bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ineffective expression of CD40 ligand on cord blood T cells may contribute to poor immunoglobulin production in the newborn
Authors: Brugnoni Duilio , Airò Paolo , Gralfu Daniel , Marconiu Massimo , Lebowitzu Morena , Plebaniu Alessandro , Gilianiu Silvia , Malacarne Fabio , Cattaneo Roberto , Ugaziou Alberto G. , Albertiniu Alberto , Kroczeku Richard A. , Notarangelo Luigi D. 
Published: March 2007

AbstractA major feature of the immature immune system in the newborn is its inability to produce significant levels of immunoglobulins other than IgM in response to antigens. It has recently been demonstrated that interaction of the CD40 molecule on B cells with the CD40 ligand (CD40L) on activated T cells is pivotal for immunoglobulin switching. In view of these findings, we have tested cord blood mononuclear cells (CBMC) for expression of CD40L. Our data clearly demonstrate that freshly isolated CBMC do not express significant levels of CD40L upon in vitro activation; this defect is intrinsic to CD4− cord blood lymphocytes. In vitro priming of CBMC with phytohemagglutinin and interleu‐kin‐2 for several days induced a conversion from the “naive” to the “memory” phenotype (as assessed by expression of CD45 isoforms) and led to substantial CD40L expression upon appropriate restimulation. These data indicate that ineffective CD40L expression might represent a major factor for reduced immunoglobulin production in the neonate, and suggest that antigenic exposure in vivo leads to changes in the genetic program, enabling T cells to express CD40L.
CD14 is expressed and functional in human B cells
Authors: Ziegler‐Heitbrock H. W. Löms , Pechumer Heinrich , Petersmannu Irmhild , Durieuxu Jean‐Jacques , Vitau Natalio , Labetau Mario O. , Ströbelf Marion 
Published: March 2007

AbstractThe human B cell line RPMI 8226 exhibits variable staining with the CD14 antibody My4. We have isolated three stable clones from this line with clones 1 and 2 being My4 positive and clone 3 My4 negative. Similar to previous results in monocytes, immunoprecipitation with the My4 antibody revealed a 54‐kDa cell surface molecule, analysis of supernatants showed soluble CD14, and Northern blotting demonstrated a 1.4‐kb transcript in clones 1 and 2, but not in clone 3, which suggests that the My4 antibody detects CD14 in clones 1 and 2. This CD14 molecule was functional in that lipopolysaccharide stimulation induced interleukin (IL)‐6 and IL‐10 in clones 1 and 2 but not in clone 3. Furthermore, the My4 antibody was capable of blocking these responses at the transcript and protein levels. Finally, peripheral blood B cells were highly purified by cell sorting (> 98% CD19 positive). These cells produced IL‐6 in response to lipopolysaccharide, and this response was blocked by anti‐CD14 antiserum. Thus, our findings demonstrated that human B cells can express functionally active CD14.
Wortmannin, an inhibitor of phospholipase D activation, selectively blocks major histocompatibility complex class II‐restricted antigen presentation
Authors: Carrasco‐Marín Eugenio , Alvarez‐Domínguez Carmen , Leyva‐Cobián Francisco 
Published: March 2007

AbstractWortmannin, a fungal metabolite, is a specific inhibitor of phospholipase D (PLD) activation. Presentation of defined exogenous soluble proteins to specific T cell hybridomas was studied by using different antigen‐presenting cells (APC): IA‐positive peritoneal macrophages (MΦϕ), B lymphoma cells (B) or dendritic cells (DC). Major histocompatibility complex class II‐restricted antigen presentation by MΦϕ was blocked when cells were pretreated with wortmannin. However, when cells constitutively expressing IA molecules (B. DC) were used as APC, no inhibition was observed. Additionally, MHC class I antigen presentation was not impaired by wortmannin. Moreover, wortmannin does not block either peptide presentation or presentation to autoreactive T cells. This effect was time and dose dependent and occurred at the level of intracellular handling of the antigen. Mainly because it was not a toxic inhibition, it was reversible with time and neither antigen uptake and catabolism, nor IA synthesis were affected. Because MΦ, but not B or DC, express PLD activity and only the former were blocked by wortmannin in antigen presentation, our results strongly suggest that a differential antigen‐processing pathway exists in these disparate APC, which could be based essentially on a wortmannin‐sensitive, PLD‐dependent step present in MΦ but absent and/or unnecessary in both B lymphoma cells and DC.
A 150‐kDa molecule of macrophage membrane stimulates interleukin‐2 and interferon‐γ production and proliferation of ovalbumin‐specific CD4+ T cells
Authors: Agrewala Javed N. , Vinay Dass S. , Joshi Aneesh , Mishra Gyan C. 
Published: March 2007

AbstractIn the present study, we describe the potential co‐stimulatory role of a macrophage membrane‐associated protein of 150 kDa (M150). The protein was isolated by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and was found to be a single molecule on two‐dimensional gel electrophoresis. The molecule was re‐constituted in phosphatidyl choline vesicles and tested for its ability to promote the proliferation and the secretion of lymphokines from T helper (Th) cells. The reconstituted M150 induced a significant proliferation of anti‐CD3 monoclonal antibody (mAb)‐stimulated ovalbumin‐specific CD4+ T cells. Further, Th cells activated with this molecule in the presence of anti‐CD3 mAb mainly secreted interleukin (IL)‐2 and interferon‐γ but not IL‐4. M150 could not promote the proliferation of Th cells, or lymphokine secretion in the absence of anti‐CD3 mAb. These observations suggest that M150 acts by selectively activating a Th1‐like immune response.
Ly‐49‐independent inhibition of natural killer cell‐mediated cytotoxicity by a soluble major histocompatibility complex class I molecule
Authors: Roth Claude , Kourilsky Philippe , Ojcius David M. 
Published: March 2007

AbstractNatural killer (NK) cells lyse their targets in a non‐major histocompatibility complex (MHC)‐restricted manner, and the cytotoxicity can be inhibited by a number of MHC class I allele products, suggesting that NK cells may have a “positive receptor” that recognizes the target and a “negative receptort” that receives an inhibitory signal from class I. Since negative receptors could also exert their effect by masking a positive ligand, we have determined whether there may be a direct interaction between class I and an NK surface receptor by measuring cytotoxicity in the presence of a soluble class I molecule, Kd. Soluble Kd at micromolar concentrations could efficiently block NK cell cytotoxicity, suggesting that class I has a direct effect on cytotoxicity, rather than masking another target cell ligand. Inhibition required that Kd be at least divalent, probably because of its higher affinity or its ability to cross‐link the NK surface receptor. In addition, the effect was independent of the peptide used to load Kd, and there was inhibition of cytotoxicity of NK cells derived from either H‐2d or H‐2b mice. Finally, depletion of NK cells expressing Ly‐49 had no effect on the specific inhibition by Kd, raising the possibility that NK cells are endowed with additional negative receptors besides Ly‐49. Taken together, these results suggest that there may be a family of NK receptors recognizing different class I alleles, which can receive negative signals by directly binding to class I on the target cell surface.
An intracisternal A‐particle sequence codes for an antigen recognized by syngeneic cytolytic T lymphocytes on a mouse spontaneous leukemia
Authors: De Bergeyck Vinciane , De Plaen Etienne , Chomez Patrick , Boon Thierry , van Pel Aline 
Published: March 2007

AbstractCytolytic T lymphocyte (CTL) clones directed against spontaneous mouse leukemia LEC have been obtained. By transfecting a cosmid library into cells which were then tested for their ability to stimulate the CTL, we identified the gene coding for the antigen recognized by one of these CTL clones. It is the gag gene of an endogenous defective retrovirus that belongs to the intracisternal A particle (IAP) family. A gag‐encoded nonapeptide presented by the H‐2 Dk molecule caused recognition by the anti‐LEC CTL clone. Southern blot and polymerase chain reaction analyses indicated that the expression of the antigen by the LEC tumor cell line resulted from the transposition of an IAP sequence into a new genomic location.
Response of interleukin‐6‐deficient mice to tumor necrosis factor‐induced metabolic changes and lethality
Authors: Libert Claude , Takahashi Nozomi , Cauwels Anje , Brouckaert Peter , Bluethmann Horst , Fiers Walter 
Published: March 2007

AbstractWhether interleukin (IL)‐6 contributes to tumor necrosis factor (TNF)‐induced lethal shock or whether, on the contrary, it is part of a protective feedback system, remains unresolved. Here, we report experiments with IL‐6 gene‐disrupted mice (IL‐60/0). We have tested the susceptibility of these to TNF‐induced metabolic changes and lethality in different models, and compared the results with those obtained with IL‐6+/+ wild‐type mice. We studied the response to TNF in three different models: (i) murine TNF administration; (ii) TNF in galactosamine (GalN)‐sensitized mice; (iii) TNF in Bacillus Calmette‐Guérin‐sensitized mice. We observed no significant difference between the two types of mice in any of the three models. Furthermore, IL‐60/0 mice could be equally well desensitized (by IL‐1) to TNF/GalN‐induced lethality and tolerized to TNF‐induced shock as IL‐6+/+ mice. We also observed that, in response to turpentine, TNF or IL‐1, IL‐60/0 mice produced significantly less acute phase proteins (APP) than IL‐6+/+ mice. In IL‐60/0 mice, less corticosterone was induced by TNF than in the control mice, while the response to adrenocorticotropic hormone was the same. The results indicate that IL‐6 is not contributing in a major way to the pathogenesis leading to TNF‐induced shock, and that neither IL‐6 nor the APP studied are essential for a protective feedback system.
Recombinant vaccinia viruses expressing interleukin‐5 stimulate an earlier appearance of antibody‐secreting cells in the lung
Authors: Janardhana Vijaya , Andrew Marion , Thomas Sandra , Coupar Barbara 
Published: March 2007

AbstractInterleukin‐5 (IL‐5) is a cytokine that participates in the regulation of antibody secretion, in particular promoting the secretion of IgA at mucosal sites. In this report, recombinant vaccinia viruses expressing IL‐5 have been inoculated into mice and the appearance of antibody‐secreting cells in the spleen and lungs investigated. Although vaccinia virus‐expressed IL‐5 did not increase the level of IgA in serum, antibody‐secreting cells, measured in an enzyme‐linked immunosorbent spot assay, appeared earlier in lungs when the immunizing virus expressed IL‐5. These early B cells secreted either IgM or IgG1.
Certain anti‐CD34 monoclonal antibodies induce homotypic adhesion of leukemic cell lines in a CD18‐dependent and a CD18‐independent way
Authors: Traoré Yves , Hirn Joelle 
Published: March 2007

AbstractCD34 is a highly glycosylated type I membrane protein expressed by early hematopoietic progenitor cells as well as by endothelial cells and a subset of bone marrow stromal cells. CD34 is thought to play an important role during early hematopoiesis, although its function is unknown. We demonstrate that triggering of CD34 results in a rapid and vigorous homotypic adhesion in CD34+ cell lines, thereby providing evidence for a cell‐cell adhesion function of CD34. The cellular adhesion event, induced by only two anti‐CD34 mAb, (Immu‐133 and QBend‐10) was dependent on metabolic energy, an intact cytoskeleton and the presence of divalent cations. Analysis of antibody inhibition experiments indicated that the aggregation process partially involved the CD18 molecule.
B and T lymphocyte subsets enter peripheral lymph nodes and Peyer's patches without preference in vivo: no correlation occurs between their localization in different types of high endothelial venules and the expression of CD44, VLA‐4, LFA‐1, ICAM‐1, CD2 or L‐selectin
Authors: Westermann Jürgen , Nagahori Yutaka , Walter Sebastian , Heerwagen Catharina , Miyasaka Masayuki , Pabst Reinhard 
Published: March 2007

AbstractMany lymphocytes enter tissues such as peripheral lymph nodes and Peyer's patches through high endothelial venules (HEV). It is known that HEV differ in the expression of adhesion molecules as lymphocyte subsets do. Through the interaction of these molecules B and T lymphocyte subsets are thought to be preferentially directed into lymphoid organs. However, it is unclear which role these mechanisms play in vivo, since there are no studies demonstrating that blood lymphocyte subsets preferentially interact with different types of HEV in vivo. Therefore, in the present study the frequency of B, T, CD4+ and CD8+ lymphocytes in the wall of the HEV of rat peripheral lymph nodes and Peyer's patches was analyzed by immunohistology. In addition, the expression of CD44, VLA‐4, LFA‐1, ICAM‐1, CD2 and L‐selectin on B and T lymphocyte subsets of the blood was determined by flow cytometry. Although B and T lymphocytes showed significantly different levels of expression for each adhesion molecule investigated, the relation of B and T lymphocytes within the HEV of peripheral lymph nodes and Peyer's patches was strikingly comparable (38.0 ± 5.2% vs. 40.6 ± 5.7% and 62.0 ± 5.2% vs. 59.4 ± 5.7%, respectively). The same was true for CD4+ and CD8+ cells. Thus, although HEV and the blood lymphocyte subsets differ markedly in their expression pattern of adhesion molecules, the existing levels are sufficient to mediate comparable entrance of B and T lymphocyte subsets into both types of HEV.
Thymic selection and peptide‐induced activation of T cell receptor‐transgenic CD8 T cells in interleukin‐2‐deficient mice
Authors: Krämer Susanne , Mamalaki Clio , Horak Ivan , Schimpl Anneliese , Kioussis Dimitris , Hünig Thomas 
Published: March 2007

AbstractThe requirement for interleukin‐2 (IL‐2) in repertoire selection and peripheral activation of CD8 T cells was tested in mice rendered IL‐2 deficient by gene targeting and expressing a transgenic T cell receptor (TcR) (F5) specific for influenza nucleoprotein (NP) 366‐374 + H‐2Db. Positive selection of the transgenic F5 TcR into the CD8 compartment proceeded normally. Both in vivo and in vitro, the antigenic peptide induced depletion of immature thymocytes and proliferation of mature CD8 T cells regardless of the presence of an intact IL‐2 gene. In contrast, cytotoxic T lymphocyte (CTL) activity was only generated by T cells from IL‐2+ F5 transgenic mice. Exogenous IL‐2 was able to fully restore the CTL response of IL‐2−/− responder cells in vitro. Thus, both in vivo and in vitro, clonal expansion of CD8 T cells can proceed in the absence of IL‐2, whereas in peptide‐immunized F5 transgenic mice, induction of cytotoxic effector function is IL‐2 dependent.
Changes in thymic export of γδ and αβ T cells during fetal and postnatal development
Authors: Witherden Deborah A. , Kimpton Wayne G. , Abernethy Nevin J. , Cahill Ross N. P. 
Published: March 2007

AbstractThe thymus plays an essential role in the generation and selection of T cells and exports approximately 0.5–1% of thymocytes per day in young animals and considerably fewer in older animals. To date there have been no studies directly examining fetal thymic export in any species. Using the technique of intrathymic injection of fluorescein isothiocyanate, followed by an assay for green fluorescent cells in the periphery and for the expression of cell surface antigens on these cells, we have compared directly the export of T cells from the fetal and postnatal ovine thymus. While the thymus exports both αβ and γδ T cells, our results demonstrate that the proportion of thymic γδ T cells that are exported per day is much higher than that of thymic αβ T cells. Moreover, the export rate of γδ T cells increased from approximately 1 in every 60 γδ thymocytes per day emigrating from the fetal thymus to 1 in every 20 from the postnatal thymus. In addition, we identify a population of CD5+CD4−CD8−γδ− T cells emigrating from the fetal thymus but greatly reduced among thymic emigrants after birth. These findings have several implications regarding the mechanisms and control of selection of both γδ and αβ T cells.
In vivo modification of major histocompatibility complex class II DRA promoter occupancy mediated by the AIR‐1 trans‐activator
Authors: Rigaud Gildas , Paiola Fiorenza , Accolla Roberto S. 
Published: March 2007

AbstractRJ 2.2.5 is a human B cell mutant derived from the Burkitt lymphoma Raji cell, which is defective in the AIR‐1 locus function. This locus encodes a transcriptional trans‐activator required for the constitutive expression of major histocompatibility complex (MHC) class II genes. Here we show, by in vivo DNase I footprinting, that the AIR‐1 locus defect correlates with changes in the DRA promoter occupancy. Interestingly, reexpression of human MHC class II genes in RJ 2.2.5 × mouse spleen cell hybrids is associated with partial reversion of DRA promoter occupancy to the Raji pattern. DRA promoter occupancy in other class II‐negative B cell lines, derived from patients with bare lymphocyte syndrome, is drastically different from the one observed in RJ 2.2.5 and Raji cells. Moreover, the use of the DNase I as an in vivo footprinting agent reveals that the patients' cell lines do not display a completely “bare promoter” as previously reported using dimethyl sulfate as the footprinting agent. Thus, the use of DNase I allowed us, for the first time, to correlate the AIR‐1 locus defect with class II promoter occupancy alterations and distinguish these alterations from the ones observed in phenotypically similar but genetically distinct MHC class II‐negative cells.
Localization of the site of the murine IgG1 molecule that is involved in binding to the murine intestinal Fc receptor
Authors: Kim Jin‐Kyoo , Tsen May‐Fang , Ghetie Victor , Ward E. Sally 
Published: March 2007

AbstractSite‐directed mutagenesis of a recombinant Fc hinge fragment has recently been used to localize the site of the murine IgG1 molecule that is involved in the control of catabolism (the “catabolic site”). In the current study, the effects of these CH2 and CH3 domain mutations (Ile 253 to Ala 253, His 310 to Ala 310, Gln 311 to Asn 311, His 433 to Ala 433 and Asn 434 to G1n 434) on intestinal transfer of Fc hinge fragments in neonatal mice have been analyzed. Studies using direct transfer and competition assays demonstrate that the mutations affect the transmission from intestinal lumen into serum in a way that correlates closely with the effects of the mutations on pharmacokinetics. Binding studies of several of the Fc hinge fragments to isolated neonatal brush borders have been used to confirm the in vivo transmission data. These analyses have resulted in the localization of the binding site for the intestinal transfer receptor, FcRn, to specific residues of the murine Fc hinge fragment. These residues are located at the CH2‐CH3 domain interface and overlap with both the catabolic site and staphylococcal protein A (SpA) binding site. The pH dependence of IgG1 or Fc fragment binding to FcRn is consistent with the localization of the FcRn interaction site to a region of the Fc that encompasses two histidine residues (His 310 and His 433). To assess whether one or two FcRn binding sites per Fc hinge are required for intestinal transfer, a hybrid Fc hinge fragment comprising a heterodimer of one Fc hinge with the wild‐type IgG1 sequence and a mutant Fc hinge with a defective catabolic site (mutated at His 310, G1n 311, His 433 and Asn 434) has been analyzed in direct and competition transmission assays. The studies demonstrate that the Fc hybrid is transferred with significantly reduced efficiency compared to the wild type Fc hinge homodimer and indicate that the binding to FcRn, and possibly subsequent transfer, is enhanced by the presence of two FcRn binding sites per Fc hinge fragment.
The efficiency of cysteine‐mediated intracellular retention determines the differential fate of secretory IgA and IgM in B and plasma cells
Authors: Guenzi Silvia , Fra Annamaria , Sparvoli Antonella , Bet Paola , Rocco Mattia , Sitia Roberto 
Published: March 2007

AbstractPrevious studies on IgM secretion demonstrated a role for the μ chain C‐terminal cysteine (Cys575) in preventing the transport of unpolymerized subunits along the secretory pathway. The sequence homology between the C‐terminal tailpieces of μ and α heavy chains prompted us to investigate the role of cysteine‐mediated retention in the control of IgA secretion during B cell development. Similar to IgM, IgA are not secreted by B lymphocytes: the retention mechanism can be reversed by the reducing agent 2‐mercaptoethanol, suggesting that disulfide interchange reactions are involved in the quality control of both IgM and IgA. Yet, α2L2 subunits, but not μ2L2, are secreted constitutively by plasma cells. We demonstrate that the differential retention of IgM and IgA subunits by myeloma transfectants is mainly due to the presence of an acidic residue upstream the α chain C‐terminal cysteine. The regulation of polymeric Ig secretion during B cell development provides an example of how thiol‐mediated quality control can be modulated according to the aminoacidic context surrounding the critical cysteine and to the cell type.
Role of antigen‐presenting cells in the polarized development of helper T cell subsets: evidence for differential cytokine production by Th0 cells in response to antigen presentation by B cells and macrophages
Authors: Duncan David D. , Swain Susan L. 
Published: March 2007

AbstractImmune challenges can elicit polarized responses skewed towards the development of T helper type 1 (Th1) or Th2 T cell subsets. To determine if distinct antigen‐presenting cells (APC) populations might selectively influence Th subset development, we studied the role of two key APC populations, B cells and macrophages, in the differentiation of effector Th populations from naive precursor Th in vitro. Antigen (Ag)‐specific, naive CD4+ T cells were enriched from a mouse strain, AND, bearing a transgenic α/β T cell receptor (TCR) encoding reactivity with pigeon cytochrome c peptide 88‐104. Peptide Ag was used throughout these studies so that differences in the uptake and processing by the two APC populations would not influence the results. Both APC populations, activated B cells and bone marrow‐derived macrophages, supported the development of effector Th having the capacity to secrete high levels of cytokines when restimulated. Regardless of APC population present during effector development, exogenous interferon‐γ (IFN‐γ) and interleukin‐4 (IL‐4) had dominant effects on Th subset development. Thus, with both APC populations, effector Th generated in the presence of IFN‐γ acquired a Th1‐type cytokine profile, Th generated with IL‐4 acquired a Th2‐type cytokine profile, and Th generated without IFN‐γ or IL‐4 acquired a Th0‐type cytokine profile. B cells and macrophages also had equivalent APC function in the restimulation of Th1 and Th2‐like effectors, since only minor differences in cytokine production were noted for these effector populations when restimulated with the two APC populations. However, in 8 of 19 experiments, the Th0‐like effector population generated in the presence of IL‐2 differentially responded to restimulation with B cells and macrophages, secreting significantly more IFN‐γ when restimulated with B cells, and significantly more IL‐4 when restimulated with macrophages. We also found that Th effector populations recultured in IFN‐γ or IL‐4 assumed a more Th1 or Th2‐like phenotype, respectively, regardless of their initial cytokine profile. We conclude that through a subtle capacity to skew cytokine production by a Th0 subset, different APC may selectively influence Th subset development under conditions of prolonged or chronic stimulation in an autocrine fashion.