bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abnormalities of B cells and dendritic cells in SAMP1 mice
Authors: Haruna Hiroki , Inaba Muneo , Inaba Kayo , Taketani Shigeru , Sugiura Kikuya , Fukuba Yoh , Doi Hiroshi , Toki Junko , Tokunaga Rikio , Ikehara Susumu 
Published: March 2007

AbstractThe age‐related changes in the function of antigen‐presenting cells (APC) were examined using a substrain of senescence‐accelerated mouse (SAMP1). In the primary mixed lymphocyte reaction (MLR), dendritic cells (DC) from aged SAMP1 mice showed less stimulatory activity than those of age‐matched BALB/c or young SAMP1 mice. In the secondary MLR, the stimulatory activity of B cells was found to be lower in aged SAMP1 mice but not in age‐matched BALB/c or young SAMP1 mice. In addition, these age‐related decreases in the stimulatory activity of APC were found to be related to changes in the surface density of major histocompatibility complex class II and intercellular adhesion molecule‐1 (ICAM‐1) (but not B7‐1 or B7‐2 molecule) on APC (DC and B cells).
Abnormal CD45RC expression and elevated CD45 protein tyrosine phosphatase activity in LEC rat peripheral CD4+ T cells
Authors: Sakai Tohru , Agui Takashi , Matsumoto Kozo 
Published: March 2007

AbstractLEG rats are known to show a maturational arrest in the development of CD4+8+ to CD4+8− cells in the thymus. Despite the blockade of maturation of CD4+8− thymocytes, CD4+ T cells were observed in peripheral lymphoid organs, and these cells exhibit a defect in interleukin‐2 (IL‐2) production upon concanavalin A (Con A) stimulation. Although peripheral CD4+ cells in normal rat highly expressed CD45RC (CD45RChigh), the level of CD45RC expression was low (CD45RClow) in LEC rat peripheral CD4+ cells. However, CD4+ cells from both strains highly expressed CD45 when those cells were stained by pan‐CD45 mAb, suggesting that LEC rat CD4+ cells are deficient in expression of the CD45RC isoform, but not of CD45 molecules. When backcross rats from (F344 × LEC)F1 × LEC were examined, the phenotype for CD45 expression pattern in CD4+ cells was clearly correlated with IL‐2 production level in response to Con A stimulation. Thus, CD45RClow cells exhibit a defect in IL‐2 production, while CD45RChigh cells show normal IL‐2 production. Protein tyrosine phosphatase (PTPase) activity in the membrane fraction of LEC rat CD4+ cells was threefold higher than that of normal rat CD4+ cells. Con A stimulation led to an increase in tyrosine phosphorylation levels, especially 100‐ and 40‐kDa proteins, in normal rat CD4+ cells. In LEC rat CD4+ cells, however, the level of tyrosine phosphorylation in those proteins were very low. These results suggest that an elevated CD45 PTPase activity is responsive for a defect in IL‐2 production in LEC rat peripheral CD4+ T cells.
Both membrane‐bound and soluble forms of CD14 bind to Gram‐negative bacteria
Authors: Jack Robert S. , Grunwald Uwe , Stelter Felix , Workalemahu Grefachew , Schütt Christine 
Published: March 2007

AbstractTissue macrophages and their precursors – the blood monocytes – respond rapidly to a bacterial infection with the release of inflammatory mediators. These mediators are involved in the recruitment of phagocytic cells, principally neutrophils, from the blood to the site of infection. To initiate this process macrophages and monocytes must be able to detect the presence of bacteria in a reliable, but nevertheless nonspecific, fashion. It is thought that this is achieved by means of receptors on the cell surface which recognize structures common to many different bacteria. One candidate for such a “pattern recognition element” is the cell surface glycoprotein CD 14. CD 14 has been shown to bind components of the Gram‐positive cell wall and it also binds soluble lipopolysaccharide released from Gram‐negative bacteria. In both cases the interaction with CD 14 leads to an activation of the cell. Here we show that human peripheral blood monocytes can, in addition, bind intact Gram‐negative bacteria in the presence of serum and that this process involves CD14. When CD14 expression is induced on the myelomonocytic cell line U937 by treatment with vitamin D3 the cells concomittently acquire the capacity to bind bacteria. Furthermore, a non‐monocytic cell line which does not bind bacteria acquires the capacity to do so when transfected with either the human or mouse CD14 gene. This binding can be inhibited by blocking the CD14 receptor with anti‐CD14 antibody or by blocking the ligand on the bacteria with soluble CD14. Finally we demonstrate binding of sCD14 to Escherichia coli. We conclude that in the presence of serum both membrane‐bound and soluble forms of CD14 can bind to Gram‐negative bacteria. This suggests that CD14 may play a role in the detection and elimination of intact bacteria in vivo.
Impaired survival of T cell receptor Vγ3+ cells in interleukin‐4 transgenic mice
Authors: Erb Klaus Joseph , Hanke Thomas , Schimpl Anneliese , Hünig Thomas , Stingi Georg , Elbe Adelheid 
Published: March 2007

AbstractThe mouse epidermis contains a network of Thy‐1+ dendritic T cells. Most of these cells express a homogeneous T cell receptor (TCR) configuration (Vγ3/ Vδ1) with only negligible junctional diversity. Because fetal thymocytes are precursors of these dendritic epidermal T cells (DETC) and the addition of interleukin (IL)‐4 to fetal thymic organ cultures causes an early arrest in thymopoiesis, we examined DETC development in transgenic (tg) mice expressing IL‐4 under the control of major histocompatibility complex class I regulatory sequences. Immunohistologic examination of epidermal sheets and polymerase chain reaction analysis of total skin RNA from IL‐4 tg mice failed to reveal TCR Vγ3+ DETC and Vγ3 mRNA, respectively. In contrast, the sizes of TCR γδ subpopulations in lymphoid organs were unchanged in these mice. Although the numbers and staining intensities of TCR Vγ3+ thymocytes in early fetal (days 14–17) IL‐4 tg mice were similar to those of littermate controls, we observed a preferential death of these cells in thymic organ cultures from IL‐4 tg mice. We observed further that epidermal sheets prepared from 9‐day‐old mice whose mothers had been treated with an IL‐4‐neutralizing antibody from day 12 to day 18 of pregnancy contained DETC numbers similar to those of controls. However, upon termination of the anti‐IL‐4 treatment, DETC ceased to expand. We conclude that IL‐4 impairs the survival of TCR Vγ3+ cells.
Antigen detection in vivo after immunization with different presentation forms of rabies virus antigen: involvement of marginal metallophilic macrophages in the uptake of immune‐stimulating complexes
Authors: Claassen Ivo J. T. M. , Osterhaus Ab D. M. E. , Claassen Eric 
Published: March 2007

AbstractSeveral mechanisms have been postulated to explain the relatively high immunogenicity of antigens presented in immune‐stimulating complexes (iscom). Their potency can in part be explained by the specific targeting of these structures to cells presenting antigens to the immune system. However, until now no method for the subcellular detection of iscom in situ was available. In the present study, a novel, fast and simple method for the detection of iscoms in situ is demonstrated. By making use of the lipophilic fluorescent carbocyanine dyes, 1,1‐dioctadecyl‐3,3,3′,3′‐tetramethylindocarbocyanine perchlorate (Dil) and 3,3′‐dioctadecyloxacarbocyanine perchlorate (DiO), rabies virus antigen and iscom prepared with this antigen were visualized with fluorescence microscopy. The labeled antigen and iscoms were observed in macrophages of spleen and liver of mice within 1–2 h after intravenous administration. When administered intramuscularly or in the footpad, uptake in macrophages of draining lymph nodes could be demonstrated. In the spleen, labeled inactivated virus antigen localized preferentially in the marginal zone macrophages and to a lesser extent in the red pulp macrophages. In contrast, antigen presented in iscom was taken up mainly by the marginal metallophilic macrophages and to a much lesser extend by marginal zone macrophages or follicular‐dendritic and ‐B cells. This method enables the detection of iscom and membrane viruses and allows the analysis of their relation to antigen‐presenting cells in situ. Here, we demonstrate that iscom containing rabies virus antigen are taken up by a subset of macrophages in the spleen distinct from those that take up inactivated rabies virus antigen not presented in iscom, thereby possibly explaining the observed difference in immunogenicity of these antigen preparations. Furthermore, we show a lower efficiency on the induction of humoral and cellular responses after intravenous immunization for both types of antigen when compared with subcutaneous immunization.
Mapping and ranking of potential cytotoxic T epitopes in the p53 protein: effect of mutations and polymorphism on peptide binding to purified and refolded HLA molecules
Authors: Gnjatic Sacha , Paillerets Brigitte Bressac‐De , Guillet Jean‐Gérard , Choppin Jeannine 
Published: March 2007

AbstractIn many cancer cells, the p53 gene displays point mutations that result in stabilization and accumulation of the p53 protein. Therefore, p53 peptides could be presented to the immune system by tumor cells; thus, p53 might be a suitable target antigen for developing an immunotherapy against tumors using cytotoxic T lymphocytes (CTL). To map candidate CTL epitopes, we synthesized 150 peptides of 8–11 residues that contained putative anchor motifs required for binding to common HLA class I molecules. They were tested for their capacity to promote the assembly of purified and refolded HLA‐A1, A2, B7 and B8 molecules. The following wild‐type p53 peptides were found to be reactive with the HLA molecules tested: 196–205 and 226–234 bound moderately to HLA‐A1; 25–35, 65–73, 129–137, 187–197, 263–272 and 264–272 bound strongly, and 187–195 and 256–264 moderately to HLA‐A2; 26–35, 63–73, 189–197, 249–257 and 321–330 bound strongly to HLA‐B7; and 135–143, 210–218 and 375–383 bound weakly to HLA‐B8. We also analyzed the effects of p53 mutations occurring naturally in tumors on peptide/HLA assembly. We found substitutions that enhanced, diminished or had no effect on the peptide binding to HLA molecules. Polymorphism at position 72 mainly affected peptide/HLA‐B7 binding, the proline allele P72 giving a less‐reactive peptide (63–73) than the arginine allele R72. We have ranked potential p53 epitopes according to their reactivity for purified HLA molecules, allowing the selection of appropriate peptides and HLA molecules to attempt CTL induction in vitro.
Heterogeneity of rat encephalitogenic T cells elicited by variants of the myelin basic protein (68–86) peptide
Authors: Sun Deming , Coleclough Christopher , Hu Xian‐Zhen 
Published: March 2007

AbstractBy immunizing Lewis rats with myelin basic protein (MBP) peptide variants derived from the major encephalitogenic epitope of guinea pig (MBP(68–88) and then isolating encephalitogenic T cells from these animals, we demonstrated that the variant peptides do not elicit the same encephalitogenic T cell subsets as those induced by the wild‐type peptide or by intact MBP. Rather, the pathogenic T cells differed in clonal composition as reflected by their heterogeneous responses to a panel of variant peptides and by their T cell receptor usage. Thus, molecules mimicking the MBP(68–88) autoantigen can elicit pathogenic T cell subsets without necessarily cross‐reacting with T cells specific for the original autoantigen. This suggests that a more clonally diverse group of pathogenic T cells might be involved in EAE than has been apparent from studies with intact MBP or its unaltered peptides.
Involvement of cAMP in CD3 T cell receptor complex‐ and CD2‐mediated apoptosis of human thymocytes
Authors: Mentz Frank , Mossalayi M. Djavad , Ouaaz Fateh , Debré Patrice 
Published: March 2007

AbstractDuring intrathymic T cell development, elimination of autoreactive T cell clones by programmed cell death (PCD or apoptosis) is an essential mechanism for self tolerance. The precise intracellular second messengers that lead to this process remain to be determined. In the present work, we show that treatment of freshly isolated thymocytes with an antagonist of the cAMP pathway, the Rp‐cAMP, significantly decreases spontaneous death by apoptosis of human thymocytes in vitro. Addition of Rp‐cAMP also rescues thymocytes from activation‐induced apoptosis following the ligation of surface CD3/T cell receptor complex or CD2 antigens. A cAMP analog, the dibutyryl(Dibut)‐cAMP increases PCD of human thymocytes in a dose‐dependent manner. Growth and rescue from PCD of thymocytes in the presence of interleukin (IL)‐2 or IL‐4 are also enhanced by Rp‐cAMP and inhibited by Dibut‐cAMP. Finally, we detect substantial levels of intracellular cAMP in freshly isolated thymocytes. This study reveals the involvement of cAMP as a second messenger during the apoptosis of normal human thymocytes.
The influence of invariant chain on the positive selection of single T cell receptor specificities
Authors: Tourne Sylvie , Nakano Naoko , Viville Stéphane , Benoist Christophe , Mathis Diane 
Published: March 2007

AbstractThe appearance of peptide‐loaded major histocompatibility complex (MHC) class II molecules at the cell surface depends critically on the invariant chain (Ii). We have studied the influence of Ii on the positive selection of CD4+ T cells, mediated by class II molecules expressed on thymic stromal cells. Invariant chain‐deficient mice (Ii°) were crossed with different T cell receptor (TcR) transgenic strains and the emergence of mature CD4 single‐positive thymocytes measured in Ii°/TcR transgenic offspring. Positive selection was nearly absent in Ii°/2B4 mice, which display receptors specific for a moth cytochrome c (MCC) peptide in the context of Ek. In addition, no T cell response was elicited when nontransgenic Ii° animals were injected with this peptide, even though antigenpresenting cells (APC) from such mice were perfectly capable of presenting it, suggesting that selection of the entire anti‐MCC 88‐103 repertoire depends on Ii. Positive selection also appeared strongly reduced in another line of Ii°/TcR transgenic mice (Ii°/BDC2.5). However, in sharp contrast, a third line (Ii°/3A9) exhibited almost normal positive selection of thymocytes displaying the transgene‐encoded receptor. These thymocytes were exported to the periphery; peripheral T cells could respond normally to the appropriate peptide in vitro. The most likely interpretation of these findings is that selection of most CD4+ T cells depends on MHC class II complexes loaded with peptide in an Ii‐dependent pathway, but some can be selected on class II complexes that are either loaded along an alternative, Ii‐independent, route or are empty. This is consistent with the involvement of peptide in positive selection of CD4+ T cells, for which there exists little prior evidence.
Rearrangement of upstream DH and VH genes to a rearranged immunoglobulin variable region gene inserted into the DQ52‐JH region of the immunoglobulin heavy chain locus
Authors: Taki Shinsuke , Schwenk Frieder , Rajewsky Klaus 
Published: March 2007

AbstractWe investigated gene rearrangements in the mutant IgH locus of a mouse strain generated by insertion of a rearranged heavy chain variable region gene (VT15) into the DQ52‐JH region through gene targeting. In more than half of the B cells of heterozygous mutant mice, the mutant IgH locus was silenced by the rearrangement of an endogenous DH or DH and VH gene to the inserted VT15 gene. In these cases, a functional VHDHJH gene was present on the wild‐type allele. The silencing rearrangement appeared to be mediated by recombination signal sequence (RSS)‐like elements present in the “recipient” VT15 gene. Among the many such elements on the inserted VT15 gene, which apparently met the requirement for an RSS with respect to nucleotide sequence, only two were observed in the actual rearrangements. This indicates that targeting of the recombination machinery involves sequences in addition to the RSS motifs as they have been characterized so far. In homozygous mutant mice, most B cells appeared to carry the intact VT15 gene on both mutant IgH alleles, although single‐cell polymerase chain reaction revealed that silencing rearrangements occured frequently in B cell progenitors in the bone marrow. This observation indicates that once silencing rearrangements are initiated in a cell, they involve both VT15 genes in most cases, reminiscent of normal DH‐JH rearrangement. B cells which did not initiate such rearrangements develop to populate the peripheral B cell compartment.
Sphingomyelin‐ceramide turnover in CD28 costimulatory signaling
Authors: Chan Gordon , Ochi Atsuo 
Published: March 2007

AbstractWhen the CD28 membrane glycoprotein of T cells binds to its ligand, a signal is transmitted that is required for T cell receptor‐induced proliferation and cytokine secretion; T cells are not stimulated by the CD28 signal alone. Ligation of CD28 initiated sphingomyelin hydrolysis and generated ceramide. Treatment of T cells with either exogenous sphingomyelinase or a cell‐permeable ceramide analogue, C6‐ceramide, mimicked the CD28 signal by inducing T cell proliferation and interleukin‐2 gene transcription. Stabilization of interleukin‐2 mRNA was also observed in C6‐ceramide‐treated cells. Thus, the sphingomyelin‐ceramide pathway is a candidate for mediating the costimulatory signal.
Association of the transmembrane 4 superfamily molecule CD53 with a tyrosine phosphatase activity
Authors: Carmo Alexandre M. , Wright Mark D. 
Published: March 2007

AbstractCell surface proteins of the transmembrane 4 superfamily (TM4SF) are a newly characterized family of proteins which are presumed to span the plasma membrane four times. The function of this family of molecules is poorly understood, but based on monoclonal antibody studies there is some evidence that they may be involved in transmembrane signal transduction and regulation of cell proliferation, differentiation, or both, in a number of different cell types. CD53 is a member of this family that is expressed on leukocytes, and transduces activation signals through unknown mechanisms that may involve phosphorylation events. However, CD53 has never been shown to associate directly with kinases. Here, we show by immunoprecipitation from cell lysates of lymph nodes and a thymoma cell line, that immune complexes of rat CD53 contain tyrosine phosphatase activity. The CD53‐associated phosphatase was able to dephosphorylate in vitro the phosphorylated tyrosine kinase Lck, as well as a synthetic substrate, and its activity was abrogated by a tyrosine phosphatase inhibitor. Although its identity has not been established, it is clear from depletion experiments that it is not CD45. CD63, a second member of the TM4SF, also co‐precipitates a phosphatase activity from rat basophilic leukemia cells. These results demonstrate that the TM4SF members associate with tyrosine phosphatases. It seems possible that such associated phosphatases may contribute to the signal transduction capacity of TM4SF molecules.
Differential contribution of the FcRγ chain to the surface expression of the T cell receptor among T cells localized in epithelia: analysis of FcRγ‐deficient mice
Authors: Park Seung Yong , Arase Hisashi , Wakizaka Keisuke , Hirayama Nakami , Masaki Shigehiro , Sato So‐Ichiro , Ravetch Jeffrey V. , Saito Takashi 
Published: March 2007

AbstractThe function of the Fc receptors γ chain (FcRγ) for the expression of the T cell receptor (TCR) complex and for T cell development, especially for T cells localized in epithelia, was investigated by analyzing FcRγ‐deficient mice. In wildtype mice, CD8αα+β−TCRαβ+ T cells of intestinal intraepithelial lymphocytes (i‐IEL) utilized CD3ζ homodimers and ζ‐FcRγ heterodimers, whereas CD8α α+β−TCRγδ+ i‐IEL used ζ‐FcRγ and FcRγ homodimers in the TCR complex. On the other hand, these T cells in FcRγ‐deficient mice contained only ζ homodimers. The surface expression of the TCR complex was reduced in CD8αα+β−i‐IEL and dendritic epidermal T cells (DETC) in these mice, whereas the development of these T cells was normal. The degree of reduction appeared to depend on the expression level of FcRγ. In contrast to these populations, TCRγδ+ intraepithelial T cells in reproductive organs (r‐IEL) were dramatically decreased, suggesting that the development of r‐IEL is FcRγ‐dependent, probably due to the predominant usage of FcRγ homodimers in the TCR complex. These results indicate that the FcRγ chain contributes differently to the TCR expression and to the development of T cells localized in epithelia.
Differences in processing of an autoantigen by DR4:Dw4.2 and DR4:Dw14.2 antigen‐presenting cells
Authors: Nicolle Michael W. , Hawke Simon , Willcox Nicholas , Vincent Angela 
Published: March 2007

AbstractVariations in antigen processing can influence class II‐restricted T cell responses. We now report a highly significant difference (p < 0.001) between the ability of antigen‐presenting cells from three HLA‐DR4:Dw14.2 (Arg71) and six DR4:Dw4.2 (Lys71) individals to present recombinant or native acetylcholine receptor antigens to a myasthenia gravis T cell clone. The difference was greatest with longer antigens, and not seen with short synthetic peptides, suggesting that it may result from a difference in antigen processing between the two alleles. The results were not related to the presence of myasthenia gravis or of steroid therapy. They could, however, be of relevance in rheumatoid arthritis where particularly severe disease associates with Dw4.2/Dw14.2 heterozygosity.
Establishment of a cell line with features of early dendritic cell precursors from fetal mouse skin
Authors: Girolomoni Giampiero , Lutz Manfred B. , Pastore Saveria , Aßmann Caroline U. , Cavani Andrea , Ricciardi‐Castagnoli Paola 
Published: March 2007

AbstractDuring ontogeny, the skin is progressively populated by major histocompatibility complex class II‐negative dendritic cell (DC) precursors that then mature into efficient antigen‐presenting cells (APC). To characterize these DC progenitors better, we generated myeloid cell lines from fetal mouse skin by infecting cell suspensions with a retroviral vector carrying an envAKR‐mycMH2 fusion gene. These cells, represented by the line FSDC, displayed a dendritic morphology and their proliferation in serum‐free medium was promoted by granulocyte/macrophage colony‐stimulating factor (GM‐CSF), but not macrophage‐CSF. FSDC expressed strong surface‐membrane ATP/ADPase activity, intracellular staining for 2A1 antigen, and a surface phenotype consistent with a myeloid precursor: H‐2d.b+, I‐Ad.b+, CD54+, CD11b+, CD11c+, 2.4G2+, F4/80+, CD44+, 2F8+, ER‐MP 12−, Sca‐1+, Sca‐2+, NLDC‐145−, B7.2+, B7.1−, J11d−, B220−, Thy‐1−, and CD3−. FSDC stimulated poorly allogeneic or syngeneic T cells in the primary mixed‐leukocyte reaction, and markedly increased this function after treatment with GM‐CSF, GM‐CSF and interleukin (IL)‐4 or interferon‐γ (IFN‐γ); in contrast, stem cell factor, IL‐1α and tumor necrosis factor‐α had no effect. Preculture with IFN‐γ was required for presentation of haptens to primed T cells in vitro. However, FSDC, even after cytokine activation, were less potent APC than adult epidermal Langerhans cells in both of the above assays. Finally, FSDC derivatized with haptens and injected either intravenously or subcutaneously could efficiently induce contact sensitivity responses in naive syngeneic mice. The results indicate that fetal mouse skin is colonized by myeloid precursors possessing a macrophage/immature DC‐like surface phenotype and priming capacity in vivo. These cells need further differentiation and activation signals (e.g. cytokines) to express their antigen presenting potential in vitro.