Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026918 (Mycobacterium)
 52,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cytolytic potential of a total number of 118 CD4+ human T cell clones specific for purified protein derivative (PPD) from Mycobacterium tuberculosis, tetanus toxoid, Lolium perenne group I allergen (Lol p I), Poa pratensis group IX allergen (Poa p IX), or Toxocara canis excretory/secretory antigen(s) (TES) was assessed by both a lectin (PHA)-dependent and a MHC-restricted lytic assay and compared with their profile of cytokine secretion. The majority of clones with Th1 or Th0 cytokine profile exhibited cytolytic activity in both assays, whereas Th2 clones usually did not. There was an association between the cytolytic potential of T cell clones and their ability to produce IFN-gamma, even though IFN-gamma produced by T cell clones was not responsible for their cytolytic activity. IL-4 added in bulk culture before cloning inhibited not only the differentiation of PPD-specific T cells into Th1-like cell lines and clones, but also the development of their cytolytic potential. The depressive effect of IL-4 on the development of PPD-specific T cell lines with both Th1 cytokine profile and cytolytic potential was dependent on early addition of IL-4 in bulk cultures. In contrast, the addition in bulk culture of IFN-gamma enhanced both the cytolytic activity of PPD-specific T cell lines, as well as the proportion of PPD-specific T cell clones with cytolytic activity. The addition in bulk cultures before cloning of IFN-gamma or IFN-alpha favored the development of TES-specific and Poa p IX-specific T cells into T cell clones showing a Th0 or even a Th1, rather than a Th2, cytokine profile. Accordingly, most of TES- and Poa p IX-specific T cell clones derived from cultures containing IFN-gamma or IFN-alpha displayed strong cytolytic activity. These data indicate that the majority of human T cell clones that produce IFN-gamma, but not IL-4 (Th1-like), as well as of T cell clones that produce IFN-gamma in combination with IL-4 (Th0-like) are cytolytic. More importantly, they demonstrate that the addition of IFN (alpha and gamma) or IL-4 in bulk cultures before cloning may influence not only the cytokine profile of human CD4+ T cell clones but also their cytolytic potential.
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PMID:IL-4 and IFN (alpha and gamma) exert opposite regulatory effects on the development of cytolytic potential by Th1 or Th2 human T cell clones. 140 25

Tuberculin purified protein derivative (PPD) is a very potent T-cell reactive material in tuberculin-positive individuals, but the components responsible for this reactivity have not been adequately defined. Three purified mycobacterial proteins (MPB70, the BCG 65-kDa protein, and BCG antigen 85B) with different degrees of temperature sensitivity were iodine-labelled and added to BCG culture fluid, and the mixtures were autoclaved at 120 degrees C for 30 min to simulate the initial heating procedure used to prepare PPD. SDS-PAGE followed by protein staining and autoradiography showed that the banded pattern of unheated culture fluid was completely lost after heating, and only the labelled MPB70 preparation retained most of the radioactivity in a fraction with soluble protein of the same size. Most mycobacterial proteins are extensively denatured by these procedures, which explains the previous extensive difficulties in isolating defined constituents from PPD to characterize their behaviour in B- and T-cell reactions. In assays for the carrier effect of NIP-PPD for induction of anti-NIP production in BCG-vaccinated mice, the active fractions were heterogeneous in lectin reactivity as well as in SDS-PAGE. It appears most likely that a number of Mycobacterium tuberculosis proteins give rise to core peptides which resist proteolysis and heat denaturation to possess powerful T-cell-activating ability.
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PMID:Carrier effect of concanavalin A-reactive and -non-reactive material in tuberculin PPD. 240 95

In Mycobacterium tuberculosis culture filtrates, three concanavalin A (ConA)-binding bands of 55, 50 and 38 kilodaltons (kD) were identified by labelling blotted proteins with a ConA-peroxidase conjugate. Binding was inhibited by the competitor sugar alpha-methyl mannoside and by reduction with sodium m-periodate. Bands of 55, 50 and 38 kD stained with Coomasie blue were sensitive to digestion with proteases, thus indicating that they are proteins. Glycoproteins were isolated by lectin affinity chromatography or by elution from nitrocellulose membranes. On the isolated form, the 55-50 kD doublet glycoprotein was 65.4% protein and 34.6% sugar. The purified 38 kD molecule was 74.3% protein and 25.7% carbohydrate. By immunoblot, antibodies against mycobacterial glycoproteins were demonstrated in immunized rabbits and in patients with pulmonary tuberculosis, but not in healthy individuals. Treatment with sodium m-periodate abolished binding of rabbit antibodies to the 38 kD glycoprotein. Reactivity of the 55-50 kD doublet glycoprotein was not altered by reduction. By immunoblot with monoclonal antibodies TB71 and TB72, a carbohydrate-dependent and a carbohydrate-independent epitope could be identified on the 38 kD glycoprotein.
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PMID:Identification, isolation and partial characterization of Mycobacterium tuberculosis glycoprotein antigens. 247 23

Specific stimulation of T cells by phytohemagglutinin and Lens culinaris lectin was inhibited by a soluble factor(s) secreted by normal adherent cells stimulated with culture filtrate protein extract (CFPE) derived from bacterial cultures of Mycobacterium tuberculosis H37Ra (avirulent) and H37Rv (virulent). The induction of the inhibitory factor was blocked by the presence of hyperimmune antisera to H37Rv or H37Ra CFPE. The inhibitory factor did not seem to be a CFPE reprocessed by the adherent cells. Inhibitory activity was maximal in supernatants of adherent-cell cultures incubated for 48 h; the inhibitory factor was heat labile, and its production was dependent on the concentration of M. tuberculosis CFPE. A mouse monocyte-macrophage cell line, ATCC J774A.1, produced an identical inhibitory factor, thus excluding a non-macrophage-contaminating adherent cell as the source of the factor. This inhibitory factor also interfered with the recognition of phytohemagglutinin and Lens culinaris lectin by T cells.
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PMID:Inhibition of mitogenesis induced by phytohemagglutinin and Lens culinaris lectin in adherent-cell supernatants treated with protein extract of Mycobacterium tuberculosis. 308 60

Antigen 60 (A60) is the main thermostable immunogen of both 'old tuberculin' (OT) and 'purified protein derivative' (PPD), known reagents for cutaneous tests in tuberculosis. It is recognized by bidimensional immunoelectrophoresis with anti-BCG antiserum, where it appears as the less mobile component. A60 was prepared from the cytoplasm of Mycobacterium bovis BCG, and purified by exclusion gel chromatography and lectin affinity chromatography. Labelled A60 was obtained by radioiodination and used for a radioimmunoassay. Composition of A60 was explored by use of organic solvents, chemicals and enzymes. It contained two fractions of free and bound lipids, as well as protein and polysaccharide moieties. After removal of both free and bound lipid fractions, the core still retained the ability to form immunoprecipitinogen lines with anti-BCG antiserum. The lipopolysaccharide and lipo-protein moieties of A60, as well as the free lipid fraction, were also complexed by antibodies. It is concluded that A60 is a lipopolysaccharide-protein complex of 10(6) to 10(7) daltons, which is a major immunogenic component of mycobacterial cytoplasm. The detailed structure of this antigen, its immunological properties, and its use for an ELISA type immunoassay for tuberculosis are described in two other publications.
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PMID:Preparation and properties of antigen 60 from Mycobacterium bovis BCG. 354 72

A component of Mycobacterium bovis BCG referred to as BCG-a was isolated through the combined use of monoclonal antibody directed to BCG and affinity chromatography. Analysis of BCG-a by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single prominent band with a molecular weight of ca. 10,000. Structural characterization of BCG-a consisting of amino acid composition and amino-terminal sequence determination was carried out. The intact BCG-a antigen was bound by neither the lectin from common lentils nor concanavalin A, implying that BCG-a does not carry any asparagine-linked oligosaccharides. Immunoprecipitation of 125I-labeled BCG-a with polyclonal and monoclonal antibodies directed against BCG resulted in bands having the same mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as did free 125I-BCG-a. In radioimmunoassays 125I-BCG-a was bound by the monoclonal antibody and by polyclonal antibodies from rabbits that had been immunized to BCG and to Mycobacterium tuberculosis H37Rv. Antibodies to nontuberculous and to nonacid-fast bacteria bound BCG-a poorly or not at all. The binding of 125I-BCG-a by the monoclonal antibody was readily inhibited by extracts of BCG and H37Rv, but it was not as readily inhibited by extracts of nontuberculous mycobacteria and was not at all inhibited by extracts of nonacid-fast bacteria. Considerable inhibition was similarly observed by surface antigens of nonviable, intact BCG organisms. Delayed cutaneous hypersensitivity reactions to small concentrations of BCG-a were elicited in guinea pigs that had been immunized with BCG or H37Rv antigens, but such reactions were not elicited in unimmunized animals.
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PMID:Immunological evaluation of a component isolated from Mycobacterium bovis BCG with a monoclonal antibody to M. bovis BCG. 638 46

The occurrence of glycosylated proteins in Mycobacterium tuberculosis has been widely reported. However, unequivocal proof for the presence of true glycosylated amino acids within these proteins has not been demonstrated, and such evidence is essential because of the predominance of soluble lipoglycans and glycolipids in all mycobacterial extracts. We have confirmed the presence of several putative glycoproteins in subcellular fractions of M. tuberculosis by reaction with the lectin concanavalin A. One such product, with a molecular mass of 45 kDa, was purified from the culture filtrate. Compositional analysis demonstrated that the protein was rich in proline and that mannose, galactose, glucose, and arabinose together represented about 4% of the total mass. The 45-kDa glycoprotein was subjected to proteolytic digestion with either the Asp-N or the Glu-C endopeptidase or subtilisin, peptides were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and glycopeptides were identified by reaction with concanavalin A. Peptides were further separated, and when they were analyzed by liquid chromatography-electrospray mass spectrometry for neutral losses of hexoses (162 mass units), four peptides were identified, indicating that these were glycosylated with hexose residues. One peptide, with an average molecular mass of 1,516 atomic mass units (AMU), exhibited a loss of two hexose units. The N-terminal sequence of the 1,516-AMU glycopeptide was determined to be DPEPAPPVP, which was identical to the sequence of the amino terminus of the mature protein, DPEPAP PVPXTA. Furthermore, analysis of the glycopeptide by secondary ion mass spectrometry demonstrated that the complete sequence of the glycopeptide was DPEPAPPVPTTA. From this, it was determined that the 10th amino acid, threonine, was O-glycosidically linked to a disaccharide composed of two hexose residues, probably mannose. This report establishes that true, O-glycosylated proteins exist in mycobacteria.
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PMID:Evidence for glycosylation sites on the 45-kilodalton glycoprotein of Mycobacterium tuberculosis. 762 4

Pathogenic Mycobacteria colonize host macrophages. Attachment of these organisms to macrophages is the preliminary step prior to invasion of the macrophages by the bacteria. Western blot confirmed that walls of Mycobacterium avium and Mycobacterium tuberculosis contain molecules which are immunologically related to mycotin, a lectin found in Mycobacterium smegmatis. We have demonstrated that the adherence of Mycobacteria to macrophages is significantly inhibited by anti-mycotin antibody or the mycotin-specific sugar, mannan. These observations suggest that prevention of the interaction of mycotin-related molecules on the surfaces of Mycobacteria with mannose-specific receptors on macrophages, offers an important approach for blocking attachment of pathogenic Mycobacteria to macrophages, thereby preventing infection.
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PMID:Mycotin: a lectin involved in the adherence of Mycobacteria to macrophages. 798 97

Mac-2, a 30-35-kDa galactose-binding protein, is synthesized at similar levels in murine peritoneal exudate macrophages whether recruited in response to an intraperitoneal pathogen Mycobacterium microti, to sterile inflammatory stimuli such as thioglycollate broth, or to concanavalin A. In elicited or activated macrophages up to 30% of Mac-2 is constitutively secreted, and secretion is stimulated markedly by calcium ionophore A23187. Only thioglycollate-elicited macrophages express cell surface Mac-2, and binding is mostly (> 80%) a result of affinity for cell surface carbohydrate structures. Mac-2 surface expression is markedly reduced upon further activation of thioglycollate-elicited macrophages with bacterial lipopolysaccharide in vitro. Polylactosamine structures are present on all macrophage populations examined as determined by binding of Lycopersicon esculentum lectin, whereas alpha-galactosyl residues detected by Griffonia simplicifolia isolectin B4 are expressed only on the thioglycollate-elicited macrophages, indicating that these residues are the major determinants responsible for Mac-2 surface expression. Chemical cross-linking experiments have identified binding of endogenous cell-surface Mac-2 to three glycoproteins of molecular masses of 92, 125, and 180 kDa containing alpha-galactosyl and polylactosamine structures on thioglycollate-elicited macrophages. The restricted cell surface distribution of Mac-2 on thioglycollate-elicited peritoneal macrophages, a population of recently recruited monocytes, suggests a role(s) in early events of macrophage infiltration and tissue fixation such as extravasion and cell-matrix interactions.
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PMID:Regulation of secretion and surface expression of Mac-2, a galactoside-binding protein of macrophages. 830 13

Protein glycosylation has an important influence on a broad range of molecular interactions in eukaryotes, but is comparatively rare in bacteria. Several antigens from Mycobacterium tuberculosis, the causative agent of human tuberculosis, have been identified as glycoproteins on the basis of lectin binding, or by detailed structural analysis. By production of a set of alkaline phosphatase (PhoA) hybrid proteins in a mycobacterial expression system, the peptide region required for glycosylation of the 19 kDa lipoprotein antigen from M.tuberculosis was defined. Mutagenesis of two threonine clusters within this region abolished lectin binding by PhoA hybrids and by the 19 kDa protein itself. Substitution of the threonine residues also resulted in generation of a series of smaller forms of the protein as a result of proteolysis. In a working model to account for these observations, we propose that the role of glycosylation is to regulate cleavage of a proteolytically sensitive linker region close to the acylated N-terminus of the protein.
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PMID:Bacterial glycoproteins: a link between glycosylation and proteolytic cleavage of a 19 kDa antigen from Mycobacterium tuberculosis. 867 Aug 58


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