bluuebunny/crossref_metadata_2025_split huggingface dataset:
A recombinant single‐chain human class II MHC molecule (HLA‐DR1) as a covalently linked heterotrimer of α chain, β chain, and antigenic peptide, with immunogenicity in vitro and reduced affinity for bacterial superantigens
Authors: Zhu Xiaojie , Bavari Sina , Ulrich Robert , Sadegh‐Nasseri Scheherazade , Ferrone Soldano , McHugh Louise , Mage Michael 
Published: March 2007

AbstractMajor histocompatibility complex (MHC) class II molecules bind to numerous peptides and display these on the cell surface for T cell recognition. In a given immune response, receptors on T cells recognize antigenic peptides that are a minor population of MHC class II‐bound peptides. To control which peptides are presented to T cells, it may be desirable to use recombinant MHC molecules with covalently bound antigenic peptides. To study T cell responses to such homogenous peptide‐MHC complexes, we engineered an HLA‐DR1 cDNA coding for influenza hemagglutinin, influenza matrix, or HIV p24 gag peptides covalently attached via a peptide spacer to the N terminus of the DR1 β chain. Co‐transfection with DR α cDNA into mouse L cells resulted in surface expression of HLA‐DR1 molecules that reacted with monoclonal antibodies (mAb) specific for correctly folded HLA‐DR epitopes. This suggested that the spacer and peptide did not alter expression or folding of the molecule. We then engineered an additional peptide spacer between the C terminus of a truncated β chain (without transmembrane or cytoplasmic domains) and the N terminus of full‐length DR α chain. Transfection of this cDNA into mouse L cells resulted in surface expression of the entire covalently linked heterotrimer of peptide, β chain, and α chain with the expected molecular mass of approximately 66 kDa. These single‐chain HLA‐DR1 molecules reacted with mAb specific for correctly folded HLA‐DR epitopes, and identified one mAb with [MHC + peptide] specificity. Affinity‐purified soluble secreted single‐chain molecules with truncated α chain moved in electrophoresis as compact class II MHC dimers. Cell surface two‐chain or single‐chain HLA‐DR1 molecules with a covalent HA peptide stimulated HLA‐DR1‐restricted HA‐specific T cells. They were immunogenic in vitro for peripheral blood mononuclear cells. The two‐chain and single‐chain HLA‐DR1 molecules with covalent HA peptide had reduced binding for the bacterial superantigens staphylococcal enterotoxin A and B and almost no binding for toxic shock syndrome toxin‐1. The unique properties of these engineered HLA‐DR1 molecules may facilitate our understanding of the complex nature of antigen recognition and aid in the development of novel vaccines with reduced superantigen binding.
Interleukin‐12 acts as an adjuvant for humoral immunity through interferon‐γ‐dependent and ‐independent mechanisms
Authors: Metzger Dennis W. , McNutt Renee M. , Collins John T. , Buchanan J. Matthew , Van Cleave Victor H. , Dunnick Wesley A. 
Published: March 2007

AbstractInterleukin‐12 (IL‐12) is a pivotal cytokine that has dramatic effects on cellmediated immunity. It is now becoming increasingly recognized that IL‐12 also strongly controls humoral immunity. We have investigated the mechanism by which IL‐12 induces alterations in antibody isotype expression by determining the influence of IL‐12 on in vitro immunoglobulin (Ig) production in polyclonally activated murine spleen cell cultures. Cells exposed to IL‐12 plus lipopolysaccharide or anti‐CD40 monoclonal antibody showed dramatically elevated IgG2a and suppressed IgG1 production compared to cells cultured in the absence of IL‐12. IL‐12 treatment of spleen cell cultures induced expression of γ2a germ‐line transcripts, consistent with initiation of switch recombination to IgG2a. In addition, exposure of limiting dilution cultures to IL‐12 increased IgG2a+ cell precursor frequency. All of the above results were dependent on interferon‐γ (IFN‐γ). However, in the absence of IFN‐γ, IL‐12 still had significant effects on Ig secretion. Specifically, IL‐12 enhanced IgG1 and IgG2b anti‐DNP antibody levels in mice containing specific disruptions in the IFN‐γ gene. Our results suggest that IL‐12 induces T helper type 1 and natural killer cells to secrete large amounts of IFN‐γ which then causes B cells to switch to IgG2a and IgG3 production. In addition, IL‐12 has direct or indirect effects on B cells that are independent of IFN‐γ. The IFN‐γ‐independent effects may include enhancement of Ig expression by post‐switched cells.
The effects of CD3, CD4 and CD28 signaling on lymphocytes during human immunodeficiency virus‐1 infection
Authors: Guntermann Christine , Zheng Richard , Nye Keith E. 
Published: March 2007

AbstractWe investigated the effects of early human immunodeficiency virus‐1 infection (HIV‐1) on CD4‐ and CD28‐mediated co‐signaling of the T cell receptor (TCR)/CD3 complex in peripheral blood lymphocytes (PBL). CD4 ligation either alone or in conjunction with TCR occupancy resulted in abrogated signaling shown by impaired co‐association of the tyrosine kinase ZAP‐70 with the CD3‐ζ chains in virally infected PBL. In addition, down‐regulation of CD4‐associated TCR signaling resulted in diminished tyrosine phosphorylation of mitogen‐activated protein kinase (MAPK), a serine threonine kinase which is critically involved in the regulation of transcription factors. Furthermore, these aberrant CD4‐driven signals rendered HIV‐1‐infected PBL susceptible to activation‐induced cell death. By contrast, cross‐linking of the TCR/CD3 complex with the CD28 receptor improved tyrosine phosphorylation of MAPK and salvaged infected PBL from activation‐induced cell death. Our data demonstrate the importance of appropriate CD3, CD4 and CD28 co‐stimulatory function to prevent apoptosis. The CD4‐mediated signaling defects of the TCR could contribute to the loss of immunocompetent cells during HIV‐1 infection via activation‐induced cell death, whereas stimulation through the CD28 pathway could reverse these detrimental effects.
Correction of Fas (CD95) deficiency by haploidentical bone marrow transplantation
Authors: Benkerrou Malika , Le Deist Françoise , de Villartay Jean Pierre , Caillat‐Zucman Sophie , Rieux‐Laucat Frédéric , Jabado Nada , Cavazzana‐Calvo Marina , Fischer Alain 
Published: March 2007

AbstractRecently, an inherited syndrome characterized by nonmalignant lymphoprolif‐eration with autoimmune manifestations, caused by mutations of the Fas (CD95) receptor gene has been described. Because of disease severity, i.e. unremitting lymphoproliferation in a child with complete Fas deficiency, a haploidentical bone marrow transplantation (BMT) was performed despite the known resistance of Fas‐deficient lpr mice to bone marrow transplantation. Marrow graft was rejected early; however, a second attempt using bone marrow from the mother led to engraftment and to control of lymphoproliferation and of autoimmune thrombocytopenia up to the last follow‐up at 24 months after BMT. This single case shows that resistance to bone marrow engraftment caused by survival of Fas‐deficient cells can be overcome.
Ligation of the T cell antigen receptor induces tyrosine phosphorylation of p105CasL, a member of the p130Cas‐related docking protein family, and its subsequent binding to the Src homology 2 domain of c‐Crk
Authors: Kanda Hiroko , Mimura Toshihide , Morino Noritsugu , Hamasaki Ken , Nakamoto Tetsuya , Hirai Hisamaru , Morimoto Chikao , Yazaki Yoshio , Nojima Yoshihisa 
Published: March 2007

Abstractp105CasL (CasL) is a recently identified signaling molecule closely related to the p130Cas (Crk‐associated substrate) docking protein. CasL has a single Src homology (SH) 3 domain in its N‐terminal portion followed by multiple consensus motifs for binding to SH2 domains. Like original p130Cas, CasL undergoes tyrosine phosphorylation upon integrin‐mediated cell adhesion. In the present report, we provide direct evidence that CasL is also involved in T cell antigen receptor (TcR)‐mediated signal transduction. In binding studies in vitro using glutathione‐S‐transferase fusion proteins, we have identified 105‐ and 120‐kDa phosphotyrosyl proteins (pp105 and pp120, respectively) tightly bound to the SH2 domain of the Crk adapter protein in the H9 human T cell line after stimulation through the CD3/TcR complex. pp120, but not pp105, also bound to the SH3 of another adapter protein, Ash/Grb2. Immunoblotting with specific antibodies revealed that pp120 and pp105 were identical to the c‐cbl proto‐oncogene product (p120cbl) and CasL, respectively. Association between Crk and tyrosine‐phosphorylated CasL after TcR stimulation was also confirmed in vivo. CasL phosphorylation induced by TcR ligation reached maximal levels within 2 min and rapidly declined thereafter, whereas the integrin‐dependent response occurred slowly and was more prolonged. Finally, we demonstrated that Crk/CasL association occurred in peripheral blood T lymphocytes in response to TcR engagement. Our findings suggest that CasL is involved in T cell activation signals and resides at a point where two distinct receptor‐mediated signaling pathways converge. This provides one mechanism by which integrins may mediate T cell co‐stimulation.
An interleukin‐7 internet for intestinal intraepithelial T cell development: Knockout of ligand or receptor reveal differences in the immunodeficient state
Authors: Fujihashi Kohtaro , McGhee Jerry R. , Yamamoto Masafumi , Peschon Jacques J. , Kiyono Hiroshi 
Published: March 2007

AbstractBoth interleukin‐7 (IL‐7) and IL‐7 receptor (R) gene knockout (IL‐7−/− and IL‐7R−/−) mice were employed in order to directly investigate the importance of the IL‐7 and IL‐7R signaling pathway for the development of intestinal intraepithelial lymphocytes (IEL). Loss of the IL‐7R‐specific gene resulted in complete deficiency of the γδ T cell lineage with lack of Vγ4‐ and Vγ7‐specific messages in the epithelium of the gastrointestinal (GI) tract in comparison to control mice of the same genetic background (∼ 40%). Disruption of the IL‐7‐specific gene resulted in marked, but not complete depletion of γδ T cells (2–3%) in IEL. Furthermore, mRNA for both Vγ4 and Vγ7 genes were detected in the γδ IEL subset of IL‐7−/− mice. The subtle differences between IL‐7−/− and IL‐7R−/− mice suggest that although IL‐7 controls most of the expansion and/or development of γδ IEL, another ligand binding to the IL‐7R also plays a discernable role. Furthermore, αβ IEL developed more slowly in IL‐7R−/− mice when compared with ligand knockouts; however, the frequency of IEL T cells subsequently increased with age and normal levels of CD3+ T cells expressing the αβ TCR were detected by 2 and 3 months of age in IL‐7−/− and IL‐7R−/− mice, respectively. The direct comparison of IL‐7 and IL‐7R−/− mice clearly supports the hypothesis that both IL‐7 and another IL‐7R binding molecule can influence the development of γδ T cells in the intestinal epithelium.
Elevated mutant frequencies in gene lacI in splenic lipopolysaccharide blasts after exposure to activated phagocytes in vitro
Authors: Felix Klaus , Lin Sophia , Janz Siegfried 
Published: March 2007

AbstractThe interaction of B lymphocytes with phagocytes is critical for shaping the humoral immune response, as well as various aspects of normal and malignant B cell development, and has therefore been studied by immunologists in great detail. However, one potential outcome of this confrontation is often neglected, namely the mutagenicity of phagocytes to B lymphocytes. We are interested in phagocyte‐induced B cell mutagenesis and have conducted a feasibility study on the utility of a transgenic reporter assay to evaluate mutant frequencies in B cells that have encountered phagocytes. An in vitro co‐incubation system was designed in which splenic lipopolysaccharide (LPS) blasts carrying a phage Δ‐derived lacI transgene were exposed to pristane‐elicited peritoneal exudate cells (PEC). Mutant frequencies in LPS blasts were significantly increased (up to 6‐fold) when the cells were co‐incubated with PEC that had been stimulated by phorbol myristate acetate to undergo an oxidative burst. The lacI‐based transgenic mutation assay proved also useful for assessing mutagenicity in vivo, as demonstrated by the detection of elevated mutant frequencies in the spleen (3‐fold) and the inflammatory granuloma (4.7‐fold) obtained from pristane‐treated mice. We propose to utilize the lacI‐based transgenic mutagenesis assay as a tool to evaluate mutational levels during normal and aberrant B cell differentiation.
Expression and functions of the high‐affinity IgE receptor on human platelets and megakaryocyte precursors
Authors: Joseph Michel , Gounni Abdelillah Soussi , Kusnierz Jean‐Pierre , Vorng Han , Sarfati Marika , Kinet Jean‐Pierre , Tonnel André‐Bernard , Capron André , Capron Monique 
Published: March 2007

AbstractPlatelets can be activated by IgE and are therefore involved in IgE‐mediated effector mechanisms against parasites and in allergic disorders. Here we show that, besides the low‐affinity IgE receptor (FcεRII/CD23), platelets express the high‐affinity receptor for IgE (FcεRI). Flow cytometry analysis revealed the existence of surface FcεRI on platelets with a large heterogeneity among individual donors, and a low proportion of platelets co‐expressing FcεRI and FcεRII/CD23. Northern hybridization and reverse transcription polymerase chain reaction confirmed the presence of mRNA encoding the α, β and γ chains of FcεRI in platelets and in their megakaryocytic precursors. Cross‐linking of FcεRI with monoclonal antibody (mAb) to α chain using either the whole molecule or F(ab′)2 triggered platelet cytotoxicity for Schistosoma mansoni larvae. Anti‐FcεRII/CD23 mAb significantly inhibited IgE‐ or FcεRI‐mediated cytotoxicity, indicating down‐regulatory effects of FcεRII/CD23 on FcεRI‐dependent functions. These results demonstrate functional properties for FcεRI on platelets and indicate unsuspected interactions between the low‐ and the high‐affinity IgE receptors.
Size‐dependent effect of IgA on the IgA Fc receptor (CD89)
Authors: Reterink Thomas J. F. , van Zandbergen Ger , van Egmond Marjolein , Klar‐Mohamad Ngaisah , Morton Craig H. , van de Winkel Jan G. J. , Daha Mohamed R. 
Published: March 2007

AbstractThe IgA Fc receptor (FcR; CD89) is expressed on several types of cells of the myeloid cell lineage. We investigated whether different sizes of heat‐aggregated IgA (aIgA) bind to CD89 and subsequently induce cellular activation. As a model we used the murine B cell line IIA1.6 transfected with CD89 or IIA1.6 cells transfected with CD89 as well as with the FcR γ chain to study the binding of IgA to CD89. When these cells expressing CD89 were incubated with monomeric IgA, no significant binding of IgA to the cells was detectable by fluorescence‐activated cell sorter analysis; however, incubation of the cells with aggregated IgA resulted in 93 ± 2% positive cells. Incubation of the cells with different sizes of IgA‐containing aggregates revealed optimal binding with aggregates containing five to six molecules of IgA per aggregate. No difference was observed between the binding to CD89 of both IgA1‐ or IgA2‐containing aggregates. Furthermore, the binding of aIgA was found to be CD89‐specific, since the binding of IgA was completely inhibited by the CD89‐specific monoclonal antibody My43 and no detectable binding occurred to the IIA1.6 parent cell line. Activation studies using interleukin‐2 (IL‐2) production as a marker, showed that the FcR γ chain is necessary to induce cellular activation. Only cells transfected with both CD89 and the FcR γ chain (CD89+/γ+) enhance the IL‐2 production 10–12‐fold upon stimulation with aggregates of IgA. Furthermore, triggering of CD89 only results in increase of intracellular calcium concentration ([Ca2+]i) in cells co‐expressing FcR γ chain. Mutation of the tyrosine residues in the FcR γ chain immunoreceptor tyrosine‐based activation motif of the FcR γ chain abolishes this increase in [Ca2+]i, indicating association and involvement of the FcR γ chain in CD89‐mediated signaling.
CD2‐mediated signaling in T cells lacking the ζ‐chain‐specific immune receptor tyrosine‐based activation (ITAM) motif
Authors: Steeg Christiane , Von Benin Arne , Mittrücker Hans‐Willi , Malissen Bernard , Fleischer Bernhard 
Published: March 2007

AbstractT lymphocytes can be activated via the T cell receptor (TCR) or by triggering through a number of other surface structures, including the CD2 co‐receptor molecule. Signaling through the CD2 molecule was shown previously to be dependent on the TCR‐associated ζ‐chain. Here, we show that CD2‐induced activation also functions in T cells which express ζ‐chains lacking a functional immune‐receptor tyrosine‐based activation motif (ITAM). TCR‐positive T cells that express only the transmembrane part of the ζ‐chain protein and thus lack a functional ζ‐derived ITAM readily produce interleukin (IL)‐2 when cross‐linked with CD2‐specific monoclonal antibodies (mAb). TCR‐negative T cell hybridomas expressing minimal receptors consisting of an extracellular CD25 and an intracellular ζ‐chain‐derived segment were effectively stimulated via CD2‐specific mAb. For CD2‐mediated co‐stimulation of TCR‐negative cells, two ζ‐chain‐derived ITAM were sufficient to induce IL‐2 when the CD2 molecules were co‐cross‐linked with the chimeric CD25‐ζ molecules. Taken together, our results show that CD2‐induced signaling does not necessarily employ the ζ‐chain in TCR‐positive cells and that CD2‐dependent co‐stimulation in TCR‐negative cells can be mediated via two functional ζ‐chain‐derived ITAM.
Mycobacterium bovis Bacillus Calmette Guérin infection prevents apoptosis of resting human monocytes
Authors: Kremer Laurent , Estaquier Jérôme , Brandt Eric , Ameisen Jean‐Claude , Locht Camille 
Published: March 2007

AbstractApoptosis plays an essential role in the development and homeostasis of multi‐cellular organisms. Some infectious agents interfere with this programmed cell death to their own benefit. Here, we show that infection of resting human monocytes with Mycobacterium bovis Bacillus Calmette Guérin (BCG) increases monocyte viability by preventing them from undergoing apoptosis. Heat‐killed BCG also prevented apoptosis, indicating that replication of BCG is not required to prevent cell death. Analysis of BCG‐infected monocytes revealed an up‐regulation of the A1 mRNA, whereas the bcl‐2 mRNA was not up‐regulated. Interestingly, preinfection with BCG renders the cells resistant to interleukin (IL)‐10‐induced apoptosis which may be one of the mechanisms mycobacteria use to modulate immune responses. BCG infection was also accompanied by an impairment of the capacity of monocytes to secrete IL‐10 and by an induction of the capacity to secrete tumor necrosis factor‐α, two cytokines known to induce and prevent human monocyte apoptosis, respectively. Since it has been reported that apoptosis is involved in killing of intracellular mycobacteria, the prevention of apoptosis may represent a strategy for mycobacterial survival in the infected host.
Overexpression of the death‐promoting gene bax‐α sensitizes human BL‐41 Burkitt lymphoma cells for surface IgM‐mediated apoptosis
Authors: Weinmann Pamela , Bommert Kurt , Mapara Markus Y. , Dörken Bernd , Bargou Ralf C. 
Published: March 2007

AbstractMajor regulators of programmed cell death, or apoptosis, are the members of the bcl‐2 gene family. Recently, we reported that surface(s) IgM triggering of the human B lymphoma cell line BL‐41 led to strong induction of bax‐α, a death‐promoting member of the bcl‐2 family, and subsequently to induction of apoptosis, suggesting a potential regulatory role of bax‐α in sIgM‐mediated cell death. In contrast, apoptosis‐resistant subclones of this cell line showed only weak bax‐α expression, which was not inducible by sIgM cross‐linking. In this study, we were able to demonstrate the functional significance of this observation. We stably transfected bax‐α into a BL‐41 subline resistant against sIgM‐mediated apoptosis. Several bax‐α overexpressing clones could be selected, which all showed enhanced sensitivity for sIgM‐mediated apoptosis. In contrast, no sensitive clone could be identified in a large number of mock controls. This clearly indicates that induction of bax‐α is a critical regulatory step, which sensitizes B cells for sIgM‐mediated apoptosis.
Chemotactic activity on mononuclear cells in the cerebrospinal fluid of patients with viral meningitis is mediated by interferon‐γ inducible protein‐10 and monocyte chemotactic protein‐1
Authors: Lahrtz Fritz , Piali Luca , Nadal David , Pfister Hans‐Walter , Spanaus Katharina‐Susanne , Baggiolini Marco , Fontana Adriano 
Published: March 2007

AbstractIn viral meningitis the inflammatory response involves activated T cells and monocytes which are recruited into the subarachnoid space. To identify the chemotactic signals attracting the cells to the site of infection in the meninges, we measured the levels of two CXC chemokines, interferon‐γ (IFN‐γ) inducible protein (IP)‐10 and monokine induced by IFN‐γ, four CC chemokines, monocyte chemotactic protein (MCP)‐1, RANTES, macrophage inflammatory protein (MIP)‐1α and MIP‐1β, as well as the cytokines interleukin (IL)‐15 and IL‐16 in the cerebrospinal fluid (CSF) of patients suffering from viral meningitis. The results point to an involvement of two chemokines, MCP‐1 and IP‐10, since (1) unlike the other cytokines, MCP‐1 and IP‐10 were present in 97 % and 79 % of the CSF, respectively, at concentrations sufficient to induce chemotaxis of mononuclear cells; (2) more than 90 % of the CSF of viral meningitis induced chemotaxis of peripheral blood mononuclear cells (PBMC) and all of them induced chemotaxis of activated T cells, and (3) the CSF‐mediated chemotaxis of PBMC was inhibited by anti‐MCP‐1 antibodies and chemotaxis of activated T cells was abolished by the combination of anti‐MCP‐1 and anti‐IP‐10 antibodies. Our data provide evidence that MCP‐1 and IP‐10 lead to accumulation of activated T cells and monocytes in the CSF compartment in viral meningitis.
Normal macrophage functions, but impaired induction of γδ T cells, at the site of bacterial infection in CD45 exon 6‐deficient mice
Authors: Fujise Shigeru , Kishihara Kenji , Lee Kyung‐Yil , Matsuzaki Goro , Nomoto Kikuo 
Published: March 2007

AbstractWe investigated the protective functions of macrophages and γδ T cells in adult CD45 exon 6‐deficient (CD45−/−) mice against an intraperitoneal (i.p.) infection with Listeria monocytogenes. γδ T cells are preferentially localized in the spleen, liver, and intraperitoneal cavity of the adult CD45−/− mice. Increased numbers of γδ T cells were observed after i.p. infection with L. monocytogenes in the peritoneal cavity of C57BL/6 (CD45+/+) mice but not in CD45−/− mice. The γδ T cells showed predominant usage of Vδ5 and Vδ6 rearranged to Jδ1 in the infected CD45−/− mice which are the same as those used by resident γδ T cells of noninfected CD45+/+ and CD45−/− mice. Furthermore, we analyzed the protective abilities of the CD45−/−, CD45+/+, and γδ T cell‐depleted mice at the early stage of the listerial infection. The numbers of bacteria in the spleens and livers of the CD45−/− mice 5 days after the listerial infection were almost ten times larger than those in the CD45−/− and γδ T cell‐depleted CD45+/+ mice. Macrophages showed normal antigen presentation, nitric oxide production and bactericidal activity for L. monocytogenes despite their lacking CD45 surface expression, suggesting that CD45‐negative macrophages have a minimal influence on the increased bacterial multiplication in the CD45−/− mice. These results suggest that the γδ T cells are induced by the bacterial infection in a CD45‐dependent manner, and that unresponsiveness of the γδ T cells results in only weak protection against L. monocytogenes in CD45−/− mice.