bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation between ribosylation of pertussis toxin substrates and inhibition of peptidoglycan‐, muramyl dipeptide‐ and lipopolysaccharide‐induced mitogenic stimulation in B lymphocytes
Authors: Dziarski Roman 
Published: March 2007

AbstractSelective inhibition by pertussis toxin (PT) of mitogenic activation of mouse B lymphocytes by bacterial mitogens (peptidoglycan and lipopolysaccharide) and muramyl dipeptide (a synthetic analog of peptidoglycan fragment) was demonstrated. Mitogenic activation of B cells by protein kinase C activators and ionomycin was insensitive to PT. Also PT did not inhibit peptidoglycan‐ and lipopolysaccharide‐induced differentiation of B cells into Ig‐secreting cells, when it was added to the cultures after the proliferative stage of the response. B lymphocyte membranes contained two major PT substrates (40 and 41 kDa). The extent of PT‐mediated ADP ribosylation of these substrates correlated with the degree of PT‐mediated inhibition of mitogenic stimulation of B cells. B cell stimulation by all mitogens tested was not inhibited by cholera toxin at nontoxic concentrations that are known to cause maximal increase in cAMP in B cells. Since the only known substrates for PT‐mediated ADP ribosylation in mammalian cells are the α subunits of some G proteins, our data suggest that G proteins are present in B cell membranes and that they are involved in B cell activation induced by bacterial mitogens.
Regulation of interleukin 2 gene expression: discrepancy between enhancer activity and endogenous gene expression
Authors: Mårtensson Inga‐Lill , Leanderson Tomas 
Published: March 2007

AbstractA 630‐bp fragment of the human interleukin 2 (IL 2) promoter (+ 51 to ‐584) permitted expression of a reporter gene transfected into a mouse T cell lymphoma line (EL4) upon induction with phorbol ester. In contrast, when a human T cell lymphoma (Jurkat) was transfected with the same plasmid and subsequently induced with phorbol ester together with phytohemagglutinin, a very low expression of the transfected gene was observed. The endogenous IL 2 gene was equally well expressed in both cell lines upon induction. Thus, the expression of the endogenous and the transfected gene did not correlate in Jurkat cells. An SV 40 enhancer element cloned 5′ of the IL 2 promoter did not result in constitutive expression after transfection to either cell line, rather the IL 2 promoter retained the need for induction. The addition of an enhancer element increased the induced expression of the transfected gene in Jurkat cells into proximity of that observed in induced EL4 cells, indicating that additional sequence elements not contained in the 630‐bp fragment are needed for proper expression of the IL 2 gene in Jurkat cells.
Expression of cytoplasmic granules with T cell‐associated serine proteinase‐1 activity in Ly‐2(CD8) T lymphocytes responding to lymphocytic choriomeningitis virus in vivo
Authors: Kramer Michael D. , Fruth Uli , Simon Hans‐Georg , Simon Markus M. 
Published: March 2007

AbstractMonoclonal antibodies (mAb) with specificity for the T cell‐associated serine proteinase‐1 of the mouse (MTSP‐1) were used to study expression and storage of this enzyme in T lymphocytes during lymphocytic choriomeningitis (LCM) virus infection in vivo. Immunohistochemical analysis of splenic tissue at the peak of LCM virus‐specific T cell‐mediated cytolytic responses, i.e., at day 7 post infection, revealed high numbers of MTSP‐1 T lymphocytes in the interfollicular T cell‐dependent area of the spleen. More than 50% of Ly‐2(CD8) cells but only low numbers of Ly‐2‐(CD8‐) cells, previously enriched by flow cytofluorometry, contained large amounts of cytoplasmic granules which stained both with MTSP‐1‐specific mAb and the esterase substrate N‐α‐benzyloxycarbonyl‐L‐lysine thiobenzyl ester. These data demonstrate that in vivo generated LCM virus‐induced cytolytic T lymphocytes develop cytoplasmic storage granules containing MTSP‐1 and suggest that the mechanism of granule exocytosis is operative in vivo; possibly MTSP‐1 is one effector molecule participating in the Ly‐2(CD8) T lymphocyte‐mediated control of virus infection.
Mechanism of immune complex‐mediated damage: induction of interleukin 1 by immune complexes and synergy with interferon‐γ and tumor necrosis factor‐α
Authors: Chantry David , Winearls Chris G. , Maini Ravinder N. , Feldmann Marc 
Published: March 2007

AbstractThe ability of immune complexes derived from patients with type II mixed essential cryoglobulinemia to trigger the production of interleukin 1 (IL 1) was investigated. Immune complexes containing either IgM/IgG or IgA/IgG aggregates were shown to induce IL 1 production in human peripheral blood monocyte‐enriched populations. Interferon‐γ alone did not induce detectable IL 1, but increased the IL 1 production induced by the immune complexes. Tumor necrosis factor‐α, which is a potent inducer of IL 1, also enhanced IL 1 production following stimulation with suboptimal doses of the immune complex. The findings suggest that immune complexes may induce inflammation partly due to their capacity to induce the synthesis of IL 1.
The expression of I‐A correlates with the uptake of interferon‐γ by macrophages
Authors: Celada Antonio , Maki Richard A. 
Published: March 2007

AbstractThe current studies were designed to examine some of the requirements for I‐A expression when macrophages (MΨ) were treated with interferon‐gamma (IFN‐γ). In order to define the minimum time required for IFN‐γ to induce surface expression of I‐A antigen on bone marrow‐derived MΨ, cells were incubated with IFN‐γ for varying lengths of time, washed and thereafter incubated for 72 h before assaying I‐A surface expression. Using saturating amounts of IFN‐γ (300 IRU/ml), we found that between 0 and 30 min of IFN‐γ treatment there is a direct correlation between the length of treatment and the level of I‐A surface expression. When the steady state level of RNA for the I‐Aβ gene was assayed, a low level of I‐Aβ RNA was seen in cells treated for 10 min with saturting amounts of IFN‐γ (300 IRU/ml) while a 30‐min or 60‐min exposure of cells to the same concentration of IFN‐γ resulted in a steady increase in the level of I‐Aβ RNA. Similar results were found when we measured the levels of RNA for the tumor necrosis factor and C3 complement genes, both of which are induced by IFN‐γ in MΨ. MΨ treated with low amounts of IFN‐γ (3 IRU/ml) for 30 min do not express cell surface I‐A. Cells incubated continuously for 72 h with 3 IRU/ml of IFN‐γ expressed a level of I‐A on the surface equivalent to the level of I‐A expressed on cells treated for only 30 min with 300 IRU/ml of IFN‐γ. Based on the observed correlation between either the IFN‐γ concentration or the length of time the cells were exposed to IFN‐γ, or the level of I‐A expression on MΨ, we conclude that the expression of I‐A correlates with the uptake of IFN‐γ.
Interleukin 1 and tumor necrosis factor‐α additively increase the levels of granulocyte‐macrophage and granulocyte colony‐stimulating factor (CSF) mRNA in human fibroblasts
Authors: Seelentag Walter , Mermod Jean‐Jacques , Vassalli Pierre 
Published: March 2007

AbstractRecombinant interleukin (IL) 1 β and tumor necrosis factor/cachectin (TNF‐α) induce, usually within 2 h, a dose‐dependent increase in the levels of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) and G‐CSF mRNA in cultured human fibroblasts. Maximal induction is reached at about 4–8 h and usually last for at least 48 h. IL 1β and TNF have additive effects on the levels of GM‐ and G‐CSF mRNA, and on the secretion of G‐CSF activity into the culture medium. IL 1α has the same additive effect that IL 1β has with TNF, but no additive effect with IL 1β. In contrast, the high basic level of M‐CSF (CSF‐1) mRNA shows little or lower variations in response to IL 1, TNF‐α or both IL 1 and TNF‐α also induce, with similar kinetics, an increase in IL 1β but not mRNA level. In contrast to what is observed with macrophages and endothelial cells, E. coli lipopolysaccharide does not modify the fibroblast CSF mRNA level up to 48 h of culture.
Absence of homologous restriction factor does not affect CTL‐mediated cytolysis
Authors: Krähenbühl Olivier P. , Peter Hans H. , Tschopp JÜRg 
Published: March 2007

AbstractHomologous restriction factor (HRF) is a membrane protein of erythrocytes and leukocytes that inhibits the complement (C5b‐9)‐mediated lysis in a species‐restricting manner. HRF has also been reported to inhibit perforin‐mediated cytolysis and postulated to play a role in cytotoxic T lymphocyte (CTL) self‐protection. We show that paroxysmal nocturnal hemoglobinuria (PNH) erythrocytes, lacking HRF, are no more sensitive to Ca2+‐dependent human CTL‐mediated lysis than normal erythrocytes. Furthermore, mouse and normal human erythrocytes, as well as PNH erythrocytes, are similarly lysed by isolated murine perforin‐containing granules. We conclude that HRF does not inhibit perforin‐mediated lysis and therefore is not likely to play a role in CTL self‐protection.
Immunoregulation through CD8 (Ly‐2): state of aggregation with the α/β/CD3 T cell receptor controls interleukin 2‐dependent T cell growth
Authors: Jönsson Jan‐Ingvar , Boyce Neil W. , Eichmann Klaus 
Published: March 2007

AbstractThe activation of T lymphocytes by an antigenic challenge requires that the CD3 T cell receptor α/β (TcR) is bound to an appropriate ligand, i.e. major histocompatibility complex antigen, on an antigen‐presenting cell. In addition, numerous studies suggest that the accessory molecules CD4 and CD8 participate in the recognition process, and may have inhibitory as well as augmenting effects depending on the ways in which they participate. In the present study we attempt to define the conditions by which CD8 exerts enhancing and inhibitory effects on resting CD8 T cell activation, and which parameters of activation are regulated through participation of CD8/CD4. We find that experimental procedures leading to TcR‐CD8 aggregation induce T cell activation whereas experimental procedures preventing TcR‐CD8 aggregation inhibit T cell activation. CD8/CD4‐induced variations in the extent of T cell activation are apparent as variations in interleukin 2 (IL 2)‐dependent growth and in the number of blastoid cells bearing IL 2 receptors. Inhibition of CD8 T cell activation is successful only if the majority, if not all CD8 molecules are occupied by soluble antibody. This latter finding argues against the suggestion of other groups that CD8 may be a receptor for negative signaling. Rather, the results support the alternative notion that a basal level of TcR‐CD8 aggregation, existing in the resting state or induced by TcR‐ligand interaction, is an essential prerequisite for CD8 T cell activation. Enhancement or depression of this basal level of aggregation causes facilitation or inhibition, respectively, of activation. This may be a mechanism for the regulation of IL 2‐dependent clonal expansion of T cells in immune responses.
Two classes of CD1 genes
Authors: Calabi Franco , Jarvis John M. , Martin Luis , Milstein Cesar 
Published: March 2007

AbstractHerein, we report the DNA sequence of two human CD1 genes, R2 and R3, distinct from those encoding the CD1a, ‐b and ‐c antigens. Both genes appear to have an exon/intron structure analogous to the previously analyzed CD1 genes and to be functional on the basis of their sequence. Analysis of the variability patterns, potential intramolecular interactions and predicted secondary structure profile on an alignment of all known CD1 α chains suggest some shared structural features with major histocompatibility complex class I molecules in the α1 domains but substantial differences in the α2 domains. Sequence comparison shows that, while R2 is most related to CD1a, ‐b and ‐c, albeit to a somewhat lower degree than the latter are to themselves, R3 is more homologous to mouse than to human CD1, suggesting the existence of two functional classes within the CD1 gene family. We propose to retain the non‐committal R2 and R3 names until the putative antigens have been identified and their tissue distribution has been established.
Differential regulation of lipopolysaccharide‐induced interleukin 1 and tumor necrosis factor synthesis: effects of endogenous and exogenous glucocorticoids and the role of the pituitary‐adrenal axis
Authors: Zuckerman Steven H. , Shellhaas James , Butter Larry D. 
Published: March 2007

AbstractIntraperitoneal injection of a sublethal dose of lipopolysaccharide (LPS) into mice resulted in the appearance of tumor necrosis factor (TNF) in the serum within 45 min. Maximal serum TNF was detected by 1 h, and by 3–4 h TNF levels were no longer significantly above baseline. Injection of mice with an additional dose of LPS at 4 h resulted in no further increase in serum TNF. The in vivo kinetics of TNF appearance correlated with in vitro studies in which TNF mRNA was detected in murine peritoneal macrophages 30 min after LPS stimulation. The increase in serum TNF was not detected in mice treated with dexamethasone, 3 mg/kg, prior to LPS stimulation. The decrease in TNF correlated with the appearance of significant amounts of endogenous serum corticosterone which were maximal by 3 h. Further evidence for the role of endogenous steroids in the modulation of serum TNF levels was obtained in studies with adrenalectomized or hypophysectomized mice. Compared to sham‐operated animals, serum TNF levels remain elevated 5 h post LPS stimulation in adrenalectomized or hypohysectomized mice. In contrast with the transient increase in TNF, serum IL 1 was maximal 4 h post LPS injection and remained elevated at 24 h. In vitro studies with primary cultures of human peripheral blood monocytes and human umbilical cord vein endothelial cells demonstrated that LPS‐induced mono‐cyte IL 1 levels were reduced approximately 5‐fold by 10‐1 M dexamethasone while dexamethasone had only minimal effects on endothelial cell IL 1. Therefore, the in vitro data would suggest that the maintenance of elevated IL 1 levels coincident with the appearance of endogenous corticosteroids during LPS shock is related to the synthesis of IL 1 by both monocyte‐macrophages and non‐myeloid cell populations including endothelial cells.
Alternative molecular form of human T cell‐specific antigen CD27 expressed upon T cell activation
Authors: Borst Jannie , Sluyser Carlotte , Vries Evert De , Klein Hanneke , Melief Cornelis J. M. , Van Lier René A. W. 
Published: March 2007

AbstractThe CD27 membrane antigen is exclusively present on a large subset of human peripheral blood T lymphocytes and on mature thymocytes. Several observations point towards a specific role of this molecule on activated T cells. Upon T cell activation induced via the T cell receptor complex, CD27 expression greatly increases, while addition of anti‐CD27 monoclonal antibodies amplifies the proliferative response. Within the CD4 subset, only CD27 T cells provide helper activity for B cell differentiation. Interestingly, CD27 expression differs not only quantitatively, but also qualitatively between resting and activated T cells. On resting cells, CD27 is a disulfide‐linked homodimer with subunits of 55 kDa molecular mass. Upon activation, also a 55‐kDa monomer seems to occur, while in addition a 32‐kDa component is found. The relationship between these two proteins has been investigated. The 55‐kDa and 32‐kDa molecules do not seem to be physically associated. The two CD27 components are structurally highly homologous as determined by two‐dimensional mapping of tryptic peptides. They both express the epitopes recognized by anti‐CD27 antibodies, indicating that the 32‐kDa molecule is also T cell specific. Both 55‐kDa and 32‐kDa molecules carry N‐linked carbohydrate groups. However, they differ in other, not yet specified, post‐translational modifications, and do not arise from a common precursor simply by alternative N‐glycosylation. The 32‐kDa form may be derived by proteolytic processing from the 55‐kDa protein, but most likely not from a larger (common) precursor. Alternatively, both molecules may arise from a common gene by alternative mRNA splicing, or be derived from highly homologous genes. The dramatic change in molecular composition of CD27 suggests a newly acquired function for CD27 on activated T cells.
The improved lytic function and in vivo efficacy of monovalent monoclonal CD3 antibodies
Authors: Clark Mike , Bindon Carol , Dyer Martin , Friend Peter , Hale Geoff , Cobbold Steve , Calne Roy , Waldmann Herman 
Published: March 2007

AbstractA series of hybrid‐hybridomas were derived by the cell fusion of a CD3 antibody‐secreting hybridoma with other Ig‐producing cell lines. The Ig molecules secreted by these hybrid‐hybridomas were fractionated by ion‐exchange chromatography, and fractions containing monovalent CD3 antibodies were tested for complement‐mediated lysis of T cells. Two monovalent CD3 antibodies with mixed heavy chain isotypes were very poor in lysis but, in contrast, a monovalent antibody possessing two identical rat γ2b heavy chains but two non‐identical light chains was found to be more lytic with human complement than the parental bivalent CD3 antibody. The difference in lysis was not readily explicable in terms of a difference in complement activation at the level of C1q binding or cell‐associated C3. A highly purified batch of this lytic monovalent CD3 antibody was prepared in a form suitable for in vivo therapy. In a preliminary clinical study in one patient with a T lymphoma in leukemic phase this monovalent CD3 antibody was found to be very effective in depleting CD3 tumor cells in the peripheral blood and bone marrow. The cells in the peripheral blood were completely cleared and there was no evidence for antigenic modulation. In addition the antibody was able to reverse cell‐mediated kidney rejection in three kidney graft patients. These results suggest that monovalent antibody may be effective in vivo as well as in vitro and that a fuller clinical evaluation is justified.
Mitogenic lectins bind to the antigen receptor on human lymphocytes
Authors: Chilson Oscar P. , Kelly‐Chilson Anne E. 
Published: March 2007

AbstractThe specificity of interactions between mitogenic and non‐mitogenic lectins and disulfide‐linked cell surface receptors on human lymphocytes was explored. Lysates (Nonidet‐P40) of surface‐radioiodinated tonsil lymphocytes and T lymphoblastoid cells (HPB‐ALL) were absorbed with lectin‐agarose derivatives (or bovine serum albumin, BSA‐agarose) or immunoprecipitated with appropriate monoclonal antibodies (mAb). Lectin eluates and solubilized immunoprecipitates were analyzed by two‐dimensional (nonreduced/reduced) sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. Radiolabeled polypeptides were visualized by autoradiography. Among the various lectin‐binding polypeptides, two disulfide‐linked heterodimers (II and III) and two apparent homodimers (I and IV) are bound by pea lectin, con‐canavalin A and lentil lectin on tonsil lymphocytes; II, III and IV are bound both leukoagglutinating (L)‐ and erythroagglutinating (E)‐phytohemagglutinins from Phaseolus vulgaris (PHA). Pokeweed mitogen recognizes only II and III. These molecules are weakly bound by peanut agglutinin, soybean agglutinin, Ulex europaeus agglutinin‐I, Dolichos biflorus agglutinin, Vicia villosa agglutinin and Sophora japonica agglutinin, but are not bound by Helix pomatia agglutinin or BSA‐agarose. Heterodimer II (82–88 kDa), comprized of 50–55‐kDa and 40–43‐kDa subunits, probably represents the α/β T cell antigen receptor (TcRα/β). Heterodimer III (64–72 kDa), comprized of 41‐kDa and 37‐kDa subunits, may represent TcRγ. The homodimers, I (120–130 kDa) and IV (55–61 kDa), comprized of 55–60‐kDa and 30‐kDa polypeptides, respectively, have apparently not been previously described. Evidence that H1‐2D4, a mAb directed against the antigen receptor on HPB‐ALL cells, and E‐PHA interact with a common molecule includes: (a) immunoprecipitation of TcR with H1‐2D4 from the glycopeptide fraction specifically eluted from insolubilized lectin with N‐acetylgalactosamine; and (b) adsorption of TcR from a solubilized H1‐2D4 immunoprecipitate by E‐PHA‐agarose. Recognition of CD3 by E‐PHA is indicated by immunoprecipitation of CD3 protein by UCHT1 from the glycopeptide fraction specifically eluted from E‐PHA. The results are consistent with the view that mitogenic lectins interact with certain disulfide‐linked molecules on human lymphocytes, including the TcR α/β and perhaps TcR γ; while some nonmitogenic lectins also recognize these receptors, the interaction is of low affinity.
Triggering of the alternative pathway of human T cell activation involves members of the T 200 family of glycoproteins
Authors: Schraven Burkhart , Roux Matthias , Hutmacher Beate , Meuer Stefan C. 
Published: March 2007

AbstractThe present report describes functional characteristics of a monoclonal antibody (mAb), TA/211, which is reactive with a common determinant of the human CD45 molecules. When added to purified testing human T cells, TA/211, which is itself not mitogenic, leads to a strong proliferative response in combination with submitogenic concentrations of anti‐T112 plus anti‐T113 mAb. Interestingly, while amplifying anti‐CD2‐mediated immune responses, T cell activation induced through triggering of the CD3 molecule is not enhanced by TA/211, indicating that the triggering signal provided through CD45 is restricted to alternative pathway activation.Employing T cell subsets negatively selected for the expression of CD45R molecules defined by the mAb anti‐2H4 or UCHL1, respectively, it is demonstrated that resting T cells expressing the 2H4 molecules proliferate much stronger to TA/211 than the UCHL11 T cell subset. Together with the finding that the 2H4 T cell subset can be activated by the concomitant binding of anti‐CD2 antibodies plus anti‐2H4, these data strongly suggest that the high molecular weight species of CD45 expressed by unprimed T cells are themselves involved in T cell activation via the alternative pathway.
The conformation of the CD3 complex on T lymphocytes is modified by calcium ions
Authors: Breittmayer Jean‐Philippe , Schaffar Laurence , Bourel Dominique , Fehlmann Max 
Published: March 2007

AbstractWhile calcium ions are known to play a prominent role in signal transduction in the activation of T lymphocytes, its mechanism of action, target and function have not been elucidated. One crucial event in the calcium‐dependent process is the activation of the CD3 complex, and this, too, is not understood. While studying the release of Ca2+ from intracellular stores by several monoclonal antibodies (mAb) against CD3, we found that one of them, mAb 141, was ineffective unless free Ca2+ was present in the external medium. By flow cytometric analaysis of the binding of this mAb to Jurkat T cells and peripheral blood lymphocytes we showed that 141 does not recognize the CD3 complex when external Ca2+ is chelated by EGTA. The binding was restored by addition of Ca2+ but not Mg2+. Finally at least one subunit of the CD3 complex displayed a modified electrophoretic migration rate when immunoprecipitated by Leu‐4 in the absence of external free Ca2+. These results suggest that the conformation of the CD3 complex depends on Ca2+, the epitope recognized by 141 being concealed at low Ca2+ concentration.