UMLS:C0021051 - FACTA Search

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Query: UMLS:C0021051 (immunodeficiency)
71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present study we investigated to what extent the peripheral carbohydrate structure of N-linked glycans influences the antigenic properties of human immunodeficiency virus type 1 glycoprotein 120 (gp120). Recombinant gp120 was purified from GMK cells infected with a recombinant vaccinia virus expressing gp120. Purified gp120 was then coated onto 96-well ELISA microplates and subjected to sequential removal of peripheral monosaccharide units. Modified or unmodified gp120 was then incubated with monoclonal antibodies recognizing specific epitopes of gp120 and with a reporter lectin to determine the extent of carbohydrate elimination. Antibody and lectin binding was quantified in an enzyme-linked system. We found that the carbohydrate structure NeuAc-Gal beta (1-4) of N-linked glycans, defined both by lectin reactivity and by specific glycosidases, is involved in modulating the binding of antibody to a number of epitopes of peptide nature. The binding of antibody to one class of epitopes, situated in a region between amino acids 200 and 230, was strongly increased by removal of NeuAc-Gal beta (1-4), whereas the binding to epitopes in the V3 region was decreased and the binding to epitopes in the far N-terminal region was not altered by the treatment. These results suggested that peripheral structures of N-glycans are involved in modulating the overall conformation of gp120.
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PMID:Carbohydrate determinant NeuAc-Gal beta (1-4) of N-linked glycans modulates the antigenic activity of human immunodeficiency virus type 1 glycoprotein gp120. 128 69

A cDNA encoding UDP-GlcNAc:Gal beta 1-3GalNAc-R (GlcNAc to GalNAc) beta 1-6GlcNAc transferase (EC 2.4.1.102), which forms critical branches in O-glycans, has been isolated by an expression cloning approach using Chinese hamster ovary (CHO) cells. Increased activity of this enzyme and the concomitant occurrence of the O-glycan core 2 structure [Gal beta 1-3(GlcNAc beta 1-6)GalNAc] has been observed in a variety of biological processes, such as T-cell activation and immunodeficiency due to the Wiskott-Aldrich syndrome and AIDS. Since CHO cells do not express this enzyme, CHO cell lines were established to stably express polyoma large tumor (T) antigen, which enables transient expression cloning. Because the antibody used was found to detect most efficiently the oligosaccharide products attached to leukosialin, the CHO cells were also stably transfected with leukosialin cDNA. By using this particular CHO cell line, a cDNA that encodes a protein determining the formation of the core 2 structure was isolated from an HL-60 cDNA library. The cDNA sequence predicts a protein with type II membrane topology, as has been found for all other mammalian glycosyltransferases cloned to date. The expression of the presumed catalytic domain as a fusion protein with the IgG binding domain of protein A enabled us to demonstrate unequivocally that the cDNA encodes the core 2 beta-1,6-N-acetylglucosaminyltransferase, the enzyme responsible for the formation of Gal beta 1-3(GlcNAc beta 1-6)GalNAc structures. No activity with this enzyme was detected toward the acceptors for other beta 1-6GlcNAc transferases.
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PMID:Expression cloning of a cDNA encoding UDP-GlcNAc:Gal beta 1-3-GalNAc-R (GlcNAc to GalNAc) beta 1-6GlcNAc transferase by gene transfer into CHO cells expressing polyoma large tumor antigen. 132 93

A series of four mannose(Man)-, three N-acetylglucosamine (GlcNAc)n-, ten N-acetylgalactosamine/galactose(GalNAc/Gal)-, one 5-acetylneuraminic acid (alpha-2,3-Gal/GalNAc)- and one 5-acetylneuroaminic acid(alpha-2,6-Gal/Gal-NAc)-specific plant agglutinins were evaluated for their antiviral activity in vitro. the mannose-specific lectins from the orchid species Cymbidium hybrid (CA), Epipactis helleborine (EHA) and Listera ovata (LOA) were highly inhibitory to human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) in MT-4, and showed a marked anti-human cytomegalovirus (CMV), respiratory syncytial virus (RSV) and influenza A virus activity in HEL, HeLa and MDCK cells, respectively. The 50% effective concentration (EC50) of CA and EHA for HIV ranged from 0.04 to 0.08 micrograms/ml, that is about 3 orders of magnitude below their toxicity threshold (50% inhibitory concentration for MT-4 cell growth: 54 to 60 micrograms/ml). Also, the (GlcNAc)n-specific lectin from Urtica dioica (UDA) was inhibitory to HIV-1-, HIV-2-, CMV-, RSV- and influenza A virus-induced cytopathicity at an EC50 ranging from 0.3 to 9 micrograms/ml. The GalNAc/Gal-, alpha-2,3-Gal/GalNAc- or alpha-2,6-Gal/GalNAc-specific lectins were not inhibitory to HIV or CMV at non-toxic concentrations. CA, EHA and UDA proved to be potent inhibitors of syncytium formation between persistently HIV-1- and HIV-2-infected HUT-78 cells and CD4+ Molt/4 (clone 8) cells (EC50: 0.2-2 micrograms/ml). Unlike dextran sulfate, the plant lectins CA, EHA and UDA did not interfere with HIV-1 adsorption to MT-4 cells and RSV- and influenza A virus adsorption to HeLa and MDCK cells, respectively. They presumably interact at the level of virion fusion with the target cell.
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PMID:The mannose-specific plant lectins from Cymbidium hybrid and Epipactis helleborine and the (N-acetylglucosamine)n-specific plant lectin from Urtica dioica are potent and selective inhibitors of human immunodeficiency virus and cytomegalovirus replication in vitro. 132 50

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive immunodeficiency affecting B lymphocytes, T lymphocytes, and platelets. Previous studies on lymphocytes from WAS patients have revealed that leu-kosialin (CD43), a cell-surface glycoprotein bearing approximately 90 O-linked oligosaccharide chains, shows an aberrant electrophoretic mobility. To determine whether this finding reflects a different pattern of O-linked glycosylation in WAS cells, we have compared healthy individuals and WAS patients with respect to glycosyltransferase activities in T lymphocytes, platelets, and Epstein-Barr virus (EBV)-immortalized B cell lines. Stimulation of peripheral T cells from normal individuals in vitro with anti-CD3 antibodies and interleukin-2 was associated with a 3-fold increase in UDP-GlcNAc:Gal beta 3GalNAc-R (GlcNAc to GalNAc) beta 6-N-acetylglucosaminyltransferase (core 2 GlcNAc-T) from 0.8 to 2.2 nmol/mg/h. In contrast, peripheral T lymphocytes from WAS patients showed an inversion of this phenotype with high core 2 GlcNAc-T activity in unstimulated cells (2.3 nmol/mg/h) and a 2-3-fold decrease in activity following stimulation. Core 2 GlcNAc-T activity was also three times higher in platelets from WAS patients than in normal platelets. Glycosyltransferase activities were measured in immortalized B cell lines established from WAS and normal subjects by infection with EBV. Core 2 GlcNAc-T was less than 0.4 nmol/mg/h in WAS EBV-B cell lines compared to 2.4 nmol/mg/h in EBV-B cell lines from healthy individuals, In contrast, CMP-SA:SA alpha 2-3Gal beta 1-3GalNAc-R (where SA represents sialyl (sialic acid to GalNAc) alpha 6-sialyltransferase II activity was 2.0 nmol/mg/h in the WAS EBV-B cell and less than .01 nmol/mg/h in EBV-B cell lines derived from normal subjects. Eleven other glycosyltransferase activities were measured and found to be similar in EBV-B cell lines from WAS and normal individuals. Polylactosamine sequences were much reduced in the O-linked oligosaccharides of CD43 from WAS EBV-B cells consistent with decreased core 2 GlcNAc-T activity and expression of core 1 oligosaccharides in the cells. In conclusion, B cells, T cells, and platelets in WAS patients show abnormal expression of two developmentally regulated glycosyltransferases, consistent with the idea that the WAS immunodeficiency is due to a failure of normal lymphocyte maturation.
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PMID:Aberrant O-linked oligosaccharide biosynthesis in lymphocytes and platelets from patients with the Wiskott-Aldrich syndrome. 200 80

The Wiskott-Aldrich syndrome (WAS) is an X-linked immune deficiency disorder characterized clinically by both lymphocyte and platelet dysfunction. Studies of WAS T lymphocytes have revealed deficient or defective cell surface expression of the highly O-glycosylated leucocyte sialoglycoprotein CD43. To further elucidate the basis for, and functional relevance of, CD43 modifications on WAS lymphocytes, we have studied lymphocytes from two WAS patients with regard to membrane glycoprotein profile and mitogen-induced proliferative responses. CD43 was found to be either absent or altered in size on peripheral blood lymphocytes and lectin-stimulated T cells from both patients. Compared with control cells, the WAS lymphocytes displayed reduced, but measurable proliferative responses to lectins and neuraminidase/galactose oxidase, and virtually no response to periodate, a mitogenic agent which targets sialic acid residues on membrane glycoproteins such as CD43. Analysis of activities of three glycosyltransferases involved in O-glycosylation revealed marked reduction in the level of activity of UDP-N-acetylglucosamine: Gal beta 1-3GalNAc-R beta-1,6-N-acetylglucosamine (beta-1,6-GlcNAc) transferase in one WAS patient and no detectable activity of this enzyme in a second. beta-1,6-GlcNAc transferase activity has recently been shown to increase during T cell activation coincident with changes in the O-linked glycans on CD43. A selective reduction of this glycosyltransferase in WAS lymphocytes suggests that O-linked oligosaccharides may be important to the structure of membrane glycoproteins involved in lymphocyte activation.
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PMID:Altered expression of leucocyte sialoglycoprotein in Wiskott-Aldrich syndrome is associated with a specific defect in O-glycosylation. 280 29

A new natural anti-alpha-galactosyl IgG antibody (anti-Gal) was found to be present in high titer in the serum of every normal individual studied. The antibody was isolated by affinity chromatography on a melibiose-Sepharose column. The reactivity of the antibody was assessed by its interaction with alpha-galactosyl residues on rabbit erythrocytes (RabRBC). The specificity was determined by inhibition experiments with various carbohydrates. The anti-Gal interacts with alpha-galactosyl residues, possibly on glycolipids of human RBC (HuRBC), after removal of membrane proteins by treatment with pronase. In addition, the anti-Gal bind specifically to normal and pathologically senescent HuRBC, suggesting a physiological role for this natural antibody in the aging of RBC. The ubiquitous presence of anti-Gal in high titers throughout life implies a constant antigenic stimulation. In addition to the theoretical interest in the antibody, the study of the anti-Gal reactivity seems to bear immunodiagnostic significance. Decrease in the antibody titer was found to reflect humoral immunodeficiency disorders.
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PMID:A unique natural human IgG antibody with anti-alpha-galactosyl specificity. 649 3

DNA coding for bacteriophage T7 RNA polymerase (T7-RNAP) was inserted into a positive selection-vector form of the T4 genome, placing it under the control of bacteriophage T4 ipIII promoters. The recombinant T4::T7-RNAP fusion phage retained infectivity and produced T7-RNAP in infected cells. Fusion genes were constructed by insertion into a plasmid containing an iPIII (encoding internal protein III) target portion and a bacteriophage T7 promoter region. When Escherichia coli cells containing the plasmid were infected with the T4::T7-RNAP re-phage, the bacteria produced fusion protein at high levels. The newly synthesized T4::T7-RNAP re-phage progeny package and process the fusion protein into the phage capsid during head morphogenesis. In this paper, we demonstrate that truncated T4 internal protein IPIII, human IPIII::beta Glo (beta-globin) fusion protein, E. coli IPIII::beta Glo::beta Gal (beta-galactosidase) triple-fusion protein and IPIII::V3 fusion protein (human immunodeficiency virus envelope protein gp120 V3 region) are expressed at high levels by T4::T7-RNAP induction. With IPIII::beta Glo, expression-packaging-processing (EPP) occurs simultaneously with T4::T7-RNAP re-phage infection. We also demonstrate that T4::T7-RNAP re-phage stabilize unstable proteins such as the X90 fragment of beta Gal, thought to be degraded by the lon protease. An unstable 20-kDa fragment of the large subunit of human cytochrome b558, an integral membrane protein in phagocytes, is subject to proteolytic degradation even when produced in the lon-deficient BL21 strain. However, upon induction with T4::T7-RNAP re-phage, the 20-kDa protein is produced intact.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Protection from proteolysis using a T4::T7-RNAP phage expression-packaging-processing system. 755 16

Immunodeficiency caused by HIV infection probably results from profound dysregulation of normal T lymphocyte properties by the virus. Despite description of the virus cytopathicity and numerous modifications in T cell functions, such as perturbation of antigen receptor signaling, CD4 downregulation, and induction of apoptosis, the precise mechanisms underlying the disruption of normal immune responses have not yet been elucidated. In the present study, we show that HIV-1-infected lymphocytes of the CEM cell line (either latent or virus-producing) and HIV-1-infected CD4+ lymphocytes have several membrane proteins with altered glycosylation patterns. Using lectins with specificity for different carbohydrate moieties, we could demonstrate the presence of two exposed nonsialylated disaccharides: a terminal Gal beta 1-->3GalNAc and a terminal Gal beta 1-->4GlcNAc. In particular, CD45, one of the major T cell glycoproteins, appeared to be partially sialylated on N- and O-linked carbohydrate moieties. Concerning the latter, PNA lectin which recognizes nonsialylated terminal Gal beta 1-->3GalNAc might precipitate up to 75% of the total tyrosine phosphatase activity displayed by CD45 molecules from one latently HIV-1-infected CEM cell line. Since CD45 glycoproteins are thought to play an important regulatory role in cell-to-cell interactions owing to their variable extracellular region and because they may regulate membrane signaling through their intracellular phosphatase domains, we suggest that these altered CD45 molecules may present an abnormal signal for natural ligands such as the B-cell-specific surface receptor CD22, thus perturbing the normal immune response in HIV-1-infected individuals.
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PMID:Altered sialylation of CD45 in HIV-1-infected T lymphocytes. 812 60

The primary receptor for the human immunodeficiency virus (HIV) is the CD4 molecule. However, a large body of evidence has demonstrated that some cells that do not express the CD4 receptor can be infected by HIV-1 and HIV-2, indicating that an alternative mechanism of infection must exist for some cell types. Recently it was reported that antibodies against the glycosphingolipid, galactosylceramide (Gal beta 1-1'Cer;GalCer), blocked infection of several CD4 negative cell lines derived from the brain and colon. The hypothesis that GalCer might be involved in the process of HIV entry into these cells was further supported by the finding that recombinant gp120 bound GalCer with high affinity in a high performance thin layer chromatography (HPTLC) binding assay. We have examined the interactions between GalCer and gp120, and found that the oligosaccharides that constitute a large proportion of the molecular mass of this glycoprotein are not involved in binding to this glycolipid. Furthermore, using a panel of monoclonal and monospecific antibodies we have determined that gp120 binds GalCer, and the related molecule 3' sulfo galactosylceramide (sulfatide), at a site that is conformationally close to the its principal neutralizing domain (V3 loop) or at the V3 loop itself.
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PMID:Binding of human immunodeficiency virus type I (HIV-1) gp120 to galactosylceramide (GalCer): relationship to the V3 loop. 818 33

The N-terminal 48 amino acids of the Tat protein of human immunodeficiency virus type (HIV)-1 constitute its activation region. This region can autonomously activate transcription when targeted to the HIV-1 long terminal repeat or certain heterologous promoters either through DNA binding sites located upstream of the transcription initiation site or via downstream RNA binding sites in mammalian cells. To determine whether the Tat activation region can function in yeast, we have assayed the effect of a chimeric gene (GAL-Tat48) expressing the DNA binding domain of the yeast transcription factor Gal4 (residues 1-147) and the activation region of Tat on GAL1 promoter-directed expression of the lacZ reporter gene in Saccharomyces cerevisiae. Our results indicate that the Gal-Tat48 fusion protein can induce significant activation of the GAL1 promoter. Analysis of a number of Tat mutants located within the activation region indicate that the amino acid residues of Tat essential for trans-activation in mammalian cells are also required for transactivation in yeast. Our results suggest that Tat-mediated transcriptional activation may involve a mechanism conserved among yeast and mammalian cells.
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PMID:The activation region of the Tat protein of human immunodeficiency virus type-1 functions in yeast. 819 Jun 42

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