 T cell lines. Similar to other experimentally induced autoimmune diseases, the autoimmune diabetes remitted spontaneously. After recovery, the mice were found to have acquired resistance to a second induction of diabetes. Susceptibility to induced diabetes in C57BL/6 mice was influenced by sex (males were much more susceptible than were females) and by class II genes in the major histocompatibility complex (B6.H‐2bm12 mice with a mutation in the MHC‐II molecule were relatively resistant). Other strains of mice susceptible to induced diabetes were C57BL/KSJ, C3HeB/FeJ, and NON/Lt. BALB/c and C3H/HeJ strains were relatively resistant. Immunization to p277‐carrier conjugates could also induce transient hyperglycemia in young NOD mice, but upon recovery from the induced diabetes, the NOD mice were found to have acquired resistance to later development of spontaneous diabetes. Thus, T cell immunity to the p277 peptide can suffice to induce diabetes in standard mice, and a short bout of induced diabetes can affect the chronic process that would otherwise lead to spontaneous diabetes in diabetes‐prone NOD mice.