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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Extracts of specific granules and azurophil granules from human neutrophils were tested for their bactericidal activity against various lipopolysaccharide mutants of Salmonella typhimurium LT-2. Three purified granule populations, one specific and two azurophil, were obtained by isopycnic centrifugation of homogenized neutrophils. Each was extracted with 0.2 M acetate buffer (pH 4), and the extracts were dialyzed against phosphate-buffered saline (pH 7) to remove acetate. These extracts contained >/=84% of the lysozyme, lactoferrin, or myeloperoxidase initially present in the whole granules. The S. typhimurium mutants possessed Ra, Rc, Rd(1), Rd(2), or Re lipopolysaccharide. As the carbohydrate content of the lipopolysaccharide decreased, the bacteria became increasingly more susceptible to the bactericidal activity of all granule extracts. Bactericidal activity of the extracts was in the order: mixed (azurophil + specific) >/= azurophil >> specific. Specific granules were bacteriostatic for S through Rd(2) bacteria. They were bactericidal only for the Re mutant. Both azurophil granule populations were equally bactericidal. Extracts boiled for 30 min retained none of their bactericidal activity for any of the bacteria; however, they remained bacteriostatic for the deep rough (Rd(2), Re) mutants. Bactericidal activity was dependent upon pH, in that mixed and azurophil granule contents killed the smooth parent and Ra mutant best at pH 5, the Rc and Rd(1) mutants to the same degree at pH 5 to 8, and the deep rough mutants (Rd(2) and Re) best at pH 8. Specific granule contents were most bacteriostatic for S through Rd(2) bacteria at pH 5 and killed the Re mutant only at pH 8. Thus, as the S. typhimurium lipopolysaccharide content decreased, the bactericidal pH optimum increased. Killing by all extracts was dependent upon incubation temperature, with almost no bactericidal or bacteriostatic activity observed when bacteria and granule fractions were incubated on ice (2 degrees C) and plated immediately. Intermediate killing was observed at 22 degrees C. If bacteria were incubated with granule extracts at 2 degrees C, washed free of extract, suspended in medium without extract, and reincubated at 37 degrees C, killing was observed. This suggested that a component(s) of the extracts was sticking to the bacteria at 2 degrees C but killing only at 37 degrees C.
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PMID:Bactericidal activity of specific and azurophil granules from human neutrophils: studies with outer-membrane mutants of Salmonella typhimurium LT-2. 2

Lactoferrin (LF), the iron-binding protein present in the specific granules of mature granulocytes has been identified as colony inhibitory factor (CIF) which suppresses granulocyte--macrophage colony stimulating activity (CSA) production by monocytes and macrophages in vitro and rebound granulopoiesis in vivo. Separation of LF and CIF by isoelectric focusing confirmed that the regions of inhibitory activity corresponded in both to a pH of congruent to 6.5. In addition, the purified immunoglobulin fraction of rabbit anti-human LF antiserum, but not rabbit anti-transferrin (TF), inactivated the capacity of LF and CIF to inhibit CSA production, an effect blocked by prior incubation of anti-LF with neutralizing concentrations of LF. Suppression of CSA production correlated with the iron-saturation of LF; APO-LF (depleted of iron) was only active concentrations greater than 10(-7) M, native LF (8% iron saturated) was active at 10(-15) M, and fully iron-saturated LF inhibited at 10(-17) M. Suppression of CSA production occurred within a 1/2-h preincubation period with human blood monocytes but was reversed by bacterial lipopolysaccharide (LPS). This reversal was dependent on the relative concentrations of LF to LPS. Serum TF, a biochemically similar iron-binding protein which is antigenically distinct from LF, was only minimally active at concentrations greater than 10(-6) M. LF did not inhibit exogenously stimulated human granylocyte and macrophage colony-forming cells or erythropoietin-dependent human or murine erythroid colony- or erythroid burst-forming cells. Microgram quantities of LF acted in vivo to inhibit rebound granulopoiesis and CSA production in CD1 and C57Bl/6 mice pretreated with cyclophosphamide. These results strongly implicate LF as a physiological regulator of granulopoiesis.
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PMID:Identification of lactoferrin as the granulocyte-derived inhibitor of colony-stimulating activity production. 30 88

Bordetella pertussis was grown in iron (Fe)-free defined medium to limit the growth of the organism. Doubling times of the Fe-starved organism increased by approximately 1 h, and a 40% reduction in the final extent of growth in Fe-depleted medium was observed. Under these conditions, a hydroxamate siderophore named bordetellin was secreted by B. pertussis. Lactoferrin and transferrin supported growth of B. pertussis even when the protein was sequestered inside dialysis tubing. This suggested that binding of lactoferrin and transferrin to B. pertussis was not essential and that bordetellin production plays a major role in Fe uptake. Solid-phase dot blot assays indicated weak binding of lactoferrin to the cell surface, consistent with previous reports of a lactoferrin receptor. Three new proteins of 97, 77, and 63 kDa were synthesized in response to Fe starvation. Fe-inducible proteins of 103, 72, 24, 21, and 18 kDa were also observed. The synthesis of lipopolysaccharide was also altered by Fe availability.
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PMID:Siderophore production and membrane alterations by Bordetella pertussis in response to iron starvation. 130 10

The ability of Shigella flexneri to interact with lactoferrin (Lf) was examined with a 125I-labeled protein-binding assay. The percent binding of human lactoferrin (HLf) and bovine lactoferrin (BLf) to 45 S. flexneri strains was 19 +/- 3 and 21 +/- 3 (mean +/- standard error of the mean), respectively. 125I-labeled HLf and BLf binding to strain M90T reached an equilibrium within 2 h. Unlabeled HLf and BLf displaced the 125I-HLf-bacteria interaction in a dose-dependent manner. The Lf-bacterium complex was uncoupled by KSCN or urea, but not by NaCl. The interaction was specific, and approximately 4,800 HLf binding sites (affinity constant [Ka], 690 nM) or approximately 5,700 BLf binding sites (Ka, 104 nM) per cell were estimated in strain M90T by a Scatchard plot analysis. The native cell envelope (CE) and outer membrane (OM) did not reveal Lf-binding components in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, after being boiled, the CE and OM preparations showed three distinct horseradish peroxidase-Lf reactive bands of about 39, 22, and 16 kDa. The 39-kDa component was also reactive to a monoclonal antibody specific for porin (PoI) proteins of members of the family Enterobacteriaceae. The Lf-binding protein pattern was similar with BLf or HLf, for Crb+ and Crb- strains. The protein-Lf complex was dissociable by KSCN or urea and was stable after treatment with NaCl. Variation (loss) in the O chain of lipopolysaccharide (LPS) markedly enhanced the Lf-binding capacity in the isogenic rough strain SFL1070-15 compared with its smooth parent strain, SFL1070. These data establish that Lf binds to specific components in the bacterial OM; the heat-modifiable, anti-PoI-reactive, and LPS-associated properties suggested that the Lf-binding proteins are porins in S. flexneri.
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PMID:Lactoferrin-binding proteins in Shigella flexneri. 131 3

Lactoferrin is a 77-kDa iron-binding protein to which a wide variety of divergent biologic functions have been ascribed. It has recently been reported that lactoferrin interacts with bacterial lipopolysaccharide (LPS) in such a fashion as to affect the binding of lactoferrin to myeloid cells. Two other potential interactions of LPS and lactoferrin were explored. Lactoferrin prevents hydroxyl radical formation by binding iron, even at low pH. Lactoferrin inhibited iron-catalyzed formation of hydroxyl radical in the presence of LPS at pH 7.4 and 4.5. Low concentrations of LPS can be used to "prime" neutrophils toward enhanced function, such as formation of stimulated superoxide anion. Lactoferrin inhibited LPS priming of neutrophils if LPS contamination of the protein (provided by commercial suppliers) was first reduced. Inhibition of LPS priming was observed whether apolactoferrin or iron-saturated lactoferrin was used. Similar inhibition of LPS priming was observed when neutrophils were incubated with other serum proteins (e.g., albumin, apotransferrin, or iron-saturated transferrin). These results show that LPS should not be expected to affect the free radical biology of lactoferrin, which is a crucial physiologic function of this protein. However, lactoferrin inhibits LPS priming, and this effect requires consideration in experimental models of inflammation.
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PMID:Interaction of lactoferrin and lipopolysaccharide (LPS): effects on the antioxidant property of lactoferrin and the ability of LPS to prime human neutrophils for enhanced superoxide formation. 133 Dec 50

Mannoprotein fractions of Candida albicans were assayed for their effects on the anticandidal activity of human polymorphonuclear leukocytes (PMNL). One fraction, MP-F2, enhanced PMNL inhibition of candidal growth in vitro as potently as bacterial lipopolysaccharide (LPS), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-8. MP-F2-mediated PMNL activation was manifested on yeast and mycelial forms of the fungus, required the integrity of the mannan, and was due to an increase in the actual number of phagocytic PMNL rather than to a greater ingestion of fungal cells by each individual neutrophil. While not inducing augmented O2 production or degranulation of azurophilic granules, MP-F2 strongly stimulated the release of lactoferrin. Lactoferrin inhibited candidal growth in the absence of PMNL, and anti-lactoferrin antibodies reversed both this inhibition and the PMNL activation by MP-F2, GM-CSF, and LPS. Thus, PMNL may be activated by relevant candidal mannoproteins, and release of lactoferrin may add to other antimicrobial mechanisms of PMNL for the control of candidal infections.
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PMID:Identification of a mannoprotein fraction from Candida albicans that enhances human polymorphonuclear leukocyte (PMNL) functions and stimulates lactoferrin in PMNL inhibition of candidal growth. 140 22

The release of tumour necrosis factor (TNF), lactoferrin (LF) and cathepsin C (CC) into plasma and production of thromboplastin (TPL) in monocytes were studied in lipopolysaccharide (LPS) stimulated heparinized whole blood from 10 healthy donors. The influence of dextran 70, haemaccel and methylprednisolone on levels of these parameters were examined. TNF concentration in plasma 5 min after the addition of LPS (0 h) was 250 pg/ml (median), 520 pg/ml after 1 h and 1300 pg/ml after 3 h. The addition of dextran 70 to the blood in addition to LPS at the same intervals gave significantly higher values of 740 pg/ml and 1800 pg/ml after 1 h and 3 h respectively. Unstimulated cells had no TPL but after 1 h with LPS, the TPL activity in incubated cells was 2.3 mU/10(6) monocytes and after 3 h, 2.7 mU/10(6) monocytes. LPS induced the secretion of LF from granulocytes (PMN) and the levels 5 min after the addition of LPS (0 h) were 2.1 mg/l (control 0.2 mg/l) and after 1 h, 5.3 mg/l (control 1.3 mg/l) in plasma after LPS stimulation. Haemaccel enhanced the LPS-induced generation of TPL in monocytes and production of CC. The LPS-induced secretion of LF was, to a small extent, influenced by the three reagents tested. Methylprednisolone (1 mmol/l) reduced the production and appearance of TNF in plasma and the generation of TPL activity in monocytes. This model for stimulating heparinized whole blood is suitable for examination of the production and appearance of cellular factors and the influence of drugs on this production.
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PMID:The production of tumour necrosis factor, tissue thromboplastin, lactoferrin and cathepsin C during lipopolysaccharide stimulation in whole blood. 169 28

Salmonella serotype Typhimurium is a facultative intracellular pathogen that causes a systemic infection in naturally, or experimentally, infected mice. After oral contamination, Typhimurium colonizes the ileal mucosa and Peyer's patches and invades draining mesenteric lymph nodes. From these primary sites of infection, bacteria dissiminate to the reticuloendothelial system and proliferate rapidly in spleen and liver. Several virulence factors are encoded by chromosomal genes. The ability of Typhimurium to adhere to and invade epithelial cells has been associated with flagella, pili of type I and mannose-resistant haemagglutinating activity. By comparing the virulence of isogenic strains, it appeared that these traits played a marginal role and were not essential for full virulence expression. It is now clear that other surface structures are important for the invasiness capacity of Typhimurium. To multiply in the reticuloendothelial system, a complete lipopolysaccharide is necessary for the bacteria in resisting serum bactericidal activity and producing tissue damage. Salmonella have evolved a specialized iron-binding ligand, termed enterobactin, to acquire iron necessary for their multiplication. Enterobactin competes with the host iron-binding proteins (transferrin or lactoferrin) to secure the iron required by the bacteria. Though the presence of an enterotoxin in Salmonella is still controversial, there is now substantial evidence to support this concept. Recently, a gene encoding an enterotoxin has been cloned from Typhimurium and expressed in E. coli. Typhimurium strains harbour a 90 kilobases (kb) plasmid which is essential for virulence. This plasmid encodes virulence factors required for replication of Salmonella in liver and spleen. It was postulated that the plasmid allowed Typhimurium to multiply in Kupffer cells and in splenic macrophages. The virulence-associated region of the plasmid restored full virulence to plasmidless strains. Transposon insertion mutagenesis demonstrated the existence of two DNA sequences, designated Vir A and Vir B, which are essential for virulence expression. The Vir A region has been sequenced; it encodes four polypeptides with apparent molecular mass of 27,000, 28,000, 33,000 and 70,000. The Vir B region encodes two polypeptides of 38,000 and 43,000. In an attempt to identify bacterial components contributing to invasion of HeLa cells by Salmonella serovar Typhi, we cloned a 30 kb DNA sequence necessary for entry of bacteria into epithelial cells. However, this sequence is not sufficient for conferring an invasive phenotype to E. coli strains. From this DNA fragment, a short segment of 487 bp was subcloned, sequenced and used as probe to detect Salmonella.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Virulence factors of Salmonella: from molecular genetics to diagnostic applications]. 174 21

Escherichia coli H10407 demonstrated low 125I-human lactoferrin (HLf) binding (7%) and was insusceptible to group A (A, E1, E2, E3, E6, and K) and group B (B, D, Ia, Ib, and V) colicins. Conversely, a spontaneous HLf high-binding (44%) variant, H10407(Lf), demonstrated an increase susceptibility to both colicin groups. Colicin-insusceptible E. coli wild-type strains 75ColT, 84ColT, and 981ColT showed a low degree of HLf binding, i.e., 4, 8, and 10%, respectively. The HLf binding capacity was high in the corresponding colicin-susceptible mutants 75ColS (43%), 84ColS (32%), and 981ColS (43%). Furthermore, HLf low- (less than 5%) and high- (greater than 35%) binding E. coli clinical isolates (10 in each category) were tested for susceptibility against 11 colicins. Colicin V susceptibility did not correlate with HLf binding in either categories. However, with the remaining colicins, three distinct HLf-binding, colicin susceptibility patterns were observed; (i) 10 of 10 HLf low-binding strains were colicin insusceptible, (ii) 6 of 10 HLf high-binding strains were also colicin insusceptible, and (iii) the remaining HLf high binders were highly colicin susceptible. Certain proteins in the cell envelope and outer membrane of wild-type H10407 (HLf low binder, colicin insusceptible) showed a lower mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis compared to the corresponding proteins of mutant H10407(Lf) (HLf high binder, colicin susceptible). These mobility differences were also associated with HLf-binding proteins in Western blot (ligand blot) analysis. The wild type showed a smooth form of lipopolysaccharide (LPS) with a distinct ladder of O-chains, compared to the rough LPS of the mutant.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Correlation between human lactoferrin binding and colicin susceptibility in Escherichia coli. 181 Jan 87

We have localized several major extracellular matrix protein receptors in the specific granules of human polymorphonuclear (PMN) and monocytic leukocytes using double label immunoelectron microscopy (IEM) with ultrathin frozen sections and colloidal-gold conjugates. Rabbit antibodies to 67-kD human laminin receptor (LNR) were located on the inner surface of the specific granule membrane and within its internal matrix. LNR antigens co-distributed with lactoferrin, a marker of specific granules, but did not co-localize with elastase in azurophilic granules of PMNs. Further, CD11b/CD18 (leukocyte receptor for C3bi, fibrinogen, endothelial cells, and endotoxin), mammalian fibronectin receptor (FNR), and vitronectin receptor (VNR) antigens were also co-localized with LNR in PMN specific granules. A similar type of granule was found in monocytes which stained for LNR, FNR, VNR, CD18, and lysozyme. Activation of PMNs with either PMA, f-met-leu-phe (fMLP), tumor necrosis factor (TNF), or monocytic leukocytes with lipopolysaccharide (LPS), induced fusion of specific granules with the cell membrane and expression of both LNR and CD18 antigens on the outer cell surface. Further, stimulation led to augmented PMN adhesion on LN substrata, and six- to eightfold increases in specific binding of soluble LN that was inhibited by LNR antibody. These results indicate that four types of extracellular matrix receptors are located in leukocyte specific granules, and suggest that up-regulation of these receptors during inflammation may mediate leukocyte adhesion and extravasation. We have thus termed leukocyte specific granules adhesomes.
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PMID:Adhesomes: specific granules containing receptors for laminin, C3bi/fibrinogen, fibronectin, and vitronectin in human polymorphonuclear leukocytes and monocytes. 248 Mar 53


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