bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcriptional regulation of interleukin‐2 gene expression by CD69‐generated signals
Authors: D'Ambrosio Daniele , Trotta Rossana , Vacca Alessandra , Frati Luigi , Santoni Angela , Gulino Alberto , Testi Roberto 
Published: March 2007

AbstractThe 5′ flanking region of the human interleukin (IL)‐2 gene was investigated for enhancer activity in response to CD69‐generated signals, using a chloramphenicol acetyltransferase (CAT)‐driven transient expression system in Jurkat cells. The region extending from −317 to +47 relative to the initiation site of IL‐2 gene transcription was shown to contain sequences able to respond to CD69 cross‐linking, by enhancing by about 100 % a phorbol 12‐myristate 13‐acetate (PMA)‐plus‐ionomycin stimulation of CAT activity. A similar increase in CAT activity produced by PMA‐plus‐anti‐CD3 mAb was induced by CD69 cross‐linking, while a 200 % increase over that obtained by PMA‐plus‐anti‐CD28 mAb stimulation was seen. Analysis of enhancer deletion mutants revealed that proximal AP‐1, OCT‐1/octamer‐associated protein and nuclear factor of activated T cells (NFAT) binding regions were all necessary to allow CD69‐mediated enhancement of CAT activity. By gel mobility shift analysis, cyclosporin A‐sensitive NFAT‐binding induction and enhancement of AP‐1 binding activity could be detected in nuclear extracts of both Jurkat and peripheral blood T cells after simultaneous CD69 and protein kinase C stimulation. Finally, CD69‐mediated signals could increase NFAT and AP‐1 binding activity following PMA and ionomycin stimulation in peripheral blood T cells. Collectively, these data suggest that CD69‐generated signals participate in the control of the IL‐2 gene expression at the transcriptional level, likely acting through NFAT and AP‐1 transcription factor complexes.
A soluble form of the adhesion receptor CD58 (LFA‐3) is present in human body fluids
Authors: Hoffmann Jörg C. , Dengler Thomas J. , Knolle Percy A. , Albert‐Wolf Marion , Roux Matthias , Wallich Reinhard , Meuer Stefan C. 
Published: March 2007

AbstractThe human adhesion receptor CD58 (LFA‐3) is expressed on most human cell types. Here we report on a soluble form of CD58 (sCD58) in human serum, human urine, and culture supernatants of several cell lines. sCD58 partially purified from human serum, from supernatant of the Hodgkin cell line L428, and purified sCD58 from human urine were found to have a molecular mass of 40‐70 kDa under denaturating conditions (sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and Western blotting). However, gel filtration of sCD58 purified from human urine gave a molecular mass of 118‐166 kDa, suggesting a noncovalent homotrimer conformation or its association with other molecules. Using an enzyme‐linked immunosorbent assay specific for CD58 we found that sera from patients suffering from different forms of hepatitis contained elevated sCD58 levels (n = 108). Accordingly, there was a fivefold increase of supernatant sCD58 when the hepatocellular carcinoma cell line Hep G2 was incubated with 25 ng/ml recombinant tumor necrosis factor‐α in vitro. In contrast, sCD58 serum levels of 337 additional patients suffering from various other immunological disorders were not found to be raised. At high concentrations sCD58 binds to CD2‐positive cells and inhibits rosette formation of human T cells to human erythrocytes. Thus, local release of large quantities of naturally occurring sCD58 may interfere with intercellular adhesion in vivo.
Analysis of tetanus toxin peptide/DR recognition by human T cell receptors reconstituted into a murine T cell hybridoma
Authors: Blank Ulrich , Boitel Brigitte , Mège Dominique , Ermonval Myriam , Acuto Oreste 
Published: March 2007

AbstractWe have previously reported that human T cell receptors (TcR) selected in the class II‐restricted (HLA‐DRB1*1302) response to a tetanus toxin peptide (tt830‐843) frequently used the Vβ2 germ‐line segment which paired with several Vα segments and that the putative CDR3 of both α and β chains showed remarkable heterogeneity. To analyze the structural basis for recognition of the tt830‐843/DR complex, five of these TcR were reconstituted into a murine T cell hybridoma, 58 α−β−, by expressing the human α and β variable regions joined to the mouse α and β constant regions, respectively. The chimeric TcR, expressing the same Vβ germ‐line segment (Vβ2), two expressing Vα21.1, twoVα17.1 and one Vα8.1 were shown to have the expected antigen specificity and DR restriction.Two lines of evidence suggested that the putative CDR3, although not conserved in these TcR, played a key role in recognition. First, two TcR with identical V germ‐line segments but distinct CDR3 showed large differences in their capacity to react with the ligand. Second, interchanging the α and β chains from tt830‐843/DR1302‐specific TcR which differed in their CDR3 sequences invariably led to loss of recognition. We also asked whether germ‐line Vα17.1 could functionally replace Vα21.1, as they appear to be related in their primary sequence. However, as in the case of CDR3 exchanges, Vα replacement abrogated TcR reactivity. Taken together, these data underline the fine interdependence of the structural components of the TcR binding site in defining a given specificity.Four of the TcR studied displaying promiscuous recognition were also tested against different DR alleles and site‐directed mutants. The results of these experiments suggested that, in spite of their structural heterogeneity, anti‐tt830‐843 TcR may have a similar orientation with respect to the peptide/DR complex.The reconstitution system described herein should represent a valuable tool for detailed studies of human TcR specificity.
Continuous in vivo activation and transient hyporesponsiveness to TcR/CD3 triggering of human gut lamina propria lymphocytes
Authors: de Maria Ruggero , Fais Stefano , Silvestri Maurizio , Frati Luigi , Pallone Francesco , Santoni Angela , Testi Roberto 
Published: March 2007

AbstractThree‐color immunofluorescence and flow cytometric analysis showed that the vast majority of normal human T‐lamina propria lymphocytes (LPL) expressed high levels of the early activation antigen CD69, together with CD45R0, irrespective of their CD4, CD8 or γ/δ‐TcR phenotype, indicating that they are continuously stimulated in vivo. Importantly, measurement of cytoplasmic [Ca2+]i showed that T‐LPL had significantly higher basal [Ca2+]i levels, compared to autologous peripheral blood lymphocytes (PBL). Both cytoplasmic [Ca2+]i elevation and inositol (1, 4, 5) trisphosphate generation following CD3 cross‐linking by monoclonal antibodies in vitro were essentially abolished in T‐LPL, as compared to autologous T‐PBL. Moreover, freshly isolated LPL could be induced to proliferate by CD2‐ or CD28‐mediated signals, but not by CD3‐mediated signals. Surprisingly however, impairment in TcR/CD3‐mediated early signaling and proliferation in T‐LPL could be completely reversed by 24 h incubation of the cells at 37 °C in culture medium, a condition which allowed basal intracellular [Ca2+]i to return to levels comparable to peripheral T cells.Our data suggest that selective hyporesponsiveness to TcR/CD3‐mediated signaling may represent a transient event during continuous in vivo activation of mucosal lymphocytes.
The mitogenic response of T cells to interleukin‐2 requires Raf‐1
Authors: Riedel Detlev , Brennscheidt Ulrich , Kiehntopf Michael , Brach Marion , Herrmann Friedhelm 
Published: March 2007

AbstractThe product of the c‐raf‐1 proto‐oncogene, Raf‐1, is known to encode a 74‐kDa ubiquitously expressed cytoplasmic serine/threonine kinase. Various growth factors such as epidermal growth factor, acidic fibroblast growth factor, platelet‐derived growth factor, insulin, granulocyte‐macrophage colony‐stimulating factor, interleukin (IL)‐2, IL‐3 and erythropoietin have been shown to induce phosphorylation of Raf‐1, thereby activating Raf‐1 kinase. Raf‐1 is, thus, believed to play a role in coupling growth factor receptors to proliferation. We have examined the role of Raf‐1 in the mitogenic response of human peripheral blood‐derived IL‐2 receptor expressing T cells to human recombinant IL‐2 employing c‐raf antisense (AS) oligodeoxyribonucleotide. Uptake studies of oligonucleotides indicated that incorporation of oligomers was maximal at 4 h and oligdeoxynucleotides remained stable in these cells for up to 24 h. Treatment of T cells with the AS oligodeoxyribonucleotide in intracellular duplex formation followed by efficient translation blockade of c‐raf‐1. In contrast, sense (S) and nonsense (NS) oligodeoxynucleotides failed to form intracellular duplexes and did not interfere with translation of c‐raf‐1, suggesting specific elimination of c‐raf‐1 by the AS oligomer. Proliferation of T cells ([3H]thymidine incorporation) following exposure to IL‐2 was substantially reduced when the c‐raf‐1 AS oligodeoxyribonucleotide was added to cultures, while the mitogenic response to this factor remained almost unaffected in the presence of S and NS oligodeoxy‐ribonucleotides.
Major histocompatibility complex class II‐restricted presentation of secreted and endoplasmic reticulum resident antigens requires the invariant chains and is sensitive to lysosomotropic agents
Authors: Humbert Martine , Bertolino Patrick , Forquet Frédérique , Rabourdin‐Combe Chantal , Gerlier Denis , Davoust Jean , Salamero Jean 
Published: March 2007

AbstractWe have tested the involvement of the invariant chains (Ii) p31 and p41 in the presentation of peptides derived from hen egg lysozyme (HEL) constructs targeted to different intracellular compartments within transfected fibroblasts. The endogenous HEL constructs were either present in the cytosol (HELc), secreted (HELs), or linked to the mammalian (KDEL C‐terminal sequence that causes retention of HEL in the endoplasmic reticulum (ER)/pre‐Golgi recycling compartment (HELr). Using Ii‐negative antigen‐presenting cells, the presentation of HELr to a HEL 46‐61 specific T cell hybridoma was far less efficient than the presentation of the HELs. High levels of Ii expression enhanced drastically the presentation of the HEL 46‐61 determinant derived from both HELr and HELs. HELr and HELs presentation was fully sensitive to lysosomotropic agents such as chloroquine, indicating that the formation of complexes between major histocompatibility complex (MHC) class II molecules and determinants derived from endogenous antigens entering the secretory pathway is taking place in an acidic compartment. The degradation and dissociation of Ii might be a prerequisite for the efficient presentation of endogenously derived determinants by MHC class II molecules, as for the presentation of most exogenous antigens. All our results are compatible with the notion that endogenous molecules being translocated into the lumen of the ER could be presented by class II molecules through a processing pathway involving an acidic compartment in which Ii chains dissociate from class II molecules.
Selection of internalization‐deficient cells by interleukin‐2‐Pseudomonas exotoxin chimeric protein: the cytoplasmic domain of the interleukin‐2 receptor β chain does not contribute to internalization of interleukin‐2
Authors: Furse Robert K. , Malek Thomas R. 
Published: March 2007

AbstractTo study the structural basis of ligand‐induced receptor‐mediated internalization of interleukin‐2 (IL‐2), a strategy has been developed to generate variant T cells that are deficient in internalization of this cytokine. IL‐2 receptor (IL‐2R) α‐ and β‐bearing EL4 cells, that express high‐affinity IL‐2R and internalize IL‐2, were treated with low doses of IL‐2‐Pseudomonas exotoxin chimeric protein (IL‐2‐PE40). This treatment resulted in isolation of a variant (CX1) that was unable to express high‐affinity IL‐2R or internalize IL‐2. Transfection of CX1 with the IL‐2Rβ cDNA led to surface expression of IL‐2Rβ and high‐affinity IL‐2R as well as the ability to internalize IL‐2. This finding indicates that the absence of the p subunit was the sole defect in CX1 responsible for its failure to internalize IL‐2. By transfecting CX1 with mutated β cDNA, several CX1 transfectants were produced that expressed a β‐subunit that lacked all amino acids of the intracytoplasmic region. These transfectants expressed high‐affinity IL‐2R and internalized IL‐2 at a rate comparable to cells expressing wild‐type β‐chain. These results demonstrate that internalization of IL‐2 is independent of any signals contained in the intracytoplasmic tail of the β subunit and raise the possibility that such signals may be entirely contained within the γ subunit.
HLA class II molecule‐mediated signal transduction mechanism responsible for the expression of interleukin‐1β and tumor necrosis factor‐α genes induced by a staphylococcal superantigen
Authors: Matsuyama Satoru , Koide Yukio , Yoshida Takato O. 
Published: March 2007

AbstractSuperantigens including staphylococcal enterotoxins (SE) bind to major histocompatibility complex class II molecules and interact with T cells bearing particular vβ chains. SEB was shown to induce the expression of interleukin (IL)‐1β and tumor necrosis factor (TNF)‐α genes in human peripheral blood monocytes bearing HLA class II molecules. Monoclonal antibodies directed against HLA‐DR and ‐DQ abolished the SEB‐induced expression of both the EL‐1β and TNF‐α genes, suggesting that the HLA class II molecules mediated the gene expression. Therefore, we investigated the signal transduction mechanism responsible for the expression of IL‐1β and TNF‐α genes induced by binding of SEB to the HLA class II molecules. Three protein tyrosine kinase (PTK) inhibitors, genistein, herbimycin A., and tyrphostin, each of which has a different mechanism of action, strongly inhibited the expression of the monokine mRNA induced by SEB. Analyses of PTK activity revealed that SEB induced a rapid increase of membrane‐associated PTK activity and this was blocked by tyrphostin. Furthermore, H‐7 inhibited the expression of the monokine mRNA induced by SEB, suggesting the involvement of protein kinase C (PKC) in the signaling pathway. The involvement of PKC was confirmed by the observations that phorbol 12‐myristate 13‐acetate (PMA), a direct activator of PKC, induced the expression of the monokine mRNA and that SEB evoked the activation of membrane‐associated PKC. Both activation of PKC and expression of the monokine mRNA induced by SEB appeared to be inhibited by tyrphostin, but those induced by PMA were not. Taken together, these findings indicate that both PTK and PKC play essential roles in HLA class II molecule‐mediated signal transduction elicited by SEB and that PTK activation may precede PKC activation in the signaling pathway.
Half‐life of antigen/major histocompatibility complex class II complexes in vivo: intra‐ and interorgan variations
Authors: Müller Klaus‐Peter , Schumacher Jochen , Kyewski Bruno A. 
Published: March 2007

AbstractWe have determined the half‐life in vivo of antigen/MHC class II complexes in different organ microenvironments. Mice were “pulsed” with myoglobin intravenously and MHC class II‐positive antigen‐presenting cell (APC) populations from different organs were isolated after various time intervals. Specific antigen/MHC complexes were quantitated by co‐cultivation of the APC subsets with myoglobin‐specific T‐T hybridoma cells in vitro. Half‐lives of antigen/MHC complexes differed both between organs and between compartments of the same organ. Half‐lives in peripheral organs (spleen and bone marrow) ranged between 3 and 8 h, whereas in the thymus half‐lives between 13 h (cortical epithelial cells) and 22 h (medullary dendritic cells) were observed. Half lives in vivo were independent of antigen processing, since intact protein or antigenic peptides yielded similar values. The considerably longer half‐life of peptide/MHC complexes in the thymus as compared to peripheral organs may reflect the distinct role which antigen presentation plays in both organs, i.e. induction of tolerance versus induction of immunity.
Switching capacity of FcϵRII‐positive and ‐negative murine B cells
Authors: Foy Teresa M. , Waldschmidt Thomas J. 
Published: March 2007

AbstractIn previous studies, our laboratory demonstrated the utility of the low affinity IgE Fc receptor (FcϵRII) in delineating a number of murine B cell subsets. In the spleen, the FcϵRII is expressed on mature conventional B cells but is absent on marginal zone B cells. In the peritoneal cavity, the receptor is present on all conventional B cells, but is not expressed on fresh peritoneal Ly1/sister B cells. The studies in this report compared the ability of these B cell poputations to isotype switch. Using a lipopolysaccharide (LPS)‐ and interleukin (IL)‐4‐driven system, sort‐purified FcϵRII‐ positive and ‐negative B cells from peritoneum and spleen were tested for switching to IgG1, IgE, and IgA. The results demonstrated that regardless of their source, FcϵRII+ B cells produced significant levels of IgG1 and IgE. Similar results were obtained with FcϵRII− (marginal zone) B cells obtained from spleen. In contrast, FcϵRII− (Ly1/sister) peritoneal B cells were found to produce IgG1 and IgA, but were incapable of secreting significant levels of IgE. Further studies tested for LPS and IL‐4‐induced expression of FcϵRII and Thy1 on the various B cell populations. These experiments demonstrated the induction of the FcϵRII on all B cells, regardless of their initial resting levels. Additionally, Thy1 was found to be induced only on those B cell subsets capable of producing IgE. Taken together, the results demonstrate a correlation between IgE secretion and Thy1 expression, and no apparent correlation between the presence of the FcϵRII and isotype commitment.
Peripheral clonal deletion of antiviral memory CD8+ T cells
Authors: Moskophidis Demetrius , Laine Elisabeth , Zinkernagel Rolf M. 
Published: March 2007

AbstractAntiviral cytotoxic memory CD8+ T cells adoptively transferred to mice which are persistently infected with lymphocytic choriomeningitis virus WE or DOCILE initially proliferated extensively; they either caused the death of the recipient or, alternatively, disappeared within a few days. Apparently, the complete and coordinated induction and stimulation by widely distributed viral antigen caused these memory T cells to die before virus had been eliminated from the host. Thus memory T cells are as susceptible to peripheral exhaustion/deletion as unprimed T cells. These results indicate possible limitations of exclusively CD8+ T cell‐mediated adoptive immunotherapy against viral infections or tumors.
Elevated levels of T cell activation antigen CD27 and increased interleukin‐4 production in human lymphatic filariasis
Authors: Yazdanbakhsh Maria , Sartono Erliyani , Kruize Yvonne C. M. , Kumiawan Agnes , van der Pouw‐Kraan Tineke , van der Meide Peter H. , Selkirk Murray E. , Partono Felix , Hintzen Rogier Q. , van Lier René A. W. , Maizels Rick M. 
Published: March 2007

AbstractTo assess the immunological changes occurring during filarial infection with or without elephantiasis, 145 patients in different clinical groups from an endemic area in Indonesia were compared with respect to plasma levels of both soluble CD25 (sCD25) and sCD27; interleukin‐4 (IL‐4) and interferon‐γ release by peripheral blood mononuclear cells was also measured in a smaller subset of individuals. Levels of sCD27 were significantly elevated in elephantiasis and microfilaremic patients compared with endemic normals (p < 0.002), whereas sCD25 levels remained low in microfilaremics and was only slightly elevated in elephantiasis patients compared with endemic normals (p <0.02). As activated T cell populations release both sCD27 and sCD25, these findings imply that there is filarial‐driven activation of a Tcell subset that releases sCD27 rather than sCD25. The expansion of a particular Tcell population by filarial parasites is further suggested by the enhancement in both IL‐4‐producing and CD4+CD27−T cells in PBMC from elephantiasis and microfilaremic patients compared with endemic normals. More detailed characterization and comparison of CD27− lymphocytes from these individuals may identify mechanisms involved in the pathogenesis of lymphatic filariasis.
Identification of conserved T cell receptor CDR3 residues contacting known exposed peptide side chains from a major histocompatibility complex class I‐bound determinant
Authors: Kelly Janice M. , Sterry Sandra J. , Cose Stephen , Turner Stephen J. , Fecondo John , Rodda Stuart , Fink Pamela J. , Carbone Francis R. 
Published: March 2007

AbstractWe have analyzed the T cell receptor (TCR) repertoire found in the major histocompatibility complex class I‐restricted cytotoxic T lymphocyte (CTL) response to the protein ovalbumin (OVA). Despite skewing towards the expression of Vβ5.2+ TCR by OVA‐specific CTL from C57BL/6 mice, we found a relatively high degree of diversity in V(D)J usage in both TCR α‐ and β‐chains. Closer examination showed that the majority of these sequences encoded negatively and positively charged residues at their respective TCR α‐ and β‐chain VJ or VDJ junctions. These junctions form the third complementarity‐determining regions (CDR3) of the TCR polypeptides involved in the direct interaction with the class I‐bound peptide. Crystallographic analyses of Kb‐peptide complexes predict that the major determinant from OVA, peptide OVA257–264 (SIINFEKL), contains two exposed charged side chains which can contact the TCR. These are the negatively charged glutamic acid at determinant position 6 (P6) and the positively charged lysine at P7. To examine whether the TCR α‐chain makes contact with P7 lysine, we established a single chain TCR transgenic C57BL/6 mouse line where all T cells express a TCR β‐chain derived from the Vβ5.2+ clone B3. OVA‐specific T cells derived from in vivo primed transgenic mice preferentially expressed TCR α‐chains that also contained negatively charged junctional residues despite some further variation in Vα and Jα sequences. Stimulation of naive TCR β‐chain transgenic T cells with a P7 substitution peptide analogue induced a T cell response that was no longer cross‐reactive with the wild‐type OVA257–264 determinant, sugesting that the TCR α‐chain from the T cell clone B3 can determine the specificity for this residue. Consequently, these results reveal the existence of conserved residues in the CDR3 of TCR α‐ and β‐chains specific for OVA257–264 and identify their possible orientation over the peptide‐class I complex.