bluuebunny/crossref_metadata_2025_split huggingface dataset:
CD9 antigen is an accessory subunit of the VLA integrin complexes
Authors: Rubinstein Eric , le Naour François , Billard Martine , Prenant Michel , Boucheix Claude 
Published: March 2007

AbstractThe CD9 antigen is a cell surface glycoprotein of unknown function which belongs to the tetraspans family. We demonstrate here, by precipitation, Western blotting and co‐capping experiments, that this molecule is associated with a large fraction of β1 integrins in two cell lines, the pre‐B cell line NALM‐6 and the megakaryocytic cell line HEL. In HEL cells, CD9 antigen is only associated with VLA‐4. In contrast, in NALM‐6 cells, CD9 antigen is associated with both VLA‐4 and VLA‐5. On the other hand, only the β1 chain is co‐precipitated with the CD9 antigen in transfected L cells. These data show that the CD9 antigen is associated with the β1 chain rather than with a particular integrin. CD9 monoclonal antibodies (mAb) did not modify the binding of HEL and NALM‐6 cells to fibronectin, laminin or collagen. The association of CD9 antigen to VLA integrins is strengthened by the fact that both CD9 and anti‐VLA mAb induce aggregation of the two cell lines and inhibit their migration in Transwell chambers. Because the aggregating effect, but not the inhibition of migration, is observed in CEM or CD9‐transfected CEM cells, these two effects are likely to be mediated by different mechanisms.
B7/BB‐1 antigen expression on adult human microglia studied in vitro and in situ
Authors: Williams Kenneth , Ulvestad Elling , Antel Jack P. 
Published: March 2007

AbstractIn this study, we have examined the expression and function of B7/BB‐1 on individual glial cells, by utilizing surgically resected adult human central nervous system (CNS) tissues, tissues derived from fetal human CNS, and pathology material from cases of multiple sclerosis (MS). Immunofluorescence analysis using enriched adult human derived cultures of microglia and oligodendrocytes, and mixed microglia/astrocyte cultures, demonstrated that B7/BB‐1 was expressed on microglia. Adult human‐derived oligodendrocytes and astrocytes, and human fetal astrocytes were B7/BB‐1 negative under all culture conditions. Flow cytometry studies demonstrated a low basal level of B7/BB‐1 expression on microglia that was up‐regulated following incubation with interferon‐γ (IFN‐γ). Co‐culture of purified fresh allogeneic CD4+ T cells with microglia for 24 h resulted in clustering of T cells around microglia and microglial B7/BB‐1 expression. Preincubation of microglia with an anti BB‐1 monoclonal antibody (mAb) prior to microglia: CD4+ T cell co‐cultures resulted in partial inhibition of the ability of microglia both to present recall antigen to autologous CD4+ T cells and to present antigen to allogeneic CD4+ T cells in primary mixed lymphocyte reaction (1°MLR). The CTLA‐4 Ig fusion protein inhibited the ability of microglia to present antigen in both antigen presentation assays to an even greater extent than did the anti BB‐1 mAb. The BB‐1 antibody also inhibited the ability of microglia to stimulate previously activated T cells in a secondary 2° MLR. In sections of multiple sclerosis brain, B7/BB‐1 expression was observed on activated microglia in select parenchymal lesions, and on perivascular cells and infiltrating monocytes. B7/BB‐1 immunoreactivity was not found in normal appearing white matter from MS brain or from non‐inflammatory brain specimens. Our results indicate that the B7/BB‐1 molecule plays a functional role in the capacity of microglia to serve as CNS antigen‐presenting cells that can both initiate and perpetuate CD4+ T cell activation.
Structure of the human APO‐1 gene
Authors: Behrmann Iris , Walczak Henning , Krammer Peter H. 
Published: March 2007

AbstractAPO‐1/Fas (CD95) is a type 1 transmembrane protein that belongs to the tumor necrosis factor/nerve growth factor receptor family characterized by cysteine‐rich extracellular domains. Cross‐linking of APO‐1 mediates apoptosis in a variety of cells. In the present study we report the isolation and characterization of the human APO‐1 gene spanning approximately 25 kb of human chromosome 10. The gene consists of nine exons (25 bp to > 1.44 kb) separated by eight introns (152 bp to ∼ 12 kb). The boundaries of exon 2 to 5 encoding the extracellular region do not match the boundaries of the three APO‐1 protein subdomains. Exon structure and functional protein domains correspond for exon 6 encoding the transmembrane region and for exon 9 encoding the „death domain”︁. By a polymerase chain reaction‐based approach we localized major transcriptional start sites in human spleen cells 77 and 73 nucleotides upstream of the translation initiation codon of the human APO‐1 gene. Minor initiation sites were found at positions −128, −111, −91, and −74. The 5′ flanking sequence of the human APO‐1 gene is GC rich, contains a high number of CpG dinucleotides and lacks a consensus TATA box. Consensus binding sites for the transcription factors Sp1, AP‐1, AP‐2, GAF, NF‐χB, and NF‐AT were found. The elucidation of the human APO‐1 gene structure will facilitate the study of its involvement in various diseases such as in autoimmunity.
The APO‐1/Fas (CD95) receptor is expressed in homozygous MRL/lpr mice
Authors: Mariani Sara M. , Matiba Bernd , Armandola Elena A. , Krammer Peter H. 
Published: March 2007

AbstractAPO‐1/Fas (CD95) is a transmembrane receptor that transduces apoptotic signals within various cells including T and B cells. The APO‐1 gene was found to be defective in lpr mice. In these mice insertion of a retrotransposon gives rise to transcription of an abnormal mRNA and only a fraction of wild‐type APO‐1 mRNA. It is not clear if lpr mice still express wild‐type APO‐1 protein. To address this question, we prepared rabbit anti‐APO‐1 antibodies (Ab) with a peptide representing the extracellular sequence corresponding to residues 5‐23 of APO‐1. The rabbit Ab reacted with thymocytes from different mouse strains and the extent of binding was correlated with the two known APO‐1 alleles. In addition, the Ab reacted with mouse cell lines expressing mouse APO‐1 mRNA but not with human cell lines. Binding of the Ab to MRL and BALB/c thymocytes was completely blocked by the immunizing peptide. Immunofluorescence analysis of MRL/lpr thymocytes showed that they still express APO‐1 protein at approximately one tenth of the wild‐type expression level on their surface. In addition, in lpr as in wild‐type mice we found a decrease of APO‐1 expression in the more mature thymic compartment. Western blot analysis of whole cell lysates from lpr and wild‐type thymocytes showed that the Ab recognized APO‐1 in both cell types. Approximately 50% of CD3+ splenocytes and 80% of in vitro activated CD3+ cells from wild‐type mice reacted with the Ab, but to a lower extent than thymocytes. The same differential reactivity was found in lpr CD3+ splenocytes. lpr T cells, however, showed a substantially lower level of APO‐1. Thus, the differential expression of APO‐1 on thymic versus peripheral lpr T cells might influence their sensitivity towards APO‐1‐mediated apoptosis.
Reduced development of CD4−8−B220+ T cells but normal autoantibody production in lpr/lpr mice lacking major histocompatibility complex class I molecules
Authors: Ohteki Toshiaki , Iwamoto Masahiro , Izui Shozo , MacDonald H. Robson 
Published: March 2007

AbstractThe lpr gene has recently been shown to encode a functional mutation in the Fas receptor, a molecule involved in transducing apoptotic signals. Mice homozygous for the lpr gene develop an autoimmune syndrome accompanied by massive accumulation of double‐negative (DN) CD4−8−B220+ T cell receptor‐α/β+ cells. In order to investigate the origin of these DN T cells, we derived lpr/lpr mice lacking major histocompatibility complex (MHC) class I molecules by intercrossing them with β2‐microglobulin (β2m)‐deficient mice. Interestingly, these lprβ2m–/– mice develop 13‐fold fewer DN T cells in lymph nodes as compared to lpr/lpr wild‐type (lprWT) mice. Analysis of anti‐DNA antibodies and rheumatoid factor in serum demonstrates that lprβ2m–/– mice produce comparable levels of autoantibodies to lprWT mice. Collectively our data indicate that MHC class I molecules control the development of DN T cells but not autoantibody production in Ipr/lpr mice and support the hypothesis that the majority of DN T cells may be derived from cells of the CD8 lineage.
CD4 T cells inhibit in vivo the CD8‐mediated immune response against murine colon carcinoma cells transduced with interleukin‐12 genes
Authors: Martinotti Alessia , Stoppacciaro Antonella , Vagliani Maddalena , Melani Cecilia , Spreafico Fabio , Wysocka Maria , Parmiani Giorgio , Trinchieri Giorgio , Colombo Mario P. 
Published: March 2007

AbstractRetroviral‐mediated cytokine gene transfer into tumor cells is a highly effective way of inducing tumor inhibition and immunity. We analyzed the tumorigenicity of C‐26 murine colon carcinoma cells transduced with genes encoding the two subunits of murine interleukin‐12 (IL‐12) in a polycistronic retroviral vector and selected for resistance to G418 and for IL‐12 production (30–80 pg/ml). BALB/c mice injected s.c., i.v. and intrasplenically with C‐26/IL‐12 cells from three different IL‐12‐producing clones showed delayed tumor onset as compared with mice injected with control NeoR‐transduced or parental tumor cells. Although C‐26/IL‐12 tumor‐bearing mice eventually died of lung metastasis, their survival time was twice as long as that of mice injected with control cells. In experiments with mice selectively depleted of natural killer (NK) cells before tumor cell injection, the time of tumor onset and survival of mice injected with C‐26/IL‐12 s.c. and i.v., respectively, was reduced. CD8+ T cell depletion had no effect on latency or survival, whereas removal of CD4+ T cells led to C‐26/IL‐12 tumor regression in about 40% of mice. Histological and immunocytochemical characterization of leukocytes infiltrating C‐26/IL‐12 tumors showed only slight infiltration with few T cells in non‐depleted mice but abundant infiltration by CD8+ T cells and asialo‐GM1+ NK cells in tumors of mice depleted of CD4+ T cells. The lack of CD8+ T cell infiltration is not due to a CD4‐mediated suppression of their activation because irradiated C‐26/IL‐12 cells primed for the induction of a strong cytotoxic T lymphocyte response against C‐26 parental cells and induced CD8+ effector cells that protected against C‐26/IL‐12 in a Winn assay. Rather, the results suggest that, although C‐26/IL‐12 cells injected in vivo stimulate both NK and CD8+ T cells, tumor infiltration by the latter is inhibited by CD4+ T cells.
Genes encoded in the major histocompatibility complex affecting the generation of peptides for TAP transport
Authors: Cerundolo Vincenzo , Kelly Adrian , Elliott Tim , Trowsdale John , Townsend Alain 
Published: March 2007

AbstractThe B cell line 721.174 has lost the ability to present intracellular antigens to major histocompatibility complex (MHC) class I‐restricted cytotoxic T lymphocytes (CTL). This phenotype results from a homozygous deletion in the MHC that includes the peptide transporter genes TAP1 and TAP2, and the proteasome subunits LMP2 and LMP7. Recent work has shown that such cells transfected with TAP genes load their class I molecules with endogenous peptides, and present several viral epitopes to class I‐restricted CTL. These data implied that the LMP2 and LMP7 genes were not required for the presentation of most epitopes through class I molecules. By contrast, while confirming the previous reports, we have identified several epitopes that appear to require genes in the MHC in addition to the TAP for their presentation. Further analysis localizes the defect to proteolysis in the cytosol. In one case, presentation could be partially restored by re‐expression of full‐length LMP7. Control experiments with LMP7, from which the putative pro‐region had been removed, failed to restore presentation, and this lack of effect correlated with failure of the shortened LMP7 to incorporate into the proteasome. These results suggest a role for LMP7 in the generation of a viral epitope, but leave open the possibility that additional genes within the .174 deletion are required for full restoration of antigen presentation.
Lipopolysaccharide‐induced interleukin‐10 in mice: role of endogenous tumor necrosis factor‐α
Authors: Barsig Johannes , Küsters Sabine , Vogt Kathrin , Volk Hans‐Dieter , Tiegs Gisa , Wendel Albrecht 
Published: March 2007

AbstractInterleukin (IL)‐10 is known to protect mice against the lethal effects of lipopolysaccharides (LPS) and is considered to be an anti‐inflammatory cytokine which suppresses the production of pro‐inflammatory cytokines. We have examined the interactions of the pro‐inflammatory cytokine tumor necrosis factor‐α (TNF‐α) with IL‐10. Neutralization of TNF‐α in murine bone marrow‐derived macrophages resulted in a significant reduction of LPS‐inducible IL‐10 production. In mice, injection of 5 mg/kg LPS induced circulating IL‐10 with a biphasic time course exhibiting an early peak 1.5 h after challenge (synchronous with TNF‐α) and, after a nadir at 6 h, a second increase between 8 and 12 h. Treatment of mice with neutralizing anti‐mouse TNF‐α antiserum significantly increased LPS‐induced IL‐10 plasma levels between 1.5 and 6 h but diminished those at 12 h, while circulating IL‐6, interferon‐γ (IFN‐γ) and granulocyte colony‐stimulating factor (G‐CSF) concentrations were attenuated overall, without a biphasic response. Analysis of LPS‐induced IL‐10 mRNA expression in different tissues 1 h and 8 h after LPS or LPS plus anti‐TNF‐α revealed that the amount of transcripts in the liver correlated with circulating early and late IL‐10 levels. Our findings suggest that endogenous TNF‐α down‐regulates the early and up‐regulates the late LPS‐induced IL‐10 synthesis in vivo and that the liver is the major source of circulating IL‐10 after stimulation with LPS.
Expression and function of the murine CD95/FasR/APO‐1 receptor in relation to B cell ontogeny
Authors: Onel Karen B. , Tucek‐Szabo Carolyn L. , Ashany Dalit , Lacy Elizabeth , Nikolic‐Zugic Janko , Elkon Keith B. 
Published: March 2007

AbstractMice defective in Fas‐mediated apoptosis (lpr phenotype) have an intrinsic B cell abnormality that predisposes them to autoantibody production. To investigate potential roles for the Fas receptor (FasR) in B cell tolerance, FasR expression and function were evaluated at different stages of B cell development. FasR expression was very low or absent on pro‐ and pre‐B cells, but was detected in early B cell lines and was up‐regulated following IFN‐γ‐induced maturation of the pre‐B cell line 70‐Z. Whereas FasR expression was very low in resting mature sIgM+ B cells, expression was markedly increased following mitogen activation and was also elevated in two mature sIgG+ lymphoma lines. FasR expression correlated strongly with the ability of B cells to undergo Fas‐mediated apoptosis. In addition, although Fas did not appear to play a direct role in apoptosis mediated by cross‐linking of sIg with anti‐IgM, anti‐FasR and sublethal concentrations of anti‐Ig were additive in the induction of apoptosis in the early B cell line WEHI 231. These findings suggest that the Fas pathway is not involved in the elimination of pro‐ and pre‐B cells, but are compatible with an ancillary role for FasR in the elimination of early B cells and elimination of mature B cells following activation.
Characterization of Fcγ receptors on rat mucosal mast cells using a mutant FcϵRI‐deficient rat basophilic leukemia line
Authors: Boček Petr , Dráberová Lubica , Dráber Petr , Pecht Israel 
Published: March 2007

AbstractA novel rat basophilic leukemia (RBL) 2H3 subline of rat mucosal mast cells deficient in the expression of the γ chain (RBL‐γ‐) has permitted functional characterization of their low‐affinity Fcγ receptors (FcγR). A rat FcγRII analog of the mouse b2 isoform has been earlier identified and its transcript detected in RBL‐2H3 cells. We have noew isolated and sequenced the rat FcγRIIb1 isoform and observed differences between its expression in RBL‐2H3 and RBL‐γ‐. Furthermore, we demonstrate that rat mucosal mast cells express a second, low‐affinity Fcγ receptor, namely the FcγRIII. Stimulation of either cell line with IgG complexes decreased the expression of transcripts for all FcγR. Hence, ligation of FcγR on rat mucosal mast cells apparently regulate their transcription. Selective stimulation through the FcγRII or FcγRII/III systems, respectively, was accomplished by either using RBL‐γ‐ line or by saturating the FcγRI on RBL‐2H3 with monomeric IgE. RBL‐γ‐ cells, which do carry FcγRII (but lack FcγRI and FcγRIII), do not respond to IgG (and IgE) immune complexes as monitored by specific protein tyrosine phosphorylation, degranulation or cytokine secretion. This finding, together with the restoration of the functional phenotype of parental cells upon γ chain cDNA transfection into RBL‐γ‐ cells, unequivocally excludes the possible stimulation of rat mucosal mast cells by clustering of their FcγRII. FcϵRI saturation by IgE on parental RBL‐2H3 cells completely blocks their response to IgG immune complexes. Thus the FcγR on these cells do not trigger degranulation and this is not due to the absence of FcγRIII as previously suggested. Therefore, co‐clustering of FcγRII and FcγRIII on rat mucosal mast cells does not seem to stimulate them. A possible inhibitory role of FcγRII in this process is suggested and discussed.
Specific elimination of IgE production using T cell lines expressing chimeric T cell receptor genes
Authors: Lustgarten Joseph , Eshhar Zelig 
Published: March 2007

AbstractB cells that are destined to secrete IgE express a membrane‐bound form of IgE (mIgE) on their cell surface. Thus, elimination of such mIgE‐positive cells should result in the suppression of IgE production, thereby alleviating the symptoms of IgE‐mediated allergy. In this study, we examined, in a model system, whether IgE‐specific effector T cells can be used specifically to eradicate IgE‐producing B cells. To this end, we endowed T cells with anti‐IgE specificity using chimeric T cell receptors (cTCR) containing the variable region domain (Fv) of the 84.1c non‐anaphylactic anti‐mouse IgE monoclonal antibody (mAb). Two configurations of chimeric receptor were used: in the first, we combined the heavy and light variable region chains of 84.1c with the constant (C) regions of the TCR α and β chains. The second construct consisted of a chimeric single‐chain receptor (scFvR), composed of a single‐chain Fv region of the 84.1c antibody and the Cβ domain of the TCR. Following transfection of the cTCR or the scFvR genes into the murine MD.45 cytotoxic T cell hybridoma or the Jurkat human T cell line, functional expression of IgE‐specific chimeric receptors was detected on the cell surface. The transfected cells secreted interleukin‐2 upon stimulation with immobilized IgE or fixed IgE‐producing hybridoma cells. Moreover, cytotoxic T cell hybridomas expressing the chimeric receptor genes specifically eliminated IgE‐secreting B cells in vitro, resulting in isotype‐specific suppression of IgE production.
Natural antibodies against the immunoglobulin F(ab′)2 fragment cause elimination of antigens recognized by the F(ab′)2 from the circulation
Authors: Yano Shinya , Kaku Seiji , Suzuki Ken‐Ichi , Terazaki Chinami , Sakayori Toshiko , Kawasaki Tomihisa , Kawamura Koji , Sugita Yuji , Hoshino Kenji , Masuho Yasuhiko 
Published: March 2007

AbstractA humanized monoclonal IgG1 antibody, designated hC4G1, recognizes the fibrinogen receptor glycoprotein (GP)IIb/IIIa on platelets and inhibits platelet aggregation. When the F(ab′)2 fragment of hC4G1 (F(ab′)2 hC4G1) was administered to cynomolgus monkeys, all the monkeys showed inhibition of platelet aggregation ex vivo. Unexpectedly, a significant decrease in platelet count was observed in 5 of 18 monkeys. Antibodies against F(ab′)2 hC4G1 were detected in the plasma of these monkeys by ELISA. Antibody activity in the plasma of these monkeys was significantly correlated with the intensity of platelet decrease (r = 0.84). The natural monkey antibodies to F(ab′)2 hC4G1 were directed against the C‐terminal region of F(ab′)2 fragment common to all human and humanized IgG antibodies. Natural homo‐reactive antibodies were also detected in human plasma from 15 of 40 healthy volunteers. Specificity was closely similar to that of the monkey antibodies. Affinity‐purified human homo‐reactive antibodies enhanced phagocytosis of platelets treated with the F(ab′)2 hC4G1. Monkey plasma with high homo‐reactive antibody activity was confirmed to decrease platelet count when administered together with F(ab′)2 hC4G1 to a monkey with low antibody activity. These results suggest that F(ab′)2 of humanized and human antibodies causes elimination of the corresponding antigens from the circulation by homo‐reactive antibodies.
Exacerbated autoimmunity associated with a T helper‐1 cytokine profile shift in H‐2E‐transgenic mice
Authors: Takács Katalin , Douek Daniel C. , Altmann Daniel M. 
Published: March 2007

AbstractMajor histocompatibility complex (MHC) class II genes are the strongest susceptibility markers for many human autoimmune diseases. A perplexing aspect of this is that HLA alleles can confer either susceptibility or dominant protection. In nonobese diabetic (NOD) mice, the strongest known diabetes susceptibility locus is within the MHC and is presumed to be the H‐2Ag7 product. When NOD mice carry a transgenic Eαd molecule allowing expression of an H‐2E heterodimer, diabetes is prevented. We investigated whether, as in human auto‐immunity, a single class II heterodimer might protect from some autoimmune diseases while predisposing to others. NOD mice are susceptible to experimental autoimmune encephalomyelitis (EAE) induced by the proteolipoprotein (PLP) epitope 56–70. Susceptibility to EAE was analyzed in NOD mice which either have or lack transgenic H‐2E expression. We found that H‐2E expression in NOD mice has converse effects on diabetes and EAE: while diabetes is prevented, EAE is greatly exacerbated and leads to demyelination. Although PLP 56–70 could be presented both in the context of H‐2A and H‐2E, increased disease severity in H‐2E transgenic mice could not be attributed either to an enhanced T cell proliferative response to PLP or to differences in determinant spread. However, cytokine analysis of the response revealed important differences between NOD mice and their H‐2E transgenic counterparts: H‐2E expression was associated with reduced interleukin‐4 secretion and enhanced interferon‐γ (IFN‐γ) secretion by lymph node cells, while the response of central nervous system infiltrating T cells displayed a markedly enhanced IFN‐γ response. Thus, whether a particular class II molecule confers resistance or susceptibility to an autoimmune disease may depend on differential cytokine profiles elicited by particular class II/autoantigen complexes.