bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preferential usage of JH2 in D‐J joinings with DQ52 is determined by the primary DNA sequence and is largely dependent on recombination signal sequences
Authors: Suzuki Haruhiko , Shiku Hiroshi 
Published: March 2007

AbstractRearrangement of DQ52 with JH in IgH genes takes place in a large part of lymphocytes at a very early stage of differentiation although usage of DQ52 seems to be limited in the functional IgH genes of mature B cells. A possible and likely explanation for this, is secondary D‐JH joinings occurring after the initial DQ52‐JH joinings, which becomes possible only when DQ52 segments join 5′‐located JH segments. Previously we reported the non‐random use of JH in joinings with DQ52, in which DQ52‐JH2 joinings are dominant. We questioned how the preferential usage of JH2 in DQ52‐JH joinings is determined by utilizing extrachromosomal DNA substrates.Extrachromosomal DNA substrates with a combination of DQ52 and multiple JH segments were prepared. These plasmids with a polyoma‐derived replication system were transfected into pre‐B cell lines and recombination profiles of recovered plasmids were analyzed semi‐quantitatively. Experiments with plasmids containing all four JH segments in normal configuration showed an apparent high frequency of JH2 usage, similar to the rearrangements previously observed in thymocyte genomes. In plasmids containing two JH segments, when one was JH2, it was rearranged more frequently than the other, independent of its proximity to DQ52. The JH3 with recombination signal sequences (RSS) substituted for JH2 was rearranged more frequently than the naive JH2 itself indicating the importance of RSS. A JH3 hybrid with the 200 bp upstream sequence of JH2 but excluding RSS, however, failed to increase JH3 use. The addition of one nucleotide to the 22‐bp spacer of JH1 RSS increased the frequency of JH1 usage. These observations suggest that the preferential usage of JH2 is determined by the primary DNA sequence and is largely dependent on RSS.
Heterogeneous susceptibility of human melanoma clones to monocyte cytotoxicity: Role of ICAM‐1 defined by antibody blocking and gene transfer
Authors: Jonjic Nives , Alberti Saverio , Bernasconi Sergio , Peri Giuseppe , Jilek Petr , Anichini Andrea , Parmiani Giorgio , Mantovani Alberto 
Published: March 2007

AbstractFive clones derived from the same human malignant melanoma lesion were studied for their susceptibility to killing by human monocytes activated by exposure to interferon (IFN)‐γ and lipopolysaccharide. Melanoma clones were heterogeneous in their susceptibility to human monocyte cytotoxicity, with one clone (2/21) exhibiting extremely low levels of lysis. The different levels of susceptibility to monocyte cytotoxicity were not accounted for by susceptibility or resistance to monokines [tumor necrosis factor (TNF), interleukin (IL)‐1 and IL‐6] because: (a) these effector molecules had little (TNF) or no (IL‐1 and IL‐6) cytolytic activity under these conditions; and (b) anti‐TNF antibodies had marginal effects on cytotoxicity. Monocytes bound less to resistant than to susceptible melanoma cells. Monocyte‐resistant 2/21 melanoma cells expressed substantially lower levels of ICAM‐1 and VLA‐4 than susceptible cells. Anti‐CD18 and, to a lesser extent, anti‐ICAM‐1 mAb inhibited binding and cytotoxicity of human monocytes on malignant melanoma whereas anti‐VLA‐4 had no inhibitory action. Transfection of the ICAM‐1 gene under the control of a constitutive promotor resulted in high levels of expression of ICAM‐1 in 2/21 melanoma cells and, concomitantly, in augmented susceptibility to activated monocyte cytotoxicity. The augmented killing of ICAM‐1‐transfected 2/21 cells was inhibited by anti‐ICAM‐1 mAb. These results demonstrate that the CD18‐ICAM‐1 adhesion pathway can play an important role in the expression of human monocyte cytotoxicity on melanoma target cells and that heterogeneity in expression of ICAM‐1 can underlie differences in susceptibility to tumoricidal activity.
The induction of resting B cell differentiation does not require T cell contact
Authors: Julius Michael , Haughn Lori 
Published: March 2007

AbstractA T cell clone as well as immediately ex vivo CD4+ lymph node T cells are shown to support the differentiation of co‐cultured resting B cells in the absence of T cell‐B cell contact. Antibodies specific for class II products of the major histocompatibility complex inhibit the transactiration of resting but not activated B cells. This differential inhibition pattern indicates that the responses obtained from resting B cell populations are not due to their contamination with B cell blasts. Further, supernatants prepared from an activated T cell clone induce resting B cell differentiation. Two lines of evidence suggest that the activity contained in these supernatants can be attributed to interleukin (IL)‐5. Activity is neutralized by monoclonal anti‐IL‐5; and both recombinant and affinity‐purified IL‐5 induce the differentiation of immediately ex vivo resting and activated B cells with comparable efficiency. Taken together, these results demonstrate that contact with T cells does not provide prerequisite signals for the induction of resting B cell differentiation.
Liver of MRL/lpr mice contain interleukin‐4‐producing lymphocytes and accessory cells that support the proliferation of Th2 helper T lymphocyte clones
Authors: Magilavy Daniel B. , Foys Kathleen M. , Gajewski Thomas F. 
Published: March 2007

AbstractHepatic nonparenchymal cells (NPC) from mice of nonautoimmune strains support the proliferation of only Th1 and not Th2 helper T lymphocyte (HTL) clones. Because of the multiple systemic and liver‐specific immune defects in the autoimmune MRL/lpr mouse strain, we have explored the possibility that hepatic accessory cells from MRL/lpr mice are capable of stimulating the proliferation of Th2 HTL. We report here that hepatic NPC from MRL/lpr and C3H/lpr female mice older than 8 weeks, in contrast to hepatic NPC from MRL/++ and C3H/HeN strains, are able to support in vitro the proliferation of both Th1 and Th2 CD4 clones. Additionally, hepatic lymphocytes (HL) from MRL/lpr mice can be stimulated to produce interleukin (IL)‐4 to a much higher degree than HL from the nonautoimmune strains. These results suggest that the activation of Th2 cells by hepatic NPC and production of IL‐4 by HL may contribute to the immunologic aberrations in the MRL/lpr mouse strain.
Phenotypic changes accompanying positive selection of CD4+CD8+ thymocytes
Authors: Swat Wojciech , Dessing Mark , Baron Agnes , Kisielow Pawel , von Boehmer Harald 
Published: March 2007

AbstractWe know little about the way mature CD4 (helper) and CD8 (killer) T cells develop from thymic CD4+CD8+ precursors. Here we show that small but not large CD4+CD8+ cells with high levels of the αβ T cell receptor (TcRhigh) result from positive selection. Neither CD4+CD8+ cells with low TcR levels nor large CD4+CD8+ thymocytes with high TcR levels differentiate in vitro. However, small CD4+CD8+ cells with high TcR levels develop in vitro into mature cells by gradually decreasing the surface levels of one or the other co‐receptor and acquiring the potential to respond with proliferation to ligation of the TcR. Small CD4+CD8+ cells with high levels of a major histocompatibility complex (MHC) class I‐restricted transgenic TcR develop in vitro exclusively into CD4−CD8+ cells while small CD4+CD8+ TcRhigh cells with heterogeneous TcR from various mice yield both CD4 and CD8 T cells. While these experiments are consistent with an instructive model of CD4/CD8 lineage commitment they do not rule out other mechanisms which require multiple TcR‐MHC ligand interactions in the generation of mature αβ T cells.
Characterization of nuclear protein binding to the interferon‐γ promoter in quiescent and activated human T cells
Authors: Brown David A. , Kondo Kimi L. , Wong Shen‐Wu , Diamond Don J. 
Published: March 2007

AbstractNuclear protein binding to the human interferon‐γ (IFN‐γ) promoter was investigated to determine the structural basis for the control of gene expression during T cell activation. DNase I footprinting of gel‐shift complexes demonstrated that proteins bind to two downstream (−124 to −114 and −36 to −30) and one upstream (−534 to −486) element in the IFN‐γ gene promoter. Treatment of human peripheral blood lymphocytes or continuous T cell tumors with phorbol 12‐myristate 13‐acetate (PMA) plus phytohemagglutinin or calcium ionophore results in a pattern of response that is similar when using either the upstream or downstream elements. Upon induction of T cells, the lower mobility gel‐shift band disappears. Yet the equivalent band which is also present in non‐T cells is unperturbed after PMA + calcium ionophore treatment. The higher mobility band which is modified upon induction is restricted to the T cell lineage. Upstream and downstream elements share similar protein‐binding motifs as indicated by the homology of footprinted sequences, the similarity of protein‐binding patterns, and the ability of these elements to compete against each other in gel‐shift protein‐binding assays. Protein binding to the downstream elements appears to be interactive, since both sites are required for complex formation. When either of the two downstream elements is disrupted by site‐directed mutagenesis, the higher mobility gel‐shift band is diminished by an amount that is consistent with the reduction in reporter (chloramphenicol acetyltransferase) gene expression. Therefore, proteins in the ubiquitous gel‐shift band appear to be associated with the inactive state of IFN‐γ, while the modified band is closely associated with the positive regulation of IFN‐γ gene expression.
Macrophage‐induced cytotoxicity of N‐methyl‐D‐aspartate receptor positive neurons involves excitatory amino acids rather than reactive oxygen intermediates and cytokines
Authors: Piani Daniela , Spranger Matthias , Frei Karl , Schaffner Andreas , Fontana Adriano 
Published: March 2007

AbstractThe co‐localization of activated macrophages and damaged neurons observed in brain injury and degenerative brain diseases may hint to macrophage‐induced neuronal cytotoxicity. Recently, macrophages have been found to secrete neurotoxic molecules such as radical oxygen intermediates and glutamate, the latter interacting with N‐methyl‐D‐aspartate (NMDA) receptors. As shown in the present study, brain macrophages termed microglial cells co‐cultured with differentiated cerebellar neurons excert potent neurotoxic effects. Neurotoxicity is unlikely to be due to cytokines since tumor necrosis factor (TNF)‐α, interleukin (IL)‐1β, IL‐6 and interferon (IFN)‐α/IFN‐β/IFN‐γ had no such effects. In contrast, when treating neurons with H2O2 or oxygen radical‐generating systems cytotoxicity was induced. Furthermore, microglia were found to produce O and H2O2 when triggered with phorbol 12‐myristate 13‐acetate. However, in co‐cultures of neurons and microglia, oxygen‐radical scavengers catalase and superoxide dismutase, failed to protect neurons from microglia‐induced killing. Moreover, when using undifferentiated neurons which are susceptible to H2O2 but not to NMDA receptor‐dependent killing, microglia did not destroy the neurons. Thus, the amount of reactive oxygen intermediates produced by microglia in co‐culture do not reach the critical concentrations required for neurotoxicity. As dibenzocyclohepteneimide, an antagonist to NMDA receptors neutralized neurotoxicity in microglia‐neuronal co‐cultures, excitatory amino acids released by microglia are suggested to compose the major determinant of neurotoxicity.
Netwhat?
Authors: Etlinger Howard M. , Gray David 
Published: March 2007

AbstractThe hallmark of an antibody response is considered to be its specificity for the immunogen. Nonetheless, most antibody elicited by an immunogen has been reported to be unreactive with it. We have evaluated specificity by characterizing the primary antibody response of mice to heat‐aggregated human γ‐globulin with four approaches: (a) quantification of antibody‐producing cells; (b) hybridoma analysis; (c) in situ antigen binding and (d) analysis of secreted antibody. The results show that the nonspecific component of this response is negligible. These observations suggest that such a component is not a basic feature of the antibody response and it is discussed that nonantigen‐specific antibody may arise from a variety of causes many of which are artifactual.
CD4‐class II major histocompatibility complex interaction does not enhance killing by a class I‐restricted CD4+CD8+ cytotoxic T cell clone
Authors: McAdam Alexander J. , Blieden Timothy M. , Frelinger John G. , Lord Edith M. 
Published: March 2007

AbstractAs unusual tumor‐specific cytotoxic T lymphocyte (CTL) clone was isolated which expressed both CD4 and CD8 molecules. The target cells for this CTL can be induced to express either class I major histocompatibility complex (MHC) alone (with dimethylsulfoxide) or both class I and class II MHC (with interferon‐γ). Lysis of the tumor target depends on expression of class I MHC molecules, but does not require expression of class II MHC molecules. Furthermore, the lysis of target cells expressing both class I and class II is inhibited only by antibodies to class I (Kd), and not by antibodies to class II, demonstrating that the T cell receptor is class I restricted. We have used this CTL to assess the role of the interaction between CD4 and class II MHC in the absence of a class II‐restricted T cell receptor. Our data indicate that CD4‐class II interaction does not contribute to recognition by T cells in the absence of binding of the T cell receptor to class II molecules.
Langerhans cells of the human skin possess high‐affinity 12(S)‐hydroxyeicosa tetraenoic acid receptors
Authors: Arenberger Petr , Kemény Lajos , Rupec Rudolf , Bieber Thomas , Ruzicka Thomas 
Published: March 2007

AbstractThe arachidonic acid metabolite 12‐hydroxyeicosatetraenoic acid (12‐HETE) is the main eicosanoid formed by epidermal cells and is assumed to play an important role in skin physiology and pathophysiology. Our aim was to find out whether epidermal Langerhans cells possess specific receptors for 12‐HETE which would mediate the effects of this eicosanoid in their skin microenvironment. By radioligand binding studies on isolated human Langerhans cells, we could identify specific binding sites for 12(S)‐HETE. The analysis of binding data revealed a single class of binding sites with a Kd of 3.32 ± 0.45 nM and a Bmax of 691 000 ± 58 000 receptors per cell. The binding was saturable, readily reversible, and specific for 12(S)‐HETE. The receptor is likely to mediate the potent chemotactic response of human Langerhans cells towards 12(S)‐HETE, which we previously described. Our results strongly suggest that extremely low concentrations of 12‐HETE which is formed by epidermal keratinocytes may dramatically influence the biology of Langerhans cells by receptor‐mediated effects.
Improved survival from potentially lethal graft‐vs.‐host disease by donor pretreatment with a recipient‐specific blood transfusion. I. Requirements for induction and specificity of the effect
Authors: Knulst André C. , Bril‐Bazuin Clara , Tibbe G. John M. , Benner Robbert 
Published: March 2007

AbstractPretreatment of prospective donors of hemopoietic cells with a single recipientspecific blood transfusion can significantly decrease the morbidity and mortality of graft‐vs.‐host disease (GVHD) in lethally irradiated, allogeneically reconstituted mice. This beneficial effect of donor pretreatment could be demonstrated in donor‐recipient strain combinations that were H‐2 + non‐H‐2, H‐2, or only class II‐disparate, but not in the class I‐disparate C57BL‐B6.C‐H‐2bm1 strain combination. The effect was proportional to the amount of recipient‐strain blood used for transfusion. Donor transfusion with a single dose of 1 ml recipient‐specific whole blood resulted in minimum GVHD, lower doses being less or not effective. The interval between donor pretreatment and the use of their hemopoietic cells for reconstitution appeared to be important. The best survival was found at an interval of 4 days. Multiple transfusion was not more effective than a single one. We compared the effectiveness of whole blood and irradiated spleen cells for donor pretreatment. Both protocols have been shown previously to suppress anti‐recipient delayed‐type hypersensitivity. It appeared that the blood transfusion protocol was superior to the spleen cell protocol. The beneficial effect appeared to be recipient specific, since a third‐party blood transfusion did not improve GVHD. We found that the beneficial effect of donor blood transfusion was due to suppression of the anti‐host immune response. The donor blood transfusion was able to induce bystander suppression to alloantigens that were not used for the induction of suppression, provided they were co‐expressed with the specific alloantigens by the recipients. This also indicates that, although the induction of suppression is specific, the ultimate suppressive effect is nonspecific.
Effects of the thymic microenvironment on the response of thymocytes to stimulation
Authors: Moore Nel C. , Jenkinson Eric J. , Owen John J. T. 
Published: March 2007

AbstractWe show that, in vitro, the response of thymocytes to certain stimuli, and their survival largely depend on the nature of the culture environment, i.e. whether thymocytes are stimulated within intact thymus lobes or in cell suspension. Exposure of isolated thymocytes to 12‐O‐tetra‐decanoylphorbol 13‐acetate (TPA) + ionomycin rapidly abolishes the expression of recombination‐activating gene‐1 (RAG‐1) mRNA (3 h), down‐regulates CD4 surface antigen expression (3 h), and enhances apoptosis (24 h). On the other hand, when thymocytes are cultured in intact lobes, TPA plus ionomycin down‐regulate rather than abolish RAG‐1 mRNA expression (3 h), have little effect on CD4 expression even following 24‐h exposure, and only marginally induce apoptosis (24 h). Differences between the culture systems are less pronounced in reponse to anti‐CD3 antibodies. Therefore, it appears that removing thymocytes from their thymic microenvironment makes the cells more susceptible to certain stimuli, possibly by altering their physiological status. In addition, it has been suggested that termination of RAG‐1 expression can be linked to thymocyte selection processes. We found that the down‐regulation of RAG‐1 expression was not dependent on the induction of apoptosis, supporting a proposed link with positive selection.
Genetics of nonspecific immunity: I. Bidirectional selective breeding of lines of mice endowed with maximal or minimal inflammatory responsiveness
Authors: Ibanez Olga M. , Stiffel Claude , Ribeiro Orlando G. , Cabrera Wafa K. , Massa Solange , De Franco Marcelo , Sant'Anna Osvaldo A. , Decreusefond Claude , Mouton Denise , Siqueira Maria , Biozzi Guido 
Published: March 2007

AbstractThe genetic regulation of acute inflammatory reaction (AIR) was studied by the method of bidirectional selective breeding, used to produce a line of mice giving the maximal and a line of mice giving the minimal inflammatory reaction (AIR max and AIR min, respectively). The AIR was triggered by subcutaneous injection of a neutral substrate (suspension of polyacrylamide microbeads), and measured by the leukocyte and serum protein accumulation in the exudate. The two parameters are positively correlated and present a normal frequency distribution. The highly genetically heterogeneous foundation population was produced by the equipoised intercrossing of eight inbred strains of mice, and selective breeding carried out by assortative matings of extreme phenotypes. The response to selection in 11 consecutive generations was highly asymmetrical: a marked AIR increase in the AIR max and no change in the AIR min line occurred. The mean value of realized heritability in the AIR max line was 0.26 and 0.18 for cell and protein concentrations, respectively. The response to selection must have resulted from the interaction of seven to nine independent gene loci endowed with additive effects. The lack of response to selection of the AIR min line is discussed. The large inter‐line difference opens new possibilities for studying the biochemistry and molecular genetics of inflammation, and also for investigating the beneficial or detrimental effect of inflammatory responses.
Evidence for oligoclonality of T cell receptor δ chain transcripts expressed in rheumatoid arthritis patients
Authors: Olive Colleen , Gatenby Paul A. , Serjeantson Susan W. 
Published: March 2007

AbstractThe inflamed synovium of rheumatoid arthritis (RA) patients contains γ/δ T cells which express predominantly T cell receptor (TcR) variable (Vδ1 and Vδ2 chains. Such T cells may contribute to the pathogenesis of RA. To assess the extent of clonality among these T cell populations we sequenced the junctional regions of rearranged TcR Vδ1‐Cδ and Vδ2‐Cδ chain cDNA, after using the polymerase chain reaction (PCR) to amplify TcR δ chain transcripts isolated from synovial membrane mononuclear cells (SMC) of five RA patients. The sequences of these δ chain transcripts were compared with those found in peripheral blood mononuclear cells (PBMC) of the same patients and in PBMC of four healthy controls. In contrast to control PBMC, Vδ1 chain cDNA derived from PBMC of three patients showed a strong bias towards usage of the same V‐joining (J) combination and junctional region sequences, although the specific sequences were unique in each patient. However, oligoclonality of the Vδ1 chain was less marked in SMC of two of these patients and absent in SMC of the other patients. For Vδ2, oligoclonality was detected in PBMC of two patients. In SMC of a single patient, a dominant Vδ2 transcript was detected that utilized the Jδ2 segment, which was rarely expressed in the normal TcR repertoire. These results indicate in vivo clonal expansion of Vδ1 and Vδ2‐expressing γ/δ T cells in the peripheral blood of RA patients and a synovial T cell infiltrate which consists largely of polyclonally expanded γ/δ T cells, but shows clonal dominance in some patients. Our data strongly support a role for Vδ1+ and Vδ2+ γ/β T cells in the pathogenesis of RA, and, although the nature of the antigen(s) recognized by these cells remains elusive, this report suggests the potential involvement of antigen(s) specific for the V region and V‐J junction.