bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complement C3b fragment covalently linked to tetanus toxin increases lysosomal sodium dodecyl sulfate‐stable HLA‐DR dimer production
Authors: Serra Vincent A. , Cretin François , Pépin Elsa , Gabert Françoise M. , Marche Patrice N. 
Published: March 2007

AbstractProcessing and presentation of covalently linked C3b‐tetanus toxin (TT) complexes, as compared to unlinked C3b + TT, lead to increased T cell proliferation. The aim of this study was to analyze the effect of coupling C3b to TT on the efficiency of TT peptide loading on HLA‐DR1 molecules. In the Epstein‐Barr virus‐transformed B cell line HOM 2, we detected a significant increase of sodium dodecyl sulfate (SDS)‐stable major histocompatibility complex (MHC) class II molecules after exposure to C3b‐TT as compared to unlinked C3b and TT. The ratio of compact form/unbound form (C/U ratio) obtained with C3b‐TT as antigen (Ag) is about twice that obtained with uncomplexed TT + C3b as Ag. Similar results were obtained using HLA‐DR1‐transfected fibroblasts that do not express C3b complement receptors, indicating that the SDS‐stable HLA‐DR1 increase did not result simply from C3b opsonization but rather from a direct effect of C3b‐TT linkage on peptide generation. Exposure of HOM 2 cells to C3b‐TT resulted in an increase in concentration of SDS‐stable HLA‐DR molecules in lysosomes but not in endosomes. Thus, C3b attachment to Ag induces a redistribution of peptide/MHC complex which results in a higher efficiency of Ag presentation by MHC class II molecules.
Strong mucosal adjuvanticity of cholera toxin within lipid particles of a new multiple emulsion delivery system for oral immunization
Authors: Tomasi Maurizio , Dertzbaugh Mark T. , Hearn Thomas , Hunter Robert L. , Elson Charles O. 
Published: March 2007

AbstractCholera toxin (CT) is an effective mucosal adjuvant but causes significant intestinal secretion which limits its usefulness. In the present study we developed a new multiple emulsion (ME) delivery system into which antigen and CT could be incorporated and asked whether CT would retain its mucosal adjuvanticity when sequestered within emulsion particles. ME were selectively taken up into Peyer's patches, and those containing antigen plus CT generated intestinal secretory IgA and serum IgG antibody responses in mice comparable quantitatively and qualitatively to those occurring after oral immunization with soluble antigen plus CT. The ME particles containing CT did not cause intestinal secretion. The adjuvanticity of CT within ME was due to the CT present in the inner aqueous phase of the ME and was lost if CT binding was blocked by pre‐incubation with GM1 ganglioside. Proteins incorporated in ME were protected from external acid, protease, and bile. We conclude that CT sequestered in ME, although unable to bind to the epithelium and thus stimulate intestinal secretion, still retains its mucosal adjuvanticity. Thus, the ability of CT to bind to enterocytes is not obligatory for its mucosal adjuvanticity.
Antigen‐specific and nonspecific deletion of immature cortical thymocytes caused by antigen injection
Authors: Martin Stefan , Bevan Michael J. 
Published: March 2007

AbstractAnalysis of antigen‐induced negative selection of thymocytes in T cell receptor (TCR)‐transgenic mice is complicated by the presence of an antigen‐responsive peripheral T cell compartment. Our experiments address the question of whether and how peripheral T cell activation can affect immature thymocytes. Following three daily injections of peptide antigen into mice expressing a peptide‐specific transgenic TCR and deficient for TAP1, we and others have found profound deletion of the CD4+CD8+ (DP) thymocyte subset. However, our work shows that even though mature CD8+ T cells are inefficiently selected in TAP1‐deficient mice, there was a striking degree of peripheral expansion and activation of CD8+ peripheral T cells. Furthermore, when cells from TCR‐transgenic mice were adoptively transferred, we found that deletion of non‐transgenic DP thymocytes occurred in Thy‐1‐congenic and even more efficiently in TAP1‐deficient recipients after repeated peptide injection resulting in peripheral T cell activation. In the adoptive transfer experiments the degree of deletion of immature bystander thymocytes was decreased upon blocking of TNF. These data show that deletion of DP thymocytes can result from excessive peripheral T cell activation and identify TNF as an important effector molecule for this process. When steps are taken to avoid peripheral T cell activation, peptide antigen can induce TCR‐mediated thymocyte deletion, presumably in the thymus cortex, since injection of TAP1‐deficient TCR‐transgenic mice resulted in deletion of immature DP thymocytes prior to detectable peripheral T cell expansion and activation. This effect was not blocked by inhibiting tumor necrosis factor activity. In addition, DP depletion was seen in the absence of peripheral T cell activation when antibody‐mediated depletion of CD8+ T cells was performed. Our work clearly shows that two mechanisms for deletion of DP thymocytes exist: deletion induced by antigen presentation in the thymus and deletion as a consequence of repeated stimulation of mature peripheral T cells.
Susceptibility to hard metal lung disease is strongly associated with the presence of glutamate 69 in HLA‐DPβ chain
Authors: Potolicchio Ilaria , Mosconi Giovanni , Forni Alessandra , Nemery Benoit , Seghizzi Paolo , Sorrentino Rosa 
Published: March 2007

AbstractClinical, epidemiological and experimental data indicate that inhaled metal dust containing cobalt may produce an interstitial lung disease termed “hard metal disease” (HMD). Some aspects of this pathology such as the lack of correlation with dose exposure, the low frequency of the disease and the presence of T cells in the inflammation site, all suggest the existence of a genetic susceptibility, possibly to an immunological response to cobalt or to self proteins modified by cobalt. Here we report that HMD is strongly associated with residue Glu‐69 of the HLA‐DP beta chain. All patients, except for one with a rare genotype, possessed this marker as compared to 17 out of 35 exposed unaffected individuals (p = 0.0014). These data allow us to genetically distinguish a subgroup of cobalt‐exposed individuals at risk for HMD, independently from the more common allergic reaction.
Activation induces apoptosis in Herpesvirus saimiri‐transformed T cells independent of CD95 (Fas, APO‐1)
Authors: Bröker Barbara M. , Kraft Michael S. , Klauenberg Ulricke , Le Deist Françoise , de Villartay Jean‐Pierre , Fleckenstein Bernhard , Fleischer Bernhard , Meinl Edgar 
Published: March 2007

AbstractSignaling via the T cell receptor (TCR)/CD3 complex of pre‐activated T cells induces apoptosis. Such an activation‐induced cell death (AICD) is thought to play an important role in the regulation of cellular immune responses. In this study we analyzed pathways of AICD by using human T cells transformed by Herpesvirus saimiri. These growth‐transformed T cells show the phenotype of activated mature T cells and continue to express a functionally intact TCR. We show that human H. saimiri‐transformed T cell clones readily undergo cell death upon signaling via the TCR/CD3 complex or via phorbol 12‐myristate 13‐acetate (PMA) + ionomycin. The AICD in H. saimiri‐transformed T cells was detectable a few hours after activation and it was not affected by the presence of interleukin (IL)‐2 or by anti‐CD4 cross‐linking. However, AICD required tyrosine phosphorylation, since it could be blocked by herbimycin A. Cyclosporin A (CsA) did not block the development of AICD, but other consequences of activation in H. saimiri‐transformed T cells like the production of interferon‐γ. Surprisingly, the development of AICD was not reduced by neutralizing antibodies to tumor necrosis factor (TNF)‐α or blocking antibodies directed to CD95 (Fas, APO‐1), although H. saimiri‐transformed T cells were sensitive to CD95 ligation. To confirm that this form of AICD is really independent of CD95, we have established an H. saimiri‐transformed T cell line from a patient with a homozygous deletion in the CD95 gene. This CD95‐deficient T cell line was as sensitive to AICD as other CD95‐expressing H. saimiri‐transformed T cells. In conclusion, we describe here a type of AICD in H. saimiri‐transformed T cells that is independent of CD95 and TNF‐α, not sensitive to CsA, but requires tyrosine phosphorylation. This system should be useful for the investigation of CD95‐independent forms of AICD.
Extracellular HIV‐1 Tat protein activates phosphatidylinositol 3‐ and Akt/PKB kinases in CD4+ T lymphoblastoid Jurkat cells
Authors: Borgatti Paola , Zauli Giorgio , Colamussi Maria Luisa , Gibellini Davide , Previati Maurizio , Cantley Lewis L. , Capitani Silvano 
Published: March 2007

AbstractThe biological basis for the pleiotropic activity of extracellular human immunodeficiency virus (HIV)‐1 Tat protein on lymphoid T cell survival is not well understood. We have here demonstrated that the addition in culture of 0.1–10 nM Tat protein to 36‐h serum‐starved lymphoblastoid Jurkat T cells rapidly stimulates the catalytic activity of phosphatidylinositol 3‐kinase (PI 3‐K). The peak of activation was observed 30 min after Tat addition. Extracellular Tat also stimulated the catalytic activity of the Akt/PKB kinase, a major target of PI 3‐K lipid products. Pretreatment of serum‐starved Jurkat cells with 100 nM wortmannin (WT) or 10 μM LY294002, two unrelated pharmacological inhibitors of PI 3‐K, markedly suppressed the catalytic activity of both PI 3‐K and Akt/PKB in Jurkat cells. Moreover, at low concentrations (0.1–1 nM), extracellular Tat showed a small but reproducible protection of Jurkat cells from apoptosis induced by serum deprivation (p < 0.05), while the combination of Tat plus 100 nM WT significantly (p < 0.05) increased the percentage of apoptosis with respect to cells left untreated or treated with Tat alone. Taken together, these data suggest that the anti‐apoptotic activity of low concentrations of Tat protein on Jurkat cells is mediated by a PI 3‐kinase/Akt pathway.
The central nervous system environment controls effector CD4+ T cell cytokine profile in experimental allergic encephalomyelitis
Authors: Krakowski Michelle L. , Owens Trevor 
Published: March 2007

AbstractIn experimental allergic encephalomyelitis (EAE), CD4+ T cells infiltrate the central nervous system (CNS). We derived CD4+ T cell lines from SJL/J mice that were specific for encephalitogenic myelin basic protein (MBP) peptides and produced both Th1 and Th2 cytokines. These lines transferred EAE to naive mice. Peptide‐specific cells re‐isolated from the CNS only produced Th1 cytokines, whereas T cells in the lymph nodes produced both Th1 and Th2 cytokines. Mononuclear cells isolated from the CNS, the majority of which were microglia, presented antigen to and stimulated MBP‐specific T cell lines in vitro. Although CNS antigen‐presenting cells (APC) supported increased production of interferon (IFN)‐γ mRNA by these T cells, there was no increase in the interleukin (IL)‐4 signal, whereas splenic APC induced increases in both IFN‐γ and IL‐4. mRNA for IL‐12 (p40 subunit) was up‐regulated in both infiltrating macrophages and resident microglia from mice with EAE. We have thus shown that a Th1 cytokine bias within the CNS can be induced by CNS APC, and that IL‐12 is up‐regulated in microglial cells within the CNS of mice with EAE. Microglia may therefore control Th1 cytokine responses within the CNS.
Nitric oxide and the immunomodulation of experimental allergic encephalomyelitis
Authors: Gold Daniel P. , Schroder Kim , Powell Henry C. , Kelly Carolyn J. 
Published: March 2007

AbstractPrevious studies examining the effect of nitric oxide synthase (NOS) inhibition on the course of experimental allergic encephalomyelitis (EAE) have yielded conflicting results. This may relate to the use of nonspecific inhibitors and to differences between active and adoptive EAE. We examined the effect of treatment with L‐N‐(1‐iminoethyl)lysine (L‐NIL), a selective inhibitor of the cytokine‐inducible isoform of NOS, on the clinical course of active and adoptive EAE in Lewis rats. We find that while L‐NIL treatment of recipients is protective in adoptive EAE, treatment of active EAE with L‐NIL leads to a marked accentuation of disease expression. In L‐NIL‐treated animals treated with myelin basic protein/complete Freund's adjuvant (MBP/CFA), disease onset is accelerated and clinical symptoms are more severe. Accentuation of integrated disease scores is seen even if L‐NIL treatment is started 5 days following immunization. The histological findings in involved spinal cords from L‐NIL‐treated animals with active EAE are similar to those from untreated animals with similar clinical scores. L‐NIL treatment of MBP/CFA‐immunized animals does not prevent recovery from clinical symptoms, nor does it allow for reinduction of disease in animals previously immunized with MBP/CFA. Treatment of F344 rats, a strain which is relatively nonsusceptible for EAE, with L‐NIL results in consistent evidence of EAE following immunization with MBP/CFA. These findings, together with our previous work on interstitial nephritis, support a role for endogenously generated NO in immunoregulation of T cell responses following immunization with antigen in CFA, and suggest that inducibility of NOS expression may be an important susceptibility factor for autoimmunity.
Expression of ε germ‐line gene transcripts and mRNA for the ε heavy chain of IgE in nasal B cells and the effects of topical corticosteroid
Authors: Durham Stephen R. , Gould Hannah J. , Thienes Cortlandt P. , Jacobson Mikila R. , Masuyama Keisuke , Rak Sabina , Lowhagen Olle , Schotman Elsa , Cameron Lisa , Hamid Qutayba A. 
Published: March 2007

AbstractWe have studied the expression of the gene encoding the ε heavy chain of IgE in nasal B cells of hayfever patients. We developed probes to detect transcripts of the ε germ‐line gene and the rearranged gene by in situ hybridization of biopsy sections from the nasal mucosa. We compared tissue from hayfever patients out of season with that of normal controls, and also of hayfever patients treated with topical corticosteroid (fluticasone propionate) or placebo for 6 weeks and then challenged with antigen. ε chain mRNA was expressed in an unexpectedly high proportion of nasal B cells of both hayfever patients and normal subjects. However, although similar numbers of B cells were found in both groups, the proportion of cells that express ε chain mRNA was several times higher in the hayfever patients. No transcripts of the ε germ‐line gene were detected in either group before allergen challenge. When hayfever patients were administered antigen locally, early (10–30 min) and late (1–24 h) symptoms ensued. After 24 h, coincident with an increase in the number of cells expressing mRNA for IL‐4 in the tissue, ε germ‐line gene transcripts appeared in the nasal B cells. The induction by allergen of IL‐4 mRNA and ε germ‐line gene transcripts was suppressed by fluticasone propionate treatment. Our results suggest that local IgE synthesis and cytokine regulation of heavy chain switching to IgE occur in the nasal mucosa.
Nitric oxide pathway is induced by FcεRI and up‐regulated by stem cell factor in mouse mast cells
Authors: Bidri Mohamed , Ktorza Sandra , Vouldoukis Ioannis , Le Goff Liliane , Debré Patrice , Guillosson Jean‐Jacques , Arock Michel 
Published: March 2007

AbstractMurine stem cell factor (SCF) induces the differentiation of mucosal mast cells (MMC) into connective tissue mast cells (CTMC) and potentiates mediator release induced by aggregation of high‐affinity IgE receptors (FcεRI). In the present work, we investigated the effect of FcεRI aggregation on nitric oxide (NO) pathway induction in the different subsets of mast cells, as well as the contribution of SCF in this induction. Inducible NO synthase (iNOs) expression was not evidenced in non‐stimulated MMC obtained by culture of hematopoietic progenitors in the presence of interleukin‐3, whereas IgE‐antigen‐stimulated MMC expressed iNOs mRNA and protein and synthesized nitrites. Long‐term treatment of MMC with SCF, allowing them to differentiate into CTMC, induced iNOs expression in non‐stimulated cells and up‐regulated iNOs expression and generation of NO derivatives induced by IgE‐antigen stimulation. Thus, NO derivatives generated by mast cells could participate in inflammatory reactions during allergic stimulation.
Expression and function of NKRP1A molecule on human monocytes and dendritic cells
Authors: Poggi Alessandro , Rubartelli Anna , Moretta Lorenzo , Zocchi Maria Raffaella 
Published: March 2007

AbstractIn this study, we analyzed the expression and function of the lymphocyte surface lectin NKRP1A on peripheral blood monocytes (Mo) or Mo and dendritic cells (DC) derived from thymic and bone marrow precursors. De novo expression of NKRP1A and CD14 molecules was detected upon culture of CD2− CD3− CD14− CD16− CD1a− NKRP1A− immature thymic precursors for 7 days in the presence of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF). Under these culture conditions, by day 21, a fraction of cells had lost CD14 and acquired both CD80 (B7.1) and CD86 (B7.2) molecules. These cells displayed a DC‐like morphology and were surface NKRP1A positive. CD34+ NKRP1A− CD14− precursors, isolated from bone marrow and cultured in the presence of GM‐CSF, also expressed both NKRP1A and CD14: these antigens were newly expressed on about one third of cells which had lost the CD34 precursor marker. In addition, NKRP1A was constitutively present on resting CD14+ peripheral blood Mo. When these cells were cultured in the presence of GM‐CSF, the resulting DC population retained the expression of NKRP1A and acquired CD80, while they lost the CD14 antigen. Functional analysis revealed that the engagement of NKRP1A molecule leads to a strong intracellular calcium ([Ca2+]i) increase both in resting peripheral blood Mo and in vitro‐derived DC. [Ca2+]i increase was mainly due to extracellular calcium influx, as it was completely abrogated by the addition of EGTA. More importantly, the engagement of the NKRP1A molecule induced interleukin (IL)‐1β and IL‐12 production by resting Mo and DC, respectively. Altogether these data indicate that NKRP1A lectin is present at the surface of Mo and DC and may play a relevant role in the activation and function of both cell types.
Analysis of the tyrosine phosphorylation and calcium fluxing of human CD6 isoforms with different cytoplasmatic domains
Authors: Kobarg Jörg , Whitney Gena S. , Palmer Dawn , Aruffo Alejandro , Bowen Michael A. 
Published: March 2007

AbstractCD6 is a cell surface glycoprotein that functions both as a co‐stimulatory and adhesion receptor on T cells. Recently we have described CD6 isoforms (CD6a, b, c, d, e) that arise via alternative splicing of exons encoding the cytoplasmic region of the molecule. CD6 becomes phosphorylated on tyrosine (Tyr) residues following stimulation through the T cell receptor (TCR) complex. Since the phosphorylation of Tyr residues renders some cell surface receptors competent for interactions with proteins of intracellular signaling pathways, we wanted to determine which region(s) and residues in the cytoplasmic domain of CD6 were important for phosphorylation on Tyr residues. We engineered and stably expressed chimeric receptors that consisted of the extracellular region of mouse CD6 and the cytoplasmic regions of either naturally occurring isoforms of human CD6, truncated proteins, or point mutants. We were able to demonstrate that of the nine Tyr residues in the cytoplasmic domain of the largest isoform CD6a, the two C‐terminal Tyr residues (Tyr 629/662) are critical for the phosphorylation of CD6 following TCR cross‐linking. Isoform CD6e, which is missing a region that contains two proline‐rich motifs, is not phosphorylated. We further analyzed the ability of the different CD6 isoforms and truncated receptors to mobilize intracellular calcium after CD6/TCR co‐ligation. All CD6 isoforms, including CD6e, as well as the truncation mutant Δ 555, which is missing approximately the C‐terminal half of the cytoplasmic domain, are able to increase Ca2+ influx. Taken together, these results suggest that the region of CD6 which is critical for Ca2+ mobilization is located N‐terminal from amino acid 555 and is therefore different from the region located at the C terminus of CD6, which is necessary for tyrosine phosphorylation.
Identification of a homolog of the Cα3′/hs3 enhancer and of an allelic variant of the 3′IgH/hs1,2 enhancer downstream the human immunoglobulin α1 gene
Authors: Pinaud Eric , Aupetit Corinne , Chauveau Christine , Cogné Michel 
Published: March 2007

AbstractAlthough four regulatory elements are known downstream the mouse IgH α gene, a single enhancer homologous to hs1,2 has been thus far described downstream each human α gene (Chen, C. and Birshtein, B. K., J. Immunol. 1997. 159: 1310). We characterized a 10‐kb region downstream the human α1 gene. Two B cell‐specific regulatory elements homologous to the murine Cα3′/hs3 and hs1,2 3′ enhancers were found, which are duplicated downstream α2. The hs1,2 element is in inverted orientation by comparison with a recently reported α1 hs1,2 element: it appears as a common allelic variant carrying an internal tandem repeat insertion and its prevalence in the human population is 60%. As in the mouse, the human hs1,2 enhancer is flanked with long inverted repeats which may have promoted inversion events through homologous recombination. Although the palindromic organization of the region is maintained in human, sequence identity with rodents focuses on core enhancer elements rather than on flanking repeats. Concerted divergence of both sides of the dyad symmetry suggests that inverted repeats are not just evolutionary remnants but rather play an architectural role in the LCR function.
Conservation of a master hematopoietic switch gene during vertebrate evolution: Isolation and characterization of Ikaros from teleost and amphibian species
Authors: Hansen John D. , Strassburger Pamela , Du Pasquier Louis 
Published: March 2007

AbstractThe generation of T, B and NK lymphocyte lineages from pluripotent hematopoietic stem cells is dependent upon the early expression of the Ikaros locus which by means of alternative splicing produces a variety of zinc finger DNA binding transcription factors. We assessed the general biological importance of Ikaros by studying its conservation and expression in teleost fish and amphibians. Portions of Ikaros cDNA from rainbow trout and Xenopus were amplified by reverse transcription‐polymerase chain reaction (RT‐PCR). They show roughly 75% conservation of the amino acid sequence with mammalian Ikaros. The trout fragment was then used to isolate full‐length Ikaros clones from a trout thymocyte cDNA library. In mice and humans, Ikaros produces six alternatively spliced isoforms, but in trout two additional novel splice variants designated Ik‐7 and Ik‐8 were also found. Ik‐7 is expressed in a similar fashion to Ik‐1 and Ik‐2, the predominant isoforms expressed in mammalian lymphocytes. In trout and zebrafish, as in mammals, Ikaros is a single‐copy gene, but in Xenopus segregation analysis demonstrates that Ikaros has been duplicated, most likely a result of polyploidization. We then examined the expression of Ikaros in trout and Xenopus tumor T cell lines via Northern blot, RT‐PCR, immunofluorescence and Western blot analysis. Overall, Ikaros is expressed in a lymphoid‐specific fashion similar to that found in mice and humans. In addition Ikaros is expressed early in trout ontogeny, beginning roughly at days 3–4 in the yolk sac and at day 5–6 in the embryo proper. The conservation of Ikaros structure and expression confirms it as a master switch of hematopoiesis.