bluuebunny/crossref_metadata_2025 huggingface dataset:
Generation of immunoglobulin light chain gene diversity in Raja erinacea is not associated with somatic rearrangement, an exception to a central paradigm of B cell immunity.
Authors: Anderson M K , Shamblott M J , Litman R T , Litman G W
Published: June 2004

In all vertebrate species examined to date, rearrangement and somatic modification of gene segmental elements that encode portions of the antigen-combining sites of immunoglobulins are integral components of the generation of antibody diversity. In the phylogenetically primitive cartilaginous fishes, gene segments encoding immunoglobulin heavy and light chain loci are arranged in multiple clusters, in which segmental elements are separated by only 300-400 bp. In some cases, segmental elements are joined in the germline of nonlymphoid cells (joined genes). Both genomic library screening and direct amplification of genomic DNA have been used to characterize at least 89 different type I light chain gene clusters in the skate, Raja. Analyses of predicted nucleotide sequences and predicted peptide structures are consistent with the distribution of genes into different sequence groups. Predicted amino acid sequence differences are preferentially distributed in complementarity-determining versus framework regions, and replacement-type substitutions exceed neutral substitutions. When specific germline sequences are related to the sequences of individual cDNAs, it is apparent that the joined genes are expressed and are potentially somatically mutated. No evidence was found for the presence of any type I light chain gene in Raja that is not germline joined. The type I light chain gene clusters in Raja appear to represent a novel gene system in which combinatorial and junctional diversity are absent.
T cell receptor gene recombination patterns and mechanisms: cell death, rescue, and T cell production.
Authors: Petrie H T , Livak F , Burtrum D , Mazel S
Published: June 2004

The antigen-specific receptors of T and B lymphocytes are generated by somatic recombination between noncontiguous gene segments encoding the variable portions of these molecules. The semirandom nature of this process, while desirable for the generation of diversity, has been thought to exact a high price in terms of sterile (out-of-frame) products. Historically, the majority of T lymphocytes generated in mammals were thought to be useless, either because they generated such sterile rearrangements or because the receptors generated did not appropriately recognize self-molecules (i.e., positive and negative selection). In the studies described here, we characterize the onset of T cell receptor (TCR) alpha and beta chain gene rearrangements and quantitate their progression throughout T cell development. The results show that T cell production efficiency is enhanced through (a) rearrangement of TCR-beta chain genes early during T cell development, with selective expansion of those cells possessing in-frame rearrangements; (b) deletion of sterile rearrangements at the TCR-alpha chain locus through ordered (proximal to distal) sequential recombination; and (c) modification of nonselectable alpha/beta heterodimer specificities through generation and expression of new TCR-alpha chains. In addition, we demonstrate strict correlations between successful TCR-beta gene rearrangement, the onset of TCR-alpha gene rearrangement, rapid cell division, and programmed cell death, which together serve to maintain cell turnover and homeostasis during T cell development.
Activation of Raf-1 and mitogen-activated protein kinase in murine macrophages partially mimics lipopolysaccharide-induced signaling events.
Authors: Hambleton J , McMahon M , DeFranco A L
Published: June 2004

Lipopolysaccharide (LPS), a highly conserved component of the outer membrane of gram-negative bacteria, stimulates macrophages to release various cytokine and eicosanoid mediators of the immune response. The mechanism by which LPS stimulates these cells is poorly characterized. One of the most rapid LPS-stimulated events is the phosphorylation and activation of the p42 and p44 isoforms of mitogen-activated protein (MAP) kinase. We wished to examine the role of MAP kinase in LPS-induced signaling in murine macrophages by activating MAP kinase independently of LPS. An expression vector encoding a Raf-1:estrogen receptor (ER) chimeric protein was transfected into the murine macrophage cell line RAW 264.7. Activation of this chimeric protein (delta Raf-1:ER) by estradiol resulted in rapid and prolonged activation of MAP kinase, as expected from previous results implicating Raf-1 as an upstream activator of this signaling cascade. LPS stimulation induced accumulation of MAP kinase phosphatase 1 messenger RNA, whereas delta Raf-1:ER activation did not, perhaps accounting for the more prolonged activation of MAP kinase seen in response to delta Raf-1:ER activation. Similarly, activation of DNA binding by the transcription factor, nuclear factor (NF) kappa B, as assessed by electrophoretic mobility shift assay, occurred in response to LPS stimulation but not in response to delta Raf-1:ER activation or phorbol myristate acetate (PMA) stimulation. Using an enzyme-linked immunosorbent assay for murine tumor necrosis factor alpha (TNF-alpha), we found that LPS and PMA stimulation and delta Raf-1:ER activation induced secretion of TNF-alpha, although the amount of TNF-alpha secreted in response to delta Raf-1:ER activation and PMA stimulation was approximately 20-fold less than that secreted in response to LPS. Correspondingly, accumulation of TNF-alpha messenger RNA was weakly induced by delta Raf-1:ER activation or PMA stimulation, whereas strong induction was noted in response to LPS. These results suggest that Raf-1 or PMA activation of MAP kinase in murine macrophages is sufficient for a small amount of TNF-alpha production and secretion in the absence of NF-kappa B activation, but LPS stimulation involves additional signaling events, such as NF-kappa B activation, that augment the response seen with activation of MAP kinase alone.
Human interferon-inducible protein 10 is a potent inhibitor of angiogenesis in vivo.
Authors: Angiolillo A L , Sgadari C , Taub D D , Liao F , Farber J M , Maheshwari S , Kleinman H K , Reaman G H , Tosato G
Published: June 2004

Human interferon-inducible protein 10 (IP-10), a member of the alpha chemokine family, inhibits bone marrow colony formation, has antitumor activity in vivo, is chemoattractant for human monocytes and T cells, and promotes T cell adhesion to endothelial cells. Here we report that IP-10 is a potent inhibitor of angiogenesis in vivo. IP-10 profoundly inhibited basic fibroblast growth factor-induced neovascularization of Matrigel (prepared by H. K. Kleinman) injected subcutaneously into athymic mice. In addition, IP-10, in a dose-dependent fashion, suppressed endothelial cell differentiation into tubular capillary structures in vitro. IP-10 had no effect on endothelial cell growth, attachment, and migration as assayed in vitro. These results document an important biological property of IP-10 and raise the possibility that IP-10 may participate in the regulation of angiogenesis during inflammation and tumorigenesis.
Cooperativity between the J and S elements of class II major histocompatibility complex genes as enhancers in normal and class II-negative patient and mutant B cell lines.
Authors: Sugawara M , Scholl T , Mahanta S K , Ponath P D , Strominger J L
Published: June 2004

The class II major histocompatibility complex genes all contain in their proximal promoters three cis-elements called S, X, and Y that are conserved in both sequence and position, and a fourth element, J, conserved in sequence but not in position. J, X, and Y and, to some extent, S, have been shown to be functionally important in regulation of expression of these genes. In the present study, a protein factor that binds cooperatively to the S plus J elements of the promoter of the class II major histocompatibility complex gene DPA has been detected. Moreover, functional cooperativity between S and J in activation of the enhancerless -40 interferon-beta (-40 IFN-beta) promoter has been demonstrated. Finally, the latter assay appears to subdivide complementation group A of class II negative human B cell lines that includes both mutants generated in vitro and cells from patients with the bare lymphocyte syndrome (type II). In three of these cell lines, the enhancerless -40 IFN-beta promoter containing the S plus J elements was functionally active, while in the others it was inactive.
The immediate phase of c-kit ligand stimulation of mouse bone marrow-derived mast cells elicits rapid leukotriene C4 generation through posttranslational activation of cytosolic phospholipase A2 and 5-lipoxygenase.
Authors: Murakami M , Austen K F , Arm J P
Published: June 2004

c-kit ligand (KL) activated mouse bone marrow-derived mast cells (BMMC) for the dose- and time-dependent release of arachidonic acid from cell membrane phospholipids, with generation of leukotriene (LT) C4 in preference to prostaglandin (PG)D2. KL at concentrations of 10 ng/ml elicited half-maximal eicosanoid generation and at concentrations of > 50 ng/ml elicited a maximal generation of approximately 15 ng LTC4 and 1 ng PGD2 per 10(6) cells, with 20% net beta-hexosaminidase release 10 min after stimulation. Of the other cytokines tested, none, either alone or in combination with KL, elicited or modulated the immediate phase of mediator release by BMMC, indicating strict specificity for KL. Activation of BMMC in response to KL was accompanied by transient phosphorylation of cytosolic phospholipase A2 and reversible translocation of 5-lipoxygenase to a cell membrane fraction 2-5 min after stimulation, when the rate of arachidonic acid release and LTC4 production were maximal. BMMC continuously exposed to KL in the presence of IL-10 and IL-1 beta generated LTC4 in marked preference to PGD2 over the first 10 min followed by delayed generation of PGD2 with no LTC4 over several hours. Pharmacologic studies revealed that PGD2 generation in the immediate phase depended on prostaglandin endoperoxide synthase (PGHS)-1 and in the delayed phase on PGHS-2. Thus, KL provided a nonallergic stimulus for biphasic eicosanoid generation by mast cells. The immediate phase is dominated by LTC4 generation with kinetics and postreceptor biosynthetic events similar to those observed after cell activation through the high affinity IgE receptor, whereas the delayed phase of slow and selective PGD2 production is mediated by induction of PGHS-2.
Self tolerance to T cell receptor V beta sequences.
Authors: Falcioni F , Vidović D , Ward E S , Bolin D , Singh G , Shah H , Ober B , Nagy Z A
Published: June 2004

T cell tolerance to self is achieved by deletion or inactivation of clones recognizing peptides of self proteins presented by major histocompatibility complex molecules. A considerable fraction of self proteins accessible to the immune system is contributed by the system itself, for example, the receptors used for antigen recognition (antibodies and T cell receptors [TCRs]). Thus far, it has remained unclear, whether antigen receptors are subject to self tolerance, or on contrary, engage into network interactions implying immunity rather than tolerance. In this study, we demonstrate self tolerance to synthetic peptides corresponding to the first hypervariable region of the V beta 8.1 and V beta 8.2 TCR proteins. We also show that the tolerogenic synthetic peptide corresponds to a fragment produced by processing of the V beta protein, and conversely, that a V beta peptide not produced by processing is also not subject to self tolerance. Thus, the rules of tolerance seem to apply to antigen receptors, at least to their germline-encoded portions, in a similar fashion as to other self proteins. This finding has important implications for studies of natural and artificially induced immune networks.
Bone marrow-generated dendritic cells pulsed with a class I-restricted peptide are potent inducers of cytotoxic T lymphocytes.
Authors: Porgador A , Gilboa E
Published: June 2004

It has previously been shown that bone marrow-generated dendritic cells (DC) are potent stimulators in allogeneic mixed leukocyte reactions and are capable of activating naive CD4+ T cells in situ in an antigen-specific manner. In this study we have investigated whether bone marrow-generated DC are capable of inducing antigen-specific CD8+ T cell responses in vivo. Initial attempts to induce specific cytotoxic T lymphocyte (CTL) responses in mice injected with bone marrow-generated DC pulsed with ovalbumin (OVA) peptide were frustrated by the presence of high levels of nonspecific lytic activity, which obscured, though not completely, the presence of Ag-specific CTL. Using conditions that effectively differentiate between antigen-specific and nonspecific lytic activity, we have shown that bone marrow-generated DC pulsed with OVA peptide are potent inducers of OVA-specific CTL responses in vivo, compared with splenocytes or RMA-S cells pulsed with OVA peptide, or compared with immunization with free OVA peptide mixed with adjuvant. Antibody-mediated depletion experiments have shown that the cytotoxic effector cells consist primarily of CD8+ cells, and that induction of CTL in vivo is dependent on CD4+ as well as on CD8+ T cells. These results provide the basis for exploring the role of bone marrow-generated DC in major histocompatibility class I-restricted immune responses, and they provide the rationale for using bone marrow-generated DC in CTL-mediated immunotherapy of cancer and infectious diseases.
Triglyceride-rich lipoproteins prevent septic death in rats.
Authors: Read T E , Grunfeld C , Kumwenda Z L , Calhoun M C , Kane J P , Feingold K R , Rapp J H
Published: June 2004

Triglyceride-rich lipoproteins bind and inactive bacterial endotoxin in vitro and prevent death when given before a lethal dose of endotoxin in animals. However, lipoproteins have not yet been demonstrated to improve survival in polymicrobial gram-negative sepsis. We therefore tested the ability of triglyceride-rich lipoproteins to prevent death after cecal ligation and puncture (CLP) in rats. Animals were given bolus infusions of either chylomicrons (1 g triglyceride/kg per 4 h) or an equal volume of saline for 28 h after CLP. Chylomicron infusions significantly improved survival (measured at 96 h) compared with saline controls (80 vs 27%, P < or = 0.03). Chylomicron infusions also reduced serum levels of endotoxin, measured 90 min (26 +/- 3 vs 136 +/- 51 pg/ml, mean +/- SEM, P < or = 0.03) and 6 h (121 +/- 54 vs 1,026 +/- 459 pg/ml, P < or = 0.05) after CLP. The reduction in serum endotoxin correlated with a reduction in serum tumor necrosis factor, measured 6 h after CLP (0 +/- 0 vs 58 +/- 24 pg/ml, P < or = 0.03), suggesting that chylomicrons improve survival in this model by limiting macrophage exposure to endotoxin and thereby reducing secretion of inflammatory cytokines. Infusions of a synthetic triglyceride-rich lipid emulsion (Intralipid; KabiVitrum, Inc., Alameda, CA) (1 g triglyceride/kg) also significantly improved survival compared with saline controls (71 vs 27%, P < or = 0.03). These data demonstrate that triglyceride-rich lipoproteins can protect animals from lethal polymicrobial gram-negative sepsis.
Human autoantibody to defensin: disease association with hyperreactive onchocerciasis (sowda).
Authors: Gallin M Y , Jacobi A B , Büttner D W , Schönberger O , Marti T , Erttmann K D
Published: June 2004

Chronic hyperreactive onchodermatitis (sowda) is a severe form of onchocerciasis observed in a subset of individuals infected with the filarial nematode Onchocerca volvulus. SDS-PAGE and immunoblot analyses of O. volvulus adult worm extracts were used to characterize the antigens of the marked antibody response of sowda patients. One 2.5-kD antigen was recognized by sera from all 35(100%) sowda patients that were studied. In comparison, only 7 of 44 (16%) patients with generalized onchocerciasis and 11 of 21 (52%) of exposed individuals with no microfilariae in skin snips and no signs of disease showed reactivity to this antigen. Microfilaricidal treatment of sowda patients with improvement of the clinical status was associated with a decrease or disappearance of antibodies to the 2.5-kD antigen. Amino acid sequencing of the antigen indicated identity to human defensins 1-3 of neutrophils. Defensin was demonstrated by immunohistochemical staining in onchocercal nodules on the surface of adult filariae and in the surrounding tissue. A similar staining pattern was observed for other proteins present in neutrophils such as myeloperoxidase, elastase, and the L-1 protein complex (MRP 8/MRP 14), indicating that neutrophils, macrophages, and their proteins predominate in the environment adjacent to the worms. These results demonstrate an association between the presence of autoantibodies to defensins and an infectious disease of known etiology. The association with a particular form of onchocerciasis, sowda, suggests a link between formation of autoantibodies to defensin and enhanced immune reactivity towards the parasite.
GD2 oligosaccharide: target for cytotoxic T lymphocytes.
Authors: Zhao X J , Cheung N K
Published: June 2004

Carbohydrate antigens rarely provide target epitopes for cytotoxic T lymphocytes (CTL). Disialoganglioside GD2 is a glycolipid expressed at high levels in human tumors and a small group of murine lymphomas (EL4, RBL5, RMA, RMA-S, A13, and BALBRVE). Immunization of C57B1/6 mice with irradiated EL4 cells stimulated a specific CTL response and protected these animals from engraftment of EL4 lymphoma. The CTL activity resided in the CD4-CD8+ population, was dependent on T cell receptor alpha/beta, and was not removed by anti-natural killer cell immunoabsorption, but was restricted to GD2 and H-2b bearing targets. CTL activity could be completely inhibited by GD2-oligosaccharide-specific monoclonal antibodies and their F(ab')2 fragments, but not by immunoglobulin G3 myelomas or antibodies against GD3 or GM2. Soluble GD2 did not inhibit specific tumor lysis. RMA-S lymphoma cells (GD2+H-2b-TAP2 deficient) were resistant to GD2-specific CTL. Sialic acid-containing peptides eluted from EL4 lymphoma cells could (a) stabilize H-2 molecules on RMA-S cells and (b) sensitize them for GD2-specific CTL. Control peptides (derived from vesicular stomatitis virus nucleoprotein peptide and GD2-negative lymphomas) could also stabilize H-2 on RMA-S, but were resistant to GD2-specific CTL. These H-2-binding peptides could be purified by anti-GD2 affinity chromatography. We postulate a new class of naturally occurring epitopes for T cells where branched-chain oligosaccharides are linked to peptides with anchoring motifs for the major histocompatibility complex class I pocket. While analogous to the haptens trinitrophenyl and O-beta-linked acetyl-glucosamine, the potential implications of natural carbohydrates as antigenic epitopes for CTL in biology are considerable.
Functional evidence for epitope spreading in the relapsing pathology of experimental autoimmune encephalomyelitis.
Authors: McRae B L , Vanderlugt C L , Dal Canto M C , Miller S D
Published: June 2004

The role of epitope spreading in the pathology of relapsing-remitting experimental autoimmune encephalomyelitis (R-EAE) was examined. Using peripherally induced immunologic tolerance as a probe to analyze the neuropathologic T cell repertoire, we show that the majority of the immunopathologic reactivity during the acute phase of R-EAE in SJL/J mice induced by active immunization with the intact proteolipid (PLP) molecule is directed at the PLP139-151 epitope and that responses to secondary encephalitogenic PLP epitopes may contribute to the later relapsing phases of disease. Intermolecular epitope spreading was demonstrated by showing the development of T cell responses to PLP139-151 after acute disease in mice in which R-EAE was initiated by the transfer of T cells specific for the non-cross-reactive MBP84-104 determinant. Intramolecular epitope spreading was demonstrated by showing that endogenous host T cells specific for a secondary encephalitogenic PLP epitope (PLP178-191) are demonstrable by both splenic T cell proliferative and in vivo delayed-type hypersensitivity responses in mice in which acute central nervous system damage was initiated by T cells reactive with the immunodominant, non-cross-reactive PLP139-151 sequence. The PLP178-191-specific responses are activated as a result of and correlate with the degree of acute tissue damage, since they do not develop in mice tolerized to the initiating epitope before expression of acute disease. Most importantly, we show that the PLP178-191-specific responses are capable of mediating R-EAE upon adoptive secondary transfer to naive recipient mice. Furthermore, induction of tolerance to intact PLP (which inhibits responses to both the initiating PLP139-151 epitope and to the PLP178-191 epitope) after the acute disease episode is sufficient to prevent relapsing disease. These results strongly support a contributory role of T cell responses to epitopes released as a result of acute tissue damage to the immunopathogenesis of relapsing clinical episodes and have important implications for the design of antigen-specific immunotherapies for the treatment of chronic autoimmune disorders in humans.
Cloning and functional characteristics of murine large granular lymphocyte-1: a member of the Ly-49 gene family (Ly-49G2)
Authors: Mason L H , Ortaldo J R , Young H A , Kumar V , Bennett M , Anderson S K
Published: June 2004

Large granular lymphocyte (LGL) 1 is a cell surface glycoprotein expressed on a subset (50%) of C57BL/6 natural killer (NK) cells. Immunoprecipitation experiments reveal that the LGL-1 protein exists as a disulfide-linked 40-kD homodimer. Functional studies of LGL-1+ cells indicate that selected H-2d target cells are not lysed efficiently by these interleukin (IL)-2-cultured NK cells. These findings suggested that LGL-1 may be a member of the Ly-49 gene family. Here we report the molecular cloning of the LGL-1 cDNA from a severe combined immunodeficient-adherent lymphokine-activated killer cell library transfected into Cos-7 cells and find LGL-1 to be homologous to the Ly-49 gene at both the nucleotide (85%) and amino acid levels (73%). Sequencing of our LGL-1 cDNA has revealed it to be nearly identical to the Ly-49G2 cDNA recently isolated by cross-hybridization with an Ly-49 probe. LGL-1 represents a type II transmembrane protein of 267 amino acids with its carboxyl end exposed extracellularly. The LGL-1 protein contains 11 highly conserved cysteine residues and a 25-amino acid transmembrane region. Southern blot analysis demonstrates that there are a number of homologous genes in mouse DNA that hybridize strongly to LGL-1. Northern analyses using poly A+ RNA from LGL-1+ NK cells indicate that LGL-1 is expressed as a 1.4 kb mRNA. Two-color flow cytometry analysis (FCA) of C57BL/6 splenic NK cells demonstrates that LGL-1 and Ly-49 label overlapping subsets of cells. FCA identifies four subsets of NK cells as defined by LGL-1 versus Ly-49 staining. We have sorted these individual subsets, expanded them in IL-2, and performed cytotoxicity experiments to determine their target cell profiles in relation to class I expression. Results of these studies are complex, but indicate that Ly-49 may not be the only molecule that recognizes class I as an inhibitory signal for cytotoxicity. LGL-1+ cells also fail to lyse several H-2d-expressing tumor targets and concanavalin A lymphoblasts from BALB/c but not C57BL/6 mice. This inhibition of lysis by LGL-1+ NK cells is negated by addition of monoclonal antibody (mAb) 4D11 that recognizes the LGL-1 protein. When mAbs to the class I molecules H-2Dd and H-2Ld (alpha 1 alpha 2 domains only) are added to cytotoxicity assays, LGL-1+ cells lyse H-2d targets very effectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Cloning and characterization of 5E6(Ly-49C), a receptor molecule expressed on a subset of murine natural killer cells.
Authors: Stoneman E R , Bennett M , An J , Chesnut K A , Wakeland E K , Scheerer J B , Siciliano M J , Kumar V , Mathew P A
Published: June 2004

5E6 is a cell surface molecule expressed on a subpopulation of murine natural killer (NK) cells that are involved in the specific rejection of H-2d or H-2f (hemopoietic histocompatibility determinant 2) bone marrow cell grafts. Here, we isolated and cloned the gene encoding 5E6 and determined the nucleotide sequence of the cDNA. 5E6 is nearly identical to Ly-49C; the deduced amino acid sequence reveals a polypeptide of 266 amino acids with a molecular weight of 31,284 that contains multiple cysteine residues to explain its disulfide-linked homodimer structure and five potential N-linked glycosylation sites. 5E6 is a type II integral membrane protein with an extracellular carbohydrate recognition domain characteristic of C-type (Ca(2+)-dependent) animal lectins. Chromosomal mapping indicates that 5E6 is located within the NK gene complex on chromosome 6. The sequence of 5E6 mRNA and the degree of glycosylation of 5E6 protein are under genetic control. Immunoprecipitation before removal of N-linked sugars reveals different size molecules. There are several nucleotide differences among BALB/c, B6, and NZB mRNAs; however, none of them would be expected to affect N-glycosylation. Of particular interest are two findings: (a) BALB/c, B6, and (BALB/c x B6)F1 5E6 reduced molecules are approximately 65, 54, and 54 kD, and (b) the cDNA sequence of (BALB/c x B6)F1 is identical to B6. Thus, there appears to be allelic exclusion of 5E6 expression that may be related to the ability of F1 hybrid mice to reject parental H-2d bone marrow cell grafts.
Cell cycle control of c-kit+IL-7R+ B precursor cells by two distinct signals derived from IL-7 receptor and c-kit in a fully defined medium.
Authors: Yasunaga M , Wang F , Kunisada T , Nishikawa S , Nishikawa S
Published: June 2004

An important goal for the investigation of the proliferation of mammalian cells is to establish a fully defined condition for culturing them in vitro. Here, we report establishment of a fully defined culture condition that supports the primary culture of normal c-kit+IL-7 receptor (IL-7R)+ B precursor cells without the aid of stromal cell lines. This defined culture condition contains IL-7, the ligand for c-kit, transferrin, insulin, and bovine serum albumin as protein components. By using the cell lines derived from RAG2(-/-) mice, which do not differentiate into c-kit- stage, we have evaluated the role of each protein in the cell cycle progression of c-kit+IL-7R+ B precursor cells. Since B precursor cells can grow without insulin, c-kit remains a sole functional receptor tyrosine kinase for their growth. While both c-kit ligand (KL) and IL-7 are the requisite molecules for sustained proliferation of B precursor cells, each molecule plays distinct roles. IL-7 starvation results in prompt arrest of the cells at G1. An accumulation of the cells in the mitotic phase was also detected. Thus, the major role of IL-7 is to regulate the G1/S transition and the process of cytokinesis of B precursor cells. Although prolonged KL starvation over 48 h resulted in accumulation of G1 cells, its effect could not be detected within 24 h, which is long enough for all the cells to complete one cell cycle. This suggests that KL might be involved in the cell cycle progression of B precursor cells in a manner that its signal could still be effective in the one or two cell cycles that follow. Although molecular nature of the signals underlying the present observation awaits future investigation, the method described in this report would provide a useful model system for investigating the signaling pathways that are involved in the cell cycle progression of B precursor cells.
Prevention of experimental allergic encephalomyelitis in rats by targeting autoantigen to B cells: evidence that the protective mechanism depends on changes in the cytokine response and migratory properties of the autoantigen-specific T cells.
Authors: Saoudi A , Simmonds S , Huitinga I , Mason D
Published: June 2004

Previous experiments from this laboratory have shown that Lewis rats were protected from experimental allergic encephalomyelitis (EAE) induced by the injection of myelin basic protein (MBP) in Freund's complete adjuvant if they were treated with the encephalitogenic peptide of MBP covalently linked to mouse anti-rat immunoglobulin (Ig) D. It was suggested that this protection developed because the antibody-peptide conjugate targeted the peptide to B cells and that this mode of presentation induced a Th2-like T cell response that controlled the concomitant encephalitogenic Th1 reaction to the autoantigen. The current experiments were carried out to test this hypothesis and to examine the alternative explanation for the protective effect of the conjugate pretreatment, namely that it induced a state of nonresponsiveness in the autoantigenspecific T cells. It was shown that EAE induction was suppressed in Lewis rats when the antibody-peptide conjugate was injected intravenously 14 and 7 d before immunization with MBP in adjuvant, but that anti-MBP antibody titers were at least as high in these animals as in controls that were not pretreated with the conjugate before immunization. Lymph node cells from these pretreated animals, while proliferating in vitro to MBP as vigorously as those from controls, produced less interferon gamma and were very inferior in their ability to transfer disease after this in vitro activation. In contrast, these same lymph node cells from protected rats generated markedly increased levels of messenger RNA for interleukin (IL)-4 and IL-13. When these in vitro experiments were repeated using the encephalitogenic peptide rather than MBP as the stimulus, the proliferative response of lymph node cells from pretreated donors was less than that from controls but was still readily detectable in the majority of experiments. Furthermore, the cytokine expression induced by the peptide was similar to that elicited by whole MBP. While these results support the original hypothesis that the anti-IgD-peptide conjugate pretreatment protected rats from EAE by inducing a Th2-type cytokine response, a totally unexpected finding was that this pretreatment greatly reduced the level of leukocyte infiltration into the central nervous system. This result provides a direct explanation for the protective effect of the pretreatment, but it raises questions regarding migratory and homing patterns of leukocytes activated by different immunological stimuli.
Mechanisms of acquired thymic tolerance in experimental autoimmune encephalomyelitis: thymic dendritic-enriched cells induce specific peripheral T cell unresponsiveness in vivo.
Authors: Khoury S J , Gallon L , Chen W , Betres K , Russell M E , Hancock W W , Carpenter C B , Sayegh M H , Weiner H L
Published: June 2004

Experimental autoimmune encephalomyelitis (EAE), an experimental model for the study of multiple sclerosis, is an autoimmune disease of the central nervous system that can be induced in a number of species by immunization with myelin basic protein (MBP). MBP-reactive CD4+ T cells, predominantly expressing the V beta 8.2 T cell receptor (TCR), migrate from the peripheral lymphoid organs and initiate the inflammatory response in the brain. We have previously shown that a single intrathymic injection of MBP or its major encephalitogenic peptide (p71-90), but not a nonencephalitogenic peptide (p21-40), induces antigen-specific systemic tolerance and inhibits the induction of EAE in Lewis rats. In this study, we investigated the mechanisms of induction and maintenance of acquired thymic tolerance in this model. First, we investigated which thymic cell is responsible for "induction" of systemic tolerance. Thymic dendritic-enriched cells, isolated by plastic adherence, when incubated in vitro with p71-90 and injected intravenously into Lewis rats, were capable of preventing the development of EAE, but his protection was lost in thymectomized recipients. In addition, intravenous injection of thymic dendritic cells isolated from animals that had been previously injected intrathymically with p71-90 but not p21-40 also prevented the development of EAE. Second, to determine the "effector" mechanisms involved in acquired thymic tolerance, we compared TCR expression in the brains of animals with actively induced EAE with TCR expression in animals that received intrathymic injection of p71-90 or p21-40. Using a semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) technique, we found increased expression of CD4 and V beta 8.2 message in brains of immunized animals compared with those of naive animals. In animals intrathymically injected with p71-90 but not p21-40, CD4 and V beta 8.2 transcript levels were significantly reduced compared with immunized controls. Immunohistologic studies of brain tissue and spleens with specific V beta 8.2 and control V beta 10 monoclonal antibodies confirmed these observations in vivo. These findings, taken together with recent data demonstrating that activated T cells circulate through the thymus, suggest that interaction of thymic dendritic cells with specific TCR of activated peripheral T cells can lead to inactivation of these antigen-specific cells and confirm the role of V beta 8.2-expressing T cells in EAE.
Sequential reduction of mitochondrial transmembrane potential and generation of reactive oxygen species in early programmed cell death.
Authors: Zamzami N , Marchetti P , Castedo M , Decaudin D , Macho A , Hirsch T , Susin S A , Petit P X , Mignotte B , Kroemer G
Published: June 2004

Programmed cell death (PCD) is a physiological process commonly defined by alterations in nuclear morphology (apoptosis) and/or characteristic stepwise degradation of chromosomal DNA occurring before cytolysis. However, determined characteristics of PCD such as loss in mitochondrial reductase activity or cytolysis can be induced in enucleated cells, indicating cytoplasmic PCD control. Here we report a sequential disregulation of mitochondrial function that precedes cell shrinkage and nuclear fragmentation. A first cyclosporin A-inhibitable step of ongoing PCD is characterized by a reduction of mitochondrial transmembrane potential, as determined by specific fluorochromes (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine++ + iodide; 3,3'dihexyloxacarbocyanine iodide). Cytofluorometrically purified cells with reduced mitochondrial transmembrane potential are initially incapable of oxidizing hydroethidine (HE) into ethidium. Upon short-term in vitro culture, such cells acquire the capacity of HE oxidation, thus revealing a second step of PCD marked by mitochondrial generation of reactive oxygen species (ROS). This step can be selectively inhibited by rotenone and ruthenium red yet is not affected by cyclosporin A. Finally, cells reduce their volume, a step that is delayed by radical scavengers, indicating the implication of ROS in the apoptotic process. This sequence of alterations accompanying early PCD is found in very different models of apoptosis induction: glucocorticoid-induced death of lymphocytes, activation-induced PCD of T cell hybridomas, and tumor necrosis factor-induced death of U937 cells. Transfection with the antiapoptotic protooncogene Bcl-2 simultaneously inhibits mitochondrial alterations and apoptotic cell death triggered by steroids or ceramide. In vivo injection of fluorochromes such as 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide; 3,3'dihexyloxacarbocyanine iodide; or HE allows for the detection of cells that are programmed for death but still lack nuclear DNA fragmentation. In particular, assessment of mitochondrial ROS generation provides an accurate picture of PCD-mediated lymphocyte depletion. In conclusion, alterations of mitochondrial function constitute an important feature of early PCD.
Growth of donor-derived dendritic cells from the bone marrow of murine liver allograft recipients in response to granulocyte/macrophage colony-stimulating factor.
Authors: Lu L , Rudert W A , Qian S , McCaslin D , Fu F , Rao A S , Trucco M , Fung J J , Starzl T E , Thomson A W
Published: June 2004

Allografts of the liver, which has a comparatively heavy leukocyte content compared with other vascularized organs, are accepted permanently across major histocompatibility complex barriers in many murine strain combinations without immunosuppressive therapy. It has been postulated that this inherent tolerogenicity of the liver may be a consequence of the migration and perpetuation within host lymphoid tissues of potentially tolerogenic donor-derived ("chimeric") leukocytes, in particular, the precursors of chimeric dendritic cells (DC). In this study, we have used granulocyte/macrophage colony-stimulating factor to induce the propagation of progenitors that give rise to DC (CD45+, CD11c+, 33D1+, nonlymphoid dendritic cell 145+, major histocompatibility complex class II+, B7-1+) in liquid cultures of murine bone marrow cells. Using this technique, together with immunocytochemical and molecular methods, we show that, in addition to cells expressing female host (C3H) phenotype (H-2Kk+; I-E+; Y chromosome-), a minor population of male donor (B10)-derived cells (H-2Kb+; I-A+; Y chromosome+) can also be grown in 10-d DC cultures from the bone marrow of liver allograft recipients 14 d after transplant. Highly purified nonlymphoid dendritic cell 145+ DC sorted from these bone marrow-derived cell cultures were shown to comprise approximately 1-10% cells of donor origin (Y chromosome+) by polymerase chain reaction analysis. In addition, sorted DC stimulated naive, recipient strain T lymphocytes in primary mixed leukocyte cultures. Evidence was also obtained for the growth of donor-derived cells from the spleen but not the thymus. In contrast, donor cells could not be propagated from the bone marrow or other lymphoid tissues of nonimmunosuppressed C3H mice rejecting cardiac allografts from the same donor strain (B10). These findings provide a basis for the establishment and perpetuation of cell chimerism after organ transplantation.
Dimerization of soluble major histocompatibility complex-peptide complexes is sufficient for activation of T cell hybridoma and induction of unresponsiveness.
Authors: Abastado J P , Lone Y C , Casrouge A , Boulot G , Kourilsky P
Published: June 2004

Major histocompatibility complex (MHC) class I molecules are cell-surface proteins that present peptides to CD8+ T cells. These peptides are mostly derived from endogenously synthesized protein. Recombinant, soluble MHC class I molecules were produced, purified, and loaded homogeneously with synthetic peptide. These MHC-peptide complexes were used to activate a T cell hybridoma. While monomers of MHC-peptide bound to the T cell, they showed no stimulatory activity. Dimers fully triggered the T cell hybridoma to secrete interleukin 2. This response was followed by a state in which the T cell was refractory to restimulation as a result of defective signal transduction through the T cell receptor.
Inhibition of cartilage and bone destruction in adjuvant arthritis in the rat by a matrix metalloproteinase inhibitor.
Authors: Conway J G , Wakefield J A , Brown R H , Marron B E , Sekut L , Stimpson S A , McElroy A , Menius J A , Jeffreys J J , Clark R L
Published: June 2004

Considerable evidence has associated the expression of matrix metalloproteinases (MMPs) with the degradation of cartilage and bone in chronic conditions such as arthritis. Direct evaluation of MMPs' role in vivo has awaited the development of MMP inhibitors with appropriate pharmacological properties. We have identified butanediamide, N4-hydroxy-2-(2-methylpropyl)-N1-[2-[[2-(morpholinyl)ethyl]-,[S- (R*,S*)] (GI168) as a potent MMP inhibitor with sufficient solubility and stability to permit evaluation in an experimental model of chronic destructive arthritis (adjuvant-induced arthritis) in rats. In this model, pronounced acute and chronic synovial inflammation, distal tibia and metatarsal marrow hyperplasia associated with osteoclasia, severe bone and cartilage destruction, and ectopic new bone growth are well developed by 3 wk after adjuvant injection. Rats were injected with Freund's adjuvant on day 0. GI168 was was administered systemically from days 8 to 21 by osmotic minipumps implanted subcutaneously. GI168 at 6, 12, and 25 mg/kg per d reduced ankle swelling in a dose-related fashion. Radiological and histological ankle joint evaluation on day 22 revealed a profound dose related inhibition of bone and cartilage destruction in treated rats relative to rats receiving vehicle alone. A significant reduction in edema, pannus formation, periosteal new bone growth and the numbers of adherent marrow osteoclasts was also noted. However, no significant decrease in polymorphonuclear and mononuclear leukocyte infiltration of synovium and marrow hematopoietic cellularity was seen. This unique profile of antiarthritic activity indicates that GI168 is osteo- and chondro-protective, and it supports a direct role for MMP in cartilage and bone damage and pannus formation in adjuvant-induced arthritis.
CD28 and CTLA-4 have opposing effects on the response of T cells to stimulation.
Authors: Krummel M F , Allison J P
Published: June 2004

The importance of the B7/CD28/CTLA-4 molecules has been established in studies of antigen-presenting cell-derived B7 and its interaction with the T cell costimulatory molecule CD28. CTLA-4, a T cell surface glycoprotein that is related to CD28, can also interact with B7-1 and B7-2. However, less is known about the function of CTLA-4, which is expressed at highest levels after activation. We have generated an antibody to CTLA-4 to investigate the consequences of engagement of this molecule in a carefully defined system using highly purified T cells. We show here that the presence of low levels of B7-2 on freshly explanted T cells can partially inhibit T cell proliferation, and this inhibition is mediated by interactions with CTLA-4. Cross-linking of CTLA-4 together with the TCR and CD28 strongly inhibits proliferation and IL-2 secretion by T cells. Finally, results show that CD28 and CTLA-4 deliver opposing signals that appear to be integrated by the T cell in determining the response to activation. These data strongly suggest that the outcome of T cell antigen receptor stimulation is regulated by CD28 costimulatory signals, as well as inhibitory signals derived from CTLA-4.
Absence of extraocular muscle pathology in Duchenne's muscular dystrophy: role for calcium homeostasis in extraocular muscle sparing.
Authors: Khurana T S , Prendergast R A , Alameddine H S , Tomé F M , Fardeau M , Arahata K , Sugita H , Kunkel L M
Published: June 2004

Duchenne muscular dystrophy (DMD) is characterized by clinical weakness and progressive necrosis of striated muscle as a consequence of dystrophin deficiency. While all skeletal muscle groups are thought to be affected, enigmatically, the extraocular muscles (EOM) appear clinically unaffected. Here we show that dystrophin deficiency does not result in myonecrosis or pathologically elevated levels of intracellular calcium ([Ca2+]i) in EOM. At variance with a previous report, we find no evidence for dystrophin-related protein/utrophin up-regulation in EOM. In vitro experiments demonstrate that extraocular muscles are inherently more resistant to necrosis caused by pharmacologically elevated [Ca2+]i levels when compared with pectoral musculature. We believe that EOM are spared in DMD because of their intrinsic ability to maintain calcium homeostasis better than other striated muscle groups. Our results indicate that modulating levels of [Ca2+]i in muscle may be of potential therapeutic use in DMD.
Viral interleukin 10 (IL-10), the human herpes virus 4 cellular IL-10 homologue, induces local anergy to allogeneic and syngeneic tumors.
Authors: Suzuki T , Tahara H , Narula S , Moore K W , Robbins P D , Lotze M T
Published: June 2004

After the cloning of murine cytokine synthesis inhibitory factor, it was recognized that a homologous open reading frame was encoded within the Epstein-Barr virus (human herpes virus 4). This viral protein has now been termed viral interleukin 10 (vIL-10) to reflect its protein sequence homology to "cellular" IL-10 (cIL-10, either murine or human IL-10). It is now widely accepted that vIL-10 shares many functions with cIL-10, principally, the ability to enhance survival of newly infected B cells and to diminish the production of IFN-gamma and IL-2 during ongoing immune reactions. The immunomodulatory effect of locally secreted vIL-10 and murine IL-10 (mIL-10) was examined in tumor models using CL8-1 (a BL6 melanoma cell line transfected with the H-2Kb class I gene) in syngeneic animals. Although parental BL6 tumor cells grow in immunocompetent syngeneic hosts, CL8-1 are rejected. To achieve local secretion of vIL-10, we generated vIL-10 retroviral vectors. While nontransduced CL8-1 cells (1 x 10(4)) failed to grow when injected intradermally in C57BL/6 mice, CL8-1 cells (1 x 10(4)) transduced with vIL-10 formed palpable tumors and eventually killed 80% of injected animals. Suppression of tumor rejection was also noted when CL8-1 tumors with or without vIL-10 transfection were admixed with syngeneic vIL-10-transfected fibroblasts and inoculated. Since the in vitro proliferation of the tumor was not altered after transduction with the vIL-10 gene and injection of vIL-10-transduced CL8-1 does not affect the rejection of nontransduced CL8-1 inoculated at a distant site, local vIL-10 secretion appears to suppress the process of immune rejection of the target cells in a dose-dependent manner. Similar results were observed for the H-2b MCA105 sarcoma tumor model in allogeneic BALB/c mice (H-2d). Although all animals that received nontransfected MCA105 rapidly rejected these tumors, MCA105 sarcomas transfected with vIL-10 remained palpable for up to 37 d. The local immunosuppressive effect of gene-delivered vIL-10 could be neutralized by anti-human IL-10 monoclonal antibody or could be reversed by the systemic administration of IL-2 or IL-12. In marked contrast, mIL-10 transfection of CL8-1 significantly suppressed tumor growth and frequently led to the rejection of tumor. Similar results were obtained for the murine tumor cell lines MCA102.(ABSTRACT TRUNCATED AT 400 WORDS)
Role of virion-associated glycosylphosphatidylinositol-linked proteins CD55 and CD59 in complement resistance of cell line-derived and primary isolates of HIV-1.
Authors: Saifuddin M , Parker C J , Peeples M E , Gorny M K , Zolla-Pazner S , Ghassemi M , Rooney I A , Atkinson J P , Spear G T
Published: June 2004

This study investigates whether cell-derived glycosylphosphatidylinositol-linked complement control proteins CD55 and CD59 can be incorporated into HIV-1 virions and contribute to complement resistance. Virus was prepared by transfection of cell lines with pNL4-3, and primary isolates of HIV-1 were derived from patients' PBMCs. Virus was tested for sensitivity to complement-mediated virolysis in the presence of anti-gp160 antibody. Viral preparations from JY33 cells, which lack CD55 and CD59, were highly sensitive to complement. HIV-1 preparations from H9 and U937 cells, which express low levels of CD55 and CD59, had intermediate to high sensitivity while other cell line-derived viruses and primary isolates of HIV-1 were resistant to complement-mediated virolysis. Although the primary isolates were not lysed, they activated complement as measured by binding to a complement receptor positive cell line. While the primary isolates were resistant to lysis in the presence of HIV-specific antibody, antibody to CD59 induced lysis. Likewise, antibody to CD55 and CD59 induced lysis of cell line-derived virus. Western blot analysis of purified virus showed bands corresponding to CD55 and CD59. Phosphatidylinositol-specific phospholipase C treatment of either cell line-derived or primary isolates of HIV-1 increased sensitivity to complement while incubation of sensitive virus with purified CD55 and CD59 increased resistance to complement. These results show that CD55 and CD59 are incorporated into HIV-1 particles and function to protect virions from complement-mediated destruction, and they are the first report of host cell proteins functioning in protection of HIV-1 from immune effector mechanisms.