bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isolation and characterization of a cDNA encoding a putative cytokine which is induced by stimulation via the CD2 structure on human T lymphocytes
Authors: Chang Hsiu‐Ching , Reinherz Ellis L. 
Published: March 2007

AbstractTo define activation‐specific sequences in human T lymphocytes, a cDNA library was constructed by subtractive hybridization using resting and stimulated peripheral blood lymphocyte pairs. Stimulation of peripheral blood lymphocytes was achieved by triggering with mitogenic anti‐CD2 (T11) monoclonal antibodies. Differential library screening with cDNA probes derived from stimulated vs. resting peripheral blood lymphocytes led to identification of a novel sequence, termed HC21. The predicted primary and secondary structure of HC21 deduced from the translated nucleotide sequence suggest that the gene encodes a secreted protein of 92 amino acids including a 23‐residue leader sequence. Northern blot analysis demonstrates that HC21 mRNA is induced in peripheral blood T lymphocytes and interleukin 2‐dependent T cell clones within 10 min following stimulation via CD2, while steady‐state RNA expression is maximal by 2 h. Although the kinetics of HC21 expression are similar after stimulation via the antigen/major histocompatibility complex receptor (CD3‐Ti), CD3‐Ti triggering leads to less accumulation of HC21 RNA than CD2 triggering. In contrast, recombinant interleukin 2 does not induce detectable HC21 RNA expression in T cell clones. Transient expression of the HC21 cDNA in COS cells results in a readily detectable protein band in sodium dodecyl sulfate‐polyacrylamide gel electrophoresis analysis of radiolabeled cell supernatants consistent with HC21 encoding a secreted product. Protein sequence analysis reveals a striking homology (up to 76% identity at amino acid level) with other members of a recently described lymphokine family whose functions are yet to be defined.
Reticulum cell sarcomas of SJL mice have rearranged immunoglobulin heavy and light chain genes
Authors: Stavnezer Janet , Lasky Jennifer L. , Ponzio Nicholas M. , Scheid Margrit P. , Jeanette Thorbecke G. 
Published: March 2007

AbstractThe immunoglobulin (Ig) heavy (H) and light (L) chain gene rearrangements of the high incidence SJL lymphomas (reticulum cell sarcoma, RCS) have been analyzed. Both primary and transplanted RCS show rearrangements of H and χ L chains, demonstrating that these tumors are of B cell origin. These data are consistent with previous results indicating that these tumors are a mouse model for follicular lymphoma. A long‐term transplanted line and the in vitro line derived from it, cRCS‐X, have a single rearranged JH−Cγ2a fragment and one rearranged Cα gene fragment which does not hybridize with a probe for the JH gene segments. These cell lines also have two rearranged Jχ−Cχ fragments. Primary tumors and early passages are more heterogeneous with respect to Ig gene rearrangements, possibly because more than one B cell clone is present.Although no synthesis of IgG2a, or of any Ig, could be detected by the in vitro cRCS‐X cells, these cells contain abundant poly(A)+ RNA that hybridize with γ2a and χ probes as well as lesser amounts of α and ε RNA. None of these H chain RNA hybridized with probes for the JH gene segments. The ε and α RNA are the same size as transcripts of germ‐line CH genes which have been identified in other systems. However, the γ2a RNA are smaller than previously described germ‐line Cγ2a RNA and appear to be transcribed from aberrantly rearranged JH−Cγ2a genes.
Inhibition of T cell response with peptides is influenced by both peptide‐binding specificity of major histocompatibility complex molecules and susceptibility of T cells to blocking
Authors: Lehmann Paul V. , Cardinaux Francis , Appella Ettore , Muller Simone , Falcioni Fiorenza , Adorini Luciano , Nagy Zoltan A. 
Published: March 2007

AbstractSynthetic peptides corresponding to sequences 46–62 and 51–62 of mouse lysozyme and 46–61 of hen egg‐white lysozyme (HEL) were used as competitors in a variety of T cell responses. The competitors, according to their binding specificity for major histocompatibility complex (MHC) were expected to inhibit T cell responses restricted to I‐Ak, but not those restricted to I‐Ad, I‐Ek molecules. In competition experiments with T cell hybridomas, the poor binder I‐Ed molecule required 10‐ to 15‐fold higher competitor concentrations than the good binder I‐Ak molecule to achieve 50% inhibition of antigen presentation. Similarly, the nonresponder state of H‐2d mice to HEL peptide 46–61 could be overcome by increasing the immunizing dose, and proliferative T cell responses to different antigens in association with a variety of class II MHC molecules could be blocked by the mouse lysozyme and HEL peptides. Thus, the capability of some and failure of other MHC molecules to bind certain peptides appeared quantitative, rather than of an all or none nature, in these experimental systems. The susceptibility of uncloned T cell lines to peptide competitors was found to decrease with time. Lines maintained by repeated restimulation with antigen and APC, but without exogeneous interleukin 2, acquired resistance within weeks. In contrast, T cell clones retained their susceptibility to peptide competitors over a long period of time. The latter data raise the possibility that a competition between ubiquitous (self) peptides and foreign antigen may result in the selection of T cells that have high avidity for the activating antigen‐MHC complex, and are thus relatively resistant to competition at the level of antigen presentation.
Interferon‐γ activates multiple pathways to regulate the expression of the genes for major histocompatibility class II I‐Aβ, tumor necrosis factor and complement component C3 in mouse macrophages
Authors: Celada Antonio , Klemsz Michael J. , Maki Richard A. 
Published: March 2007

AbstractThe purpose of this study was to obtain additional information on the mechanism by which interferon‐γ (IFN‐γ) is able to regulate gene expression in macrophages. The expression of the genes for class II histocompatibility I‐Aβ, tumor necrosis factor (TNF) and complement component C3 was assayed after treating bone marrow macrophages with IFN‐γ. Each gene displayed a characteristic pattern of regulation. First, the increase in the level of RNA for each gene followed different kinetics. The level of TNF RNA increased within 15 min after IFN‐γ treatment and reached a plateau after 4 h. In contrast, there was a lag of about 4 h before the level of I‐Aβ RNA began to rise and a plateau was not reached until 48 h after the IFN‐γ treatment began. C3 gene expression followed an intermediate time course between that for TNF and I‐Aβ. Second, the expression of I‐Aβ was inhibited when cells were treated with both IFN‐γ and cycloheximide, while the expression of TNF and C3 was not. Interestingly, the sensitivity to cycloheximide only lasted 30 min following the addition of IFN‐γ, after which cycloheximide had no effect on the expression of I‐Aβ. Third, lipopolysaccharide abolished the IFN‐γ‐induced expression of I‐Aβ, but enhanced the expression of TNF. Based on these observations, we conclude that IFN‐γ must activate multiple pathways to regulate gene expression in macrophages.
Increased cyclic AMP levels block interleukin 2‐induced protein kinase C substrate phosphorylation but not the mitogenic response
Authors: Friedrich Bengt , Cantrel Doreen A. , Gullberg Martin 
Published: March 2007

AbstractProtein kinase C (PKC) has been implicated in the signaling of a number of cellular responses including activation of T cells. In the present report we have evaluated the effect of increased cAMP levels on PKC activation after stimulation of two distinct receptor systems on normal human T cells. PKC substrate phosphorylation can be induced via either the CD3 complex or, to a limited extent, the high affinity interleukin 2 (IL2) receptor. Substrate phosphorylation via both pathways is shown to be blocked by increased intracellular levels of cAMP. In accordance with previous reports, the CD3‐dependent autocrine proliferative response could also be blocked by a cAMP‐dependent mechanism. Since direct activation of PKC with a phorbol ester reversed this inhibition, a causal relationship between cAMP‐dependent PKC blockage and inhibition of the CD3 response is suggested. In contrast, however, initiation of IL2‐induced proliferation was essentially unaltered by cAMP and could progress in the apparent absence of PKC activity. Thus, this study indicates that IL2‐induced proliferation can under such conditions be completely uncoupled from IL2‐induced PKC activation in normal T cells.
Membrane IgM cross‐linking is not coupled to protein kinase C translocation in WEHI‐231 B lymphoma cells
Authors: Sarthou Pierre , Henry‐Toulmé Nelly , Cazenave Pierre‐André 
Published: March 2007

AbstractThe early molecular events involved in the process of signal transduction via membrane immunoglobulins (mIg) include phosphatidyl inositol metabolism, intracellular Ca2+ mobilization, and protein kinase C (PKC) activation. Anti‐mIg antibodies exert either stimulating or inhibitory effects depending on the activation state and/or the differentiation stage of B cells. WEHI‐231 is a murine B lymphoma that becomes inactivated upon anti‐mIg treatment. This lymphoma has an immature B cell phenotype and is considered as a model for tolerance induction in B lymphocytes. In this study, we have investigated the relationship between mIg triggering, Ca2+ elevation, PKC translocation, and growth inhibition in WEHI‐231 cells. Monoclonal antibodies to μ and χ chains of the mIgM receptor promoted a rapid increase in intracytoplasmic Ca2+ and were potent inhibitors of cell growth. Ca2+ elevation and PKC translocation have been previously shown to be associated in B lymphocytes. To study the subcellular distribution of PKC in WEHI‐231 cells, we used enzymatic assays and immunodetection methods. Although phorbol 12‐myristate 13‐acetate induced a rapid and almost complete redistribution of cytosolic PKC to the membrane fraction, anti‐mIg treatment failed to modify the compartmentalization of PKC. These findings extend recent observations suggesting that B cell triggering through mIg receptors may involve additional pathways independent from PKC activation. PKC activation in normal B cells is also believed to provide a regulatory signal which limits the magnitude of the early signals produced by anti‐mIg. Such a regulatory control is unlikely in WEHI‐231 cells, due to the dissociation between Ca2+ mobilization and PKC translocation. Our findings therefore suggest that the sensitivity of immature B cells such as WEHI‐231 to the inhibitory effects of anti‐mIg antibodies may result in part from alterations of the phosphoinositide signal transduction pathway.
Coordinated Vγ and Vδ gene segment rearrangements in human T cell receptor γ/δ+ lymphocytes
Authors: Sturm Els , Braakman Eric , Bontrop Ronald E. , Chuchana Paul , Van Griend René J. De , Koning Frits , Lefranc Marie‐Paule , Bolhuis Reinder L. H. 
Published: March 2007

AbstractMonoclonal antibodies (mAb) were used to characterize a panel (n = 46) of T cell receptor (TcR) γ/δ+ T cell clones. Three of these antibodies have been described to react with specific variable region‐encoded protein products and can therefore be used to detect functional gene rearrangements. The majority of peripheral blood‐derived clones (43 out of 45) expressed the epitopes recognized by mAb BB3, encoded by the Vδ2 gene segment and mAb TiγA, encoded by the Vγ9 gene segment. These clones lacked the antigenic determinant recognized by mAb δ‐TCS‐1, encoded by the Vδ1 gene segment. The other two peripheral blood‐derived clones and an ascites‐derived clone were TiγA‐, BB3‐ and δ‐TCS‐1+. Biochemical analysis revealed that all TiγA+, BB3+ T cell clones expressed the disulfide‐linked form of the receptor. The two peripheral blood‐derived δ‐TCS‐1+ T cell clones expressed the nondisulfide‐linked form whereas the ascites‐derived δ‐TCS‐1+ clone, AK119 expressed the disulfide‐linked form of the TcRγ/δ heterodimer. This indicates that Vδ1‐encoded δ chains can be associated either with a Cγ1‐ or a Cγ2‐encoded γ chain. The preferential use of certain Vγ and Vδ gene segments suggests the existence of a limited combinatorial diversity in TcRγ/δ heterodimers, i.e. TiγA+ (Vγ9), BB3+ (Vδ2) and δ‐TCS‐1‐ disulfide‐linked heterodimers and TiγA‐, BB3‐ and δ‐TCS‐1+ (Vδ1) disulfide‐ or non disulfide‐linked forms.
Specificity of human T lymphocytes expressing a γ/δ T cell antigen receptor. Recognition of a polymorphic determinant of HLA class I molecules by a γ/δ clone
Authors: Ciccone Ermanno , Viale Oriane , Pende Daniela , Malnati Mauro , Ferrara Giovan Battista , Barocci Sergio , Moretta Alessandro , Moretta Lorenzo 
Published: March 2007

AbstractAlloreactive clones expressing T cell receptor (TcR) γ/δ were derived by limiting dilution from CD3+CD4‐CD8‐WT31‐ populations stimulated in allogeneic mixed lymphocyte culture. These clones specifically lysed phytohemagglutinin‐induced blast cells bearing the stimulating alloantigens, whereas they had no effect on autologous or allogeneic unrelated target cells. Analysis of the reactivity with monoclonal antibodies (mAb) specific for two different subsets of TcR γ/δ (BB3 and δ‐TCS‐1) showed that five out of nine clones were BB3+, whereas the remaining reacted with δ‐TCS‐1. Therefore, we can conclude that both subsets of TcR γ/δ+ cells are able to specifically recognize and lyse allogeneic cells. mAb directed against the CD3‐TcR γ/δ molecular complex strongly inhibited the specific cytolytic activity of TcR γ/δ+ clones, whereas they had no effect on the lysis of the natural killer‐sensitive K‐562 target cells mediated by the same clones. An alloreactive δ‐TCS‐1+ clone (LM12) was further characterized for its specificity. LM12 clone had been derived after stimulation in mixed lymphocyte culture against donor M. M. (HLA typing: Aw68, 24; B35, w55; DR1, 7). The analysis of a large panel of phytohemagglutinin‐induced target cells revealed that only the HLA‐A24+ target cells were lysed. The direct evidence that the A24 molecule represented the restriction element was provided by experiments using A24‐transfected murine P815 target cells. Thus, clone LM12 efficiently lysed A24‐transfected P815 cells, but not the same cells untransfected or transfected with the Cw3 gene. Therefore, it appears that polymorphic determinants of class I major histocompatibility complex molecules can be the target of TcR γ/δ+ alloreactive cell recognition.
Mechanism of recovery from acute virus infection. VIII. Treatment of lymphocytic choriomeningitis virus‐infected mice with anti‐interferon‐γ monoclonal antibody blocks generation of virus‐specific cytotoxic T lymphocytes and virus elimination
Authors: Wille Andreas , Gessner André , Lother Heinz , Lehmann‐Grube Fritz 
Published: March 2007

AbstractIn acutely infected mice the lymphocytic choriomeningitis (LCM) virus multiplies to high titers in essentially all tissues. Around day 6, virus clearance sets in, which has previously been shown to be mediated by CD8+ cytotoxic T lymphocytes (CTL), probably by releasing (or inducing other cells to release) anti‐viral cytokines. To ascertain whether interferon‐γ plays a role, infected mice were injected once i.v. with monoclonal antibody known to neutralize this lymphokine, and the effect this had on both termination of the infection and development of LCM virus‐specific CTL was determined. Administration 1 day after infection blocked virus elimination from spleen and liver and decreased the generation of CTL; also, limiting dilution analysis revealed absence of activation of CTL precursors. In contrast, when the antibody was given 3 days after or 1 day before the virus, neither clearance nor generation of CTL was measurably affected. Furthermore, the antiviral effect of immune spleen cells after their transfer into infected recipients was not altered by treatment of the latter with monoclonal antibody. We conclude that in the generation of LCM virus‐specific CTL an early event is dependent on constitutively produced interferon‐γ; when its activity is blocked, CTL do not mature, resulting in the mouse's inability to terminate the infection.
Biased immunoglobulin variable region gene expression by Ly‐1 B cells due to clonal selection
Authors: Pennell Christopher A. , Mercolino Thomas J. , Grdina Therese A. , Arnold Larry W. , Haughton Geoffrey , Clarke Stephen H. 
Published: March 2007

AbstractMost, if not all, autoantibodies specific for bromelain‐treated mouse erythrocytes recognize the common membrane phospholipid, phosphatidyl choline (PtC). Anti‐PtC antibodies are produced by 5%‐15% of CD5+ Ly‐1 B cells of normal unimmunized mice, but not by detectable numbers of conventional CD5– B cells. At 1 week of age PtC‐specific B cells are undetectable but then increase dramatically over the next 3 to 4 weeks to reach adult numbers. We report here that PtC‐specific Ly‐1 B cells in B10.H‐2aH‐4bp/Wts mice predominantly express either of two heavy and χ chain variable (V) region gene combinations. In addition, the sequence and length of DH genes are conserved among cells expressing the same V gene combination, and the Vχ‐Jχ junctions of one group involve unusual splice sites. Preferential V gene rearrangement models are insufficient to explain the DH and Vχ‐Jχ junctional sequences or the delayed appearance of this specificity, and so they cannot solely account for the high frequency of PtC‐specific cells. These characteristics are more consistent with antigen selection. We therefore attribute the frequent use of the two V region gene combinations to selection for cells that express them and conclude that the expressed V gene repertoire of Ly‐1 B cells in adult mice is influenced by antigen selection. Apparently, there is no selection for mutant anti‐PtC antibodies of higher affinity during the formation of the Ly‐1 B repertoire because the V region genes expressed by PtC‐specific cells are unmutated. Our findings are consistent with an important, germ line‐encoded function for the immunoglobulin products of these gene combinations.
Interleukin 4 induces synthesis of IgE and IgG4 in human B cells
Authors: Lundgren Mats , Persson Ulla , Larsson Per , Magnusson Carl , Smith C. I. Edvard , Hammarström Lennart , Severinson Eva 
Published: March 2007

AbstractInterleukin (IL) 4 has been shown to regulate the IgG subclasses and induce IgE production in splenic mouse B cells. Here we show that IL 4 and phorbol 12‐myristate 13‐acetate (PMA) induce, on a per cell basis, very high IgE secretion in purified human B cells by using a mouse thymoma (EL4) co‐culture method. In addition, a marked increase in the number of IgG4‐producing cells was also observed. Furthermore, IL 2 could synergize with IL4 and PMA in the production of IgE. By using limiting dilution analysis, a considerable increase in the precursor frequency for IgE was found when IL 4 and PMA were added to cultures as compared to cultures with PMA only. This indicates that IL4 induces an isotype switch in human B cells.
The intermediate‐affinity interleukin (IL) 2 receptor expressed on Theileria annulata‐infected cells comprises a single IL 2‐binding protein. Partial characterization of bovine IL 2 receptors
Authors: Herrmann Thomas , Ahmed Jabbar S. , Diamantstein Tibor 
Published: March 2007

AbstractBovine high‐, intermediate‐ and low‐affinity interleukin 2 receptors (IL2R) were studied by ligand binding and affinity labeling using 125I‐labeled IL 2 and homobifunctional chemical cross‐linking reagents. High‐ (Kd = 17 pM) and low‐affinity (Kd > 6 nM) IL2R were detected on concanavalin A‐activated peripheral blood lymphocytes (PBL). Theileria annulata (TA)‐infected autonomously growing PBL (TA‐PBL) express predominantly intermediate‐affinity IL2R (Kd = 1 nM). Affinity‐labeling studies revealed that the high‐affinity IL2R comprises a 55‐kDa (L chain) and an additional 90‐kDa IL 2‐binding protein (H chain). TA‐PBL express predominantly the H chain. In contrast to the human chain, the bovine form was not separable by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis/urea into the two distinct bands H1 and H2 and ran in parallel to the human H2 band. These results suggest (a) that the bovine intermediate‐affinity IL 2R comprises a single H chain and (b) that the single H chain and the L chain are sufficient to form the functional high‐affinity bovine IL2R.
Alloantigen pretreatment induces a down‐regulation of the in vivo subsequent development of cytotoxic T lymphocytes directed against linked alloantigens
Authors: Schutze Marie‐Paule , Langlade‐Demoyen Pierre , Przewlocki Grzegorz , Leclerc Claude 
Published: March 2007

AbstractIn the present study, we describe a new regulatory system that influences the in vivo development of cytotoxic T lymphocytes (CTL) and that could be related to epitopic suppression. Epitopic suppression has been previously shown to occur when carrier‐primed mice are subsequently immunized with a “new” epitope coupled to the priming carrier. The suppression specifically inhibited the antibody response to the “new” epitope without affecting the secondary antibody response to the carrier.In this report, using a carrier/hapten‐carrier type of immunization protocol, we have demonstrated that a similar regulatory system could also affect the induction of CTL directed against allogeneic cells. Priming mice with an alloantigen 1 (carrier) inhibits the induction of alloantigen 2 (hapten)‐specific cytotoxic responses when the alloantigen 2 is presented in association with the alloantigen 1 on an F1 stimulator cell (hapten‐carrier conjugate). This has been demonstrated by the specific decrease of anti‐H‐2b or anti‐H‐2d CTL responses generated in C3H/He mice (H‐2k) previously primed with, respectively, H‐2d or H‐2b spleen cells before immunization with F1 (H‐2d x b) spleen cells. This suppression of the CTL responses against the second immunizing alloantigen is associated with a strong CTL response against the first priming alloantigen. The induction of the suppression is dependent on the dose of H‐2d spleen cells administered before immunization with F1 spleen cells and is not related to antigen elimination since a strong suppression of the CTL response against H‐2b antigens is shown following immunization with a mixture of F1 cells and H‐2b‐bearing cells of H‐2d‐primed animals.
Class switch from μ to δ is mediated by homologous recombination between σμ and σμ sequences in human immunoglobulin gene loci
Authors: Yasui Hisashi , Akahori Yasushi , Hirano Masami , Yamada Kazumasa , Kurosawa Yoshikazu 
Published: March 2007

AbstractClass switch of immunoglobulin from μ to γ occurs by recombination between two repetitive switch sequences: Sμ and Sγ. However, there are no such sequences in the μ‐δ introns of human and mouse genomes. Although the frequency of IgD‐secreting cells is extremely low in mouse about 1% of patients with myeloma produce IgD in human. In a previous report (Nucleic Acids Res. 1988. 16: 9497) we reported that a 442‐bp DNA sequence located in the JH‐μ intron (defined as σμ) was inserted into the μ‐δ intron (defined as σμ) in the human genome. There is no such insertion in mouse. We analyzed Ig H chain gene loci of two human IgD myelomas: one was analyzed by cloning and sequencing and the other by Southern hybridization. We found that recombination had occurred between these two homologous DNA sequences, resulting in loss of the DNA segment from σμ to σμ On the other hand, in a Burkitt lymphoma, Daudi, the DNA fragment from σμ to σμ was duplicated. These results suggest that homologous recombination between σμ and σμ sequences mediates class switch from μ to δ in human and that it occurs via unequal crossing‐over between sister chromatids or daughter chromosomes.