bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of T cells in SCID mice grafted with fetal thymus from AKR mice or F344 rats
Authors: Maeda Ken‐Ichi , Nagasawa Hideyuki , Furukawa Atsuko , Hisaeda Hajime , Maekawa Yoichi , Manabe Tetsuya , Kudo Eiji , Good Robert A. , Himeno Kunisuke 
Published: March 2007

AbstractTo examine the development of T cells within an allogeneic or xenogeneic environment, we engrafted the fetal thymus from AKR mice or F344 rats under the kidney capsule of SCID mice (mTG and rTG mice). T lymphopoiesis developed in SCID mice 2 months after transplantation, although the ratio of CD4/CD8 in both experimental groups was different from that of normal control. T cells in mTG mice did not show in vitro proliferation or cytotoxicity against either host‐type C.B‐17 (H‐2d) or donor‐type AKR (H‐2k) cells, while they exerted potent activities against third‐party BIO (H‐2b) cells. In contrast, T cells in rTG mice exhibited proliferation against both host‐type C.B‐17 and donor‐type F344 rat cells. Consistently, graft‐vs.‐host disease symptoms developed in these mice and histological examination showed impressive infiltration of lymphocytes into the skin or into the mucosal layers of the stomach. Activated state of T cells in rTG mice was also evidenced by the positive expression of interleukin‐2 receptor. Taken together, fetal thymus appears to contain progenitor cells which are sufficient for in vivo reconstitution of T lymphopoiesis, but species‐specific environment is important for the induction of tolerance. In mTG mice, Vβ6+ T cells reactive to donor Mlsa determinants and Vβ3+ T cells reactive to host Mlsc determinants were deleted, suggesting that tolerance was regulated mainly by clonal deletion. By contrast, Vβ11+ T cells reactive to Mlsf determinants were not deleted possibly due to the lack of their ligands.
The invariant chain induces compact forms of class II molecules localized in late endosomal compartments
Authors: Humbert Martine , Raposo Graça , Cosson Pierre , Reggio Hubert , Davoust Jean , Salamero Jean 
Published: March 2007

AbstractThe invariant chain (Ii) binds to newly synthesized major histocompatibility complex (MHC) class II molecules and is targeted to an acidic compartment where it is degraded. To evaluate its role on the conformation and the subcellular distribution of murine MHC class II molecules we have established stable L cell transfectants expressing class II IAk heterodimers alone or in conjunction with p31 and p41 Ii chains. In these cells, class II molecules were present under three forms: αβ heterodimers bearing high mannose carbohydrate moieties, and fully glycosylated αβ heterodimers that are sensitive or resistant to sodium dodecyl sulfate dissociation at 20 °C. The latter class II molecules called compact heterodimers, were here highly induced in Ii‐positive cells. Using in situ iodination of endosomal compartments, class II heterodimers were detected in late endosomal compartments essentially as compact forms in Ii‐positive cells, and as non‐compact forms in Ii‐negative cells. Using confocal microscopy, IAk molecules were located in compartments distinct from early endosomes labeled with transferrin, but partially coincident with vesicles containing fluid‐phase markers, and highly coincident with compartments containing large amounts of cathepsins B, D, H, and L in Ii‐positive and Ii‐negative cells. At the ultrastructural level, class II molecules were mostly present in multivesicular bodies, even without Ii expression. But Ii chains were needed to induce an efficient presentation of the hen egg lysozyme antigen and were sufficient to promote a major conformational change of the late endosomal, and/or lysosomal resident, class II molecules. Ii molecules are presumably playing a chaperoning function favoring the association of peptides with class II molecules in endosomal compartments.
Generation of a novel CD8+ cytotoxic T lymphocyte that requires soluble factor to lyse autologous antigen‐presenting cells
Authors: Yoshizumi Hideyuki , Kamikawaji Nobuhiro , Nishimura Yasuharu , Sasazuki Takehiko 
Published: March 2007

AbstractWe reported the existence of high and low responders to the streptococcal cell wall antigen (SCW) in the human population. To analyze the mechanism of the low responsiveness to SCW at the cellular level, we established SCW‐specific CD4+ T cell lines. During the course of generation of a SCW‐specific CD4+ T cell line restricted by HLA‐DQ from a low responder, we obtained autoreactive CD8+ cytotoxic T lymphocytes as a cell line (HYCD8). They proliferated in the presence of autologous monocytes and IL‐2, without SCW. HYCD8 lysed autologous monocytes and Epstein‐Barr virus‐transformed B lymphoblastoid cell line (BLCL). This cytotoxic activity was specifically inhibited by an anti‐HLA class I framework monoclonal antibody and restricted by HLA‐B52 or B54 specificity, as judged by killing activity against panel cells and HLA class I‐transfected BLCL. It was unique to HYCD8 that the HLA class I‐restricted cytotoxicity was observed only in the presence of soluble factor with low molecular mass (< 104 Da) produced mainly by B cells, which could not be replaced by known cytokines and their mixtures. We thus describe novel HLA class I‐restricted cytotoxic CD8+ T cells that kill antigen‐presenting cells in a soluble factor‐dependent manner.
Identification of new B cell epitopes in the sera of rheumatoid arthritis patients using a random nanopeptide phage library
Authors: Dybwad Anne , Førre Øystein , Kjeldsen‐Kragh Jens , Natvig Jacob B. , Sioud Mouldy 
Published: March 2007

AbstractA random nanopeptide phage library was used to screen a pool of immunoglobulin fractions obtained from rheumatoid arthritis (RA) patients. After three rounds of panning, random individual phages were selected by their capacity to react with individual sera from RA patients.By sequencing the inserts corresponding to the peptides displayed on the surface of the phages, we found that phages displaying particular peptides were overrepresented in the selected libraries. The peptides displayed by these phages were: pep1 = Ala‐Asp‐Gly‐Gly‐Ala‐Gln‐Gly‐Thr‐Ala; pep2 = Pro‐Gly‐Pro‐Ser‐Arg‐Ala‐His‐Phe‐Leu; pep3 = Leu‐Ser‐Ser‐Arg‐Glu‐Pro‐Gln‐Ala‐Arg; pep4 = Arg‐Leu‐Thr‐Arg‐Glu‐Leu‐Tyr‐Ala‐Gln and pep5 = Tyr‐Thr‐Gln‐Lys‐His‐Gln‐Ala.The percentage of sera positive for pep1 was higher in RA patients as compared to the normal adults (p 0.0004) and the reacting antibody was mainly of IgG isotype. The specificity of binding to the phage displaying pep1 was confirmed by competition experiments using both isolated phages and a synthetic peptide. Interestingly, a mutated phage displaying only Ala‐Asp‐Gln‐Gly‐Thr‐Ala had no significant reactivity with the sera, indicating that the amino acids (Gly‐Gly‐Ala) of pep1 are the vital for the binding. Taken together this study demonstrates that it is possible to select specific ligands from a random phage library using sera from RA patients. In addition, this approach could be useful for identifying peptide antigens that might be part of causitive agents in autoimmune diseases.
Carrier‐mediated uptake and presentation of a major histocompatibility complex class I‐restricted peptide
Authors: Brander Christian , Wyss‐Coray Tony , Mauri Davide , Bettens Florence , Pichler Werner J. 
Published: March 2007

AbstractAntigenic peptides derived from endogenous or viral proteins can associate with class I or class II major histocompatibility complex (MHC) molecules, while exogenous antigens are endocytosed, processed intracellularly and presented on MHC class II molecules. Here we describe a method that allows the presentation of an MHC class I‐restricted antigenic peptide on MHC class I molecules, although it was taken up from the outside. The HLA‐A2‐restricted influenza virus matrix protein‐derived peptide (flu, 57–68) was used either in soluble form or coupled via an S‐S bridge to transferrin (Tf‐flu). Target cells were incubated with flu or Tf‐flu and the effective antigen presentation was detected in a cytotoxicity assay using flu peptide‐specific, HLA‐A2‐restricted CD8+ cytotoxic T lymphocytes. Sensitization of target cells with Tf‐flu required 5 to 10 times higher molar concentrations of peptide compared to sensitization with soluble free peptide. The Tf‐flu construct was taken up by the cells via the Tf receptor (CD71) as the binding of Tf‐flu was blocked by an excess of Tf. In contrast to the flu peptide, cytotoxicity elicited by Tf‐flu was blocked by brefeldin A but not by chloroquine nor inhibitors of intracellular reducing steps, like 1‐buthionine‐(s, r)‐sulfoximine or n‐ethylmaleimide. Presentation of the flu peptide derived from Tf‐flu construct is not hindered in the mutant T2 cell line, which lacks genes coding for transporter proteins for antigenic peptides (TAP1/TAP2) and proteasomes subunits, suggesting that the processing pathway described in this report may involve TAP‐independent steps.
Major histocompatibility complex class I‐binding peptides are recycled to the cell surface after internalization
Authors: Abdel Motal Ussama M. , Zhou Xianzheng , Joki Annalena , Siddiqi Abdur Rehman , Srinivasa B. R. , Stenvall Kristina , Dahmén Jan , Jondal Mikael 
Published: March 2007

AbstractCytotoxic T lymphocytes (CTL) recognize target antigens as short, processed peptides bound to major histocompatibility complex class I (MHC‐I) heavy and light chains (β2‐microglobuhn; β2 m).The heavy chain, which comprise the actual peptide binding α‐1 and α‐2 domains, can exist at the cell surface in different forms, either free, bound to β2m or as a ternary complex with β2m and peptides. MHC‐I chains are also known to internalize, and recycle to the cell surface, and this has been suggested to be important in peptide presentation. Whether MHC‐I‐bound peptides also can recycle is not known. We have investigated this by using both peptide transporter mutant RMA‐S cells and EL4 cells loaded with Db‐binding peptides, by two different approaches. First, peptides were covalently linked with galabiose (Galα4Gal) at a position which did not interfere with Db binding or immunogenicity, and peptide recycling tested with Gal2‐specific monoclonal antibodies. By flow cytometry, a return of Gal2 epitopes to the cell surface was found, after cellular internalization and cell surface clearance by pronase treatment. This peptide recycling could be discriminated from free fluid‐phase uptake and was inhibited by methylamine, chloroquine and low temperature (18°C) but not by leupeptin. Second, specific CTL were reacted with peptide‐loaded target cells after complete removal of surface Db molecules by pronase, and after different times of incubation at 37C to allow reexpression. By this procedure, reappearance of target cell susceptibility was confirmed. The results are in agreement with a model for optimizing peptide presentation by recycling through an intracellular compartment similar to early endosomes in certain antigen‐presenting cells.
IgE‐binding molecules (Mac‐2/ϵBP) expressed by human eosinophils. Implication in IgE‐dependent eosinophil cytotoxicity
Authors: Truong Marie‐José , Gruart Valérie , Liu Fu‐Tong , Prin Lionel , Capron André , Capron Monique 
Published: March 2007

AbstractMacrophage cell‐surface protein 2 (Mac‐2), a galactose specific S‐type lectin identified in inflammatory macrophages, presents a high degree of homology with the rat IgE‐binding protein (ϵBP). In the present study, we show by different experimental approaches that human eosinophils can express Mac‐2/ϵBP. Flow cytometry analysis revealed that a large proportion of eosinophilic patients expressing binding sites for IgE on their eosinophil membrane, were able to bind anti‐Mac‐2 monoclonal antibody (mAb). Northern blot performed with eosinophil RNA hybridized with the human Mac‐2 or ϵBP cDNA probes revealed that eosinophils presented a unique transcript at 1.2 kb. Immunoprecipitation of eosinophil extracts with anti‐Mac‐2 mAb revealed the presence of a molecule of 29 kDa corresponding to Mac‐2 protein, as well as one additional molecule of 15 kDa, absent from control alveolar macrophages. The function of these molecules was investigated in a radiolabeled IgE binding assay. Anti‐Mac‐2 mAb as well as galactose and lactose saccharides significantly inhibited the binding of radiolabeled human myeloma IgE protein to eosinophils. Moreover, the dose‐dependent inhibition by anti‐Mac‐2 mAb of IgE‐dependent eosinophil‐mediated cytotoxicity towards parasite targets indicated the role of these IgE‐binding molecules in the function of human eosinophils. These results suggest that in addition to transmembrane receptors, lectin‐type molecules can participate in the IgE‐dependent effector function of eosinophils.
Enhancement of disease by neutralizing antiviral antibodies in the absence of primed antiviral cytotoxic T cells
Authors: Battegay Manuel , Kyburz Diego , Hengartner Hans , Zinkernagel Rolf M. 
Published: March 2007

AbstractThe effects of neutralizing antibodies on the disease course in mice infected with the noncytopathic lymphocytic choriomeningitis virus (LCMV) were evaluated. Whereas non‐neutralizing antisera exhibiting high enzyme ‐ linked immunosorbent assay titers had no effect on T cell responses and their consequences, neutralizing antisera modulated them variably. Neutralizing antibodies were able to prevent lethal choriomeningitis after intracerebral infection with a neurotropic LCMV‐isolate (ARMSTRONG) although they could not control local virus replication. The same antibodies exhibited little or no protective effect on choriomeningitis induced by LCMV‐WE, a viscerotrope isolate. Surprisingly, these antibodies rendered mice much more susceptible to choriomeningitis after intracerebral infection with LCMV DOCILE, a very rapidly spreading lymphocyto‐viscerotrope virus; in this situation antibodies prevented overwhelming infection which causes deletion of immunopathogenic cytotoxic T cell responses. Thus preexisting neutralizing antiviral antibodies had little influence on local virus spread in peripheral tissues but they reduced hematogenic spread and infection of antigen‐presenting cells; thereby they influenced the primary cytotoxic T cell (CTL) response and indirectly modulated the extent of T cell‐mediated immunopathology in peripheral organs. These results may explain why vaccines inducing neutralizing antibodies but no CTL may enhance an immunopathological disease caused by challenge infection with a noncytopathic virus.
Human IgM+IgD+ B cells, the major B cell subset in the peripheral blood, express Vϰ genes with no or little somatic mutation throughout life
Authors: Klein Ulf , Küppers Ralf , Rajewsky Klaus 
Published: March 2007

AbstractPeripheral blood B cells of a 67‐year‐old person were separated into IgM+IgD+, IgM+IgD−, and IgM−IgD− subsets, and nucleotide sequences of expressed immunoglobulin light chain variable (V) regions encoded by Vϰ3 and Vϰ4 gene family members were determined from amplified cDNA. V region sequences from IgM+IgD+ cells (the major B cell population in the blood) showed no or little somatic mutation (0.3%), in contrast to Vϰ sequences from IgM+IgD− and IgM−IgD− B cells (2.0% and 3.9%, respectively). This suggests that in the human like in the mouse, and independently of age, somatically mutated memory B cells accumulate in the compartment of IgM−IgD− cells, whereas the IgM+IgD+ subpopulation consists of cells whose antibody repertoire is mainly determined by V region gene rearrangements and N‐region insertion, at the molecular level. The somatically mutated IgM+IgD− cells may represent early descendants of IgM+IgD+ cells recruited into the memory cell compartment.
Activation of MAP kinases, pp90rsk and pp70‐S6 kinases in mouse mast cells by signaling through the c‐kit receptor tyrosine kinase or FcϵRI: rapamycin inhibits activation of pp70‐S6 kinase and proliferation in mouse mast cells
Authors: Tsai Mindy , Chen Rey‐Huei , Tam See‐Ying , Blenis John , Galli Stephen J. 
Published: March 2007

AbstractThe high‐affinity receptor for IgE, FcϵRI, represents the major cell surface structure through which mast cells express immunologically specific secretory function. By contrast, the stem cell factor receptor (SCFR), which is encoded by c‐kit, is essential for normal mast cell development. The signaling pathways initiated by the stimulation of mast cells through the FcϵRI, which lacks intrinsic kinase activity, and the SCFR, a member of the receptor tyrosine kinase family, generally have been regarded to be distinct. We report here that mouse mast cells stimulated either with SCF or with IgE and specific antigen exhibit a remarkably similar pattern of activation of mitogen‐activated protein kinases (MAPK), 90 kDa‐S6 kinases (pp90rsk), and pp70‐S6 kinases (pp70‐S6K). These results indicate that all three families of protein kinases are associated with the cell surface receptor‐dependent activation of secretion, as well as proliferation, in mast cells. We also show that the immunosuppressant rapamycin, but not FK506, can inhibit both SCF‐dependent pp70‐S6 kinase activation and SCF‐dependent proliferation in mouse mast cells, without suppressing IgE‐ and antigen‐dependent mediator release. These findings suggest that the activation of pp70‐S6 kinase represents an important link in the stimulation of cell proliferation by SCF. Our results also indicate that the intracellular signaling pathways initiated by stimulation of mast cells through the FcϵRI or the SCFR exhibit more overlap than has previously been appreciated.
Role of LFA‐1/ICAM‐1 in interleukin‐2‐stimulated lymphocyte proliferation
Authors: Vyth‐Dreese Florry A. , Dellemijn Trees A. M. , Frijhoff Anita , van Kooyk Yvette , Figdor Carl G. 
Published: March 2007

AbstractMajor adhesion routes between lymphoid cells involve the receptor/ligand pairs LFA‐l/ICAM‐1 and CD2/LFA‐3, in addition to VLA or CD44 molecules. In this study we evaluated the role of these adhesion receptors in the proliferative response of lymphoid cells to interleukin‐2 (IL‐2). Blocking studies were performed with a panel of monoclonal antibodies (mAb) directed against these adhesion molecules. Selective inhibition of recombinant (r)IL‐2‐induced cell proliferation was observed with mAb directed against the a or /3 subunit of LFA‐1 or to its ligand ICAM‐1. Interestingly, rIL‐2‐induced proliferation was also inhibited by NKI‐L16, an anti‐la antibody known to enhance cell‐cell interaction. Resting lymphocytes were preferentially susceptible to the inhibition, particularly in an early phase of culture and when stimulated with a relatively low dose of rIL‐2. By using mAb that specifically could block distinct rIL‐2 activation pathways, LFA‐l/ICAM‐1 interaction was found to be required for p55 IL‐2 receptor (IL‐2R)‐mediated interaction of rIL‐2 with its high‐affinity receptor, but not for p75 IL‐2R‐mediated responses. Furthermore, it was shown that the rIL‐2 response of T lymphocytes, but not of natural killer cells, was dependent on LFA‐l/ICAM‐1 interaction. This suggests that LFA‐l/ICAM‐1 interaction is required for an optimal rIL‐2 response of cells capable of IL‐2 secretion. Our data provide evidence for the hypothesis that adhesion receptor‐directed release of IL‐2 may result in a locally high concentration of IL‐2 that triggers high‐affinity IL‐2R signaling and up‐regulates p55 IL‐2R to enhance cytokine responsiveness.
Antigen‐presenting human T cells and antigen‐presenting B cells induce a similar cytokine profile in specific T cell clones
Authors: Wyss‐Coray Tony , Gallati Harold , Pracht Inge , Limat André , Mauri David , Frutig Karin , Pichler Werner J. 
Published: March 2007

AbstractOne of the factors that may influence the cytokine secretion profile of a T cell is the antigen‐presenting cell (APC). Since activated human T cells have been described to express major histocompatibility complex (MHC) class II molecules as well as costimulatory molecules for T cell activation, like e.g. ICAM‐1, LFA‐3 and B7, they might play a role as APC and be involved in the regulation of T‐T cell interactions. To define further the role of T cells as APC we tested their capacity to induce proliferation and cytokine production in peptide‐ or allospecific T cell clones and compared it with conventional APC, like B lymphoblasts (B‐LCL) or HTLV‐1 ‐ transformed T cells, or with non‐classical APC, like activated keratinocytes or eosinophils. CD4+, DP‐restricted T cell clones specific for a tetanus toxin peptide (amino acids 947‐967) and CD4+, DR‐restricted allospecific Tcell clones produced interleukin (IL)‐2, IL‐4, tumor necrosis factor‐α and interferon‐γ (IFN‐γ) after phorbol 12‐myristate 13‐acetate and ionomycin stimulation and a more restricted cytokine pattern after antigen stimulation. Dose‐response curves revealed that the antigen‐presenting capacity of activated, MHC class II+, B7+ T cells was comparable to the one of B‐LCL. Both APC induced the same cytokine profile in the T cell clones despite a weaker proliferative response with T cells as APC. Suboptimal stimulations resulted in a lower IFN‐γ/IL‐4 ratio. Cytokine‐treated, MHC class II+ keratinocytes and eosinophils differed in the expression of adhesion molecules and their capacity to restimulate T cell clones. The strongly ICAM‐1‐positive keratinocytes induced rather high cytokine levels. In contrast, eosinophils, which express only low densities of MHC class II and no or only low levels of adhesion molecules (B7, ICAM‐1 and LFA3), provided a reduced signal resulting in a diminished IFN‐γ/IL‐4 ratio. We conclude that non‐classical APC differ in their capacity to restimulate T cell clones, whereby the intensity of MHC class II and adhesion molecules (B7, ICAM‐1) expressed seems to determine the efficacy of this presentation.
The lymphocyte surface antigen CD38 acts as a nicotinamide adenine dinucleotide glycohydrolase in human T lymphocytes
Authors: Gelman Laurent , Deterre Philippe , Gouy Hélène , Boumsell Laurence , Debré Patrice , Bismuth Georges 
Published: March 2007

AbstractThe extracellular domain of the lymphocyte surface antigen CD38 has been recently shown to share a high sequence homology with a nicotinamide adenine dinucleotide (NAD+)‐specific hydrolyzing enzyme cloned from the ovotestis of the gastropod Aplysia (E. States, D. J., Walseth, T. F., Lee, H. C, Trends Biochem. Sci. 1992. 17: 495). In agreement with this finding, we present here evidence that CD38‐overexpressingT cells, such as human thymocytes and cells from the human HPB‐ALL T cell line, exhibit a NAD+‐hydrolyzing enzymatic activity present on the outer surface of the cell membrane. In contrast, T lymphocytes with relatively low levels of CD38 marker, such as the human Jurkat cell line, display a lower activity. This suggests a relationship between ecto‐NAD+ glycohydrolase activity and CD38 expression, as confirmed here when comparing wild‐type Jurkat cells and a Jurkat cell variant overexpressing the CD38 molecule. Moreover, CD38 immunoprecipitates from thymocytes behave as an authentic NAD+ glycohydrolase enzyme: it transforms NAD+ stoichiometrically into nicotinamide plus adenosine 5′‐diphosphoribose. Altogether these results strongly support the assumption that CD38 is actually a lymphocyte‐specific NAD+‐hydrolyzing enzyme, a finding that give new prospects to understand the in vivo function of this cell membrane protein.