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L Brade

Publications and source records attributed to L Brade.

At least 55 records · Page 3Linked to original sources
PubMed1997

Structural requirements of synthetic oligosaccharides to bind monoclonal antibodies against Chlamydia lipopolysaccharide.

Monoclonal antibodies were generated against a synthetic glycoconjugate containing the trisaccharide alpha-Kdo-(2-->8)-alpha-Kdo-(2-->4)-alpha-Kdo (Kdo, 3-deoxy-D-manno-2-octulopyranosonic acid) which represents the genus-specific epitope of the lipopolysaccharide from the obligatory intracellular human pathogen Chlamydia. Antibodies of all immunoglobulin G isotypes were obtained and characterized by enzyme immunobinding and inhibition assays using the immunizing antigen as well as chemically synthesized derivatives of the Kdo trisaccharide. The latter contained (1) one of the three residues in beta- instead of alpha-linkage, (2) a Kdo residue the carboxyl group of which had been reduced to a CH2OH group (Kdo(C1-red)), or (3) changing the linkage of the terminal Kdo from 2-->8 to 2-->4. Only one compound, namely, alpha-Kdo-(2-->8)-alpha-Kdo(C1-red)-(2-->4)-alpha-Kdo exhibited binding to and inhibition of Kdo trisaccharide-specific antibodies, whereas all other compounds were not active. Structural and conformational investigations using NMR spectroscopy at high field on the allyl glycosides of the oligosaccharides 6-12 confirmed the conformational similarities between those structures 4, 5, and 10 which were able to bind to the antibodies investigated.

Animals↗
PubMed1997

Characterization of serum antibody response to chlamydiae in patients with sexually acquired reactive arthritis.

Sera from patients with sexually acquired reactive arthritis (SARA) with antibodies reacting with C. trachomatis and C. pneumoniae (group 1; n = 20) and also with C. psittaci (group 2; n = 19) were analyzed for antibody specificity. Sera from group 2 reacted significantly more often with C. trachomatis serotype E, H and K and had higher antibody titers to serotype E, as tested by microimmunofluorescence tests. Cross-reactivities occurring in microimmunofluorescence tests were related to the presence of antichlamydial lipopolysaccharide antibodies, adsorption of which by recombinant lipopolysaccharide removed microimmunofluorescence reactivity with C. psittaci antigen. In group 2, significantly more sera had antibodies to C. pneumoniae, remaining after lipopolysaccharide adsorption, as proved by adsorption with viable C. trachomatis and C. pneumoniae organisms. None of the sera had antibodies to Yersinia enterocolitica, Shigella flexneri, Sh. sonnei and Salmonella spp. It was observed that the frequency and titer of cross-reacting antibodies to chlamydial serotypes and species were related to the time period between the diagnosis of genital chlamydial infection and of SARA. Cross-reactivities were also related to the presence of lipopolysaccharide, but not heat shock protein 60- or neutralizing antibodies to chlamydiae. Antibody reactivity induced by antichlamydial lipopolysaccharide antibodies can be removed by lipopolysaccharide adsorption.

Adult↗
PubMed1997

A nonsubstituted primary hydroxyl group in position 6' of free lipid A is required for binding of lipid A monoclonal antibodies.

Lipid A monoclonal antibodies, which require for binding the presence of the bisphosphorylated D-glucosamine disaccharide lipid A backbone, were tested against synthetic lipid A precursor Ia and compound B 1047 by enzyme immunoassay. The last-named compound is a precursor Ia analog with a methoxy instead of a hydroxy group at C6' and was chosen to determine why these antibodies failed to recognize the bound lipid A present in lipopolysaccharide (LPS). Whereas all antibodies tested bound to precursor Ia, none of them bound to compound B 1047 or Escherichia coli Re LPS to a significant extent. Compared to the natural substituent at C6', i.e., 3-deoxy-D-manno-octulosonic acid (Kdo), the methoxy group is neither bulky nor charged. Thus, the data suggest that it is not hindrance by Kdo but rather the generation of a neoantigen that endows lipid A with immunoreactivity upon liberation from LPS by acid hydrolysis.

Antibodies, Monoclonal↗
PubMed1996

Structural and serological characterisation of two O-specific polysaccharides of Acinetobacter.

Extraction of dry bacteria of Acinetobacter strain 34 (DNA group 2) or Acinetobacter strain 108 (DNA group 13) by phenol/water yielded a polymer that was identified by means of serological studies and fatty acid analysis as S-form lipopolysaccharide. Degradation of the lipopolysaccharides of strains 34 and 108 in 1% acetic acid and 5% acetic acid, respectively, and gel-permeation chromatography gave the respective O-antigenic polysaccharides, the structures of which were determined, by compositional analysis and NMR spectroscopy of the polysaccharide, as [Sequence: see text] for strain 108, where D-Fucp3NBuOH represents 3-[(R)-3-hydroxybutyramido] -3,6-dideoxy-D-galactose and D-GalpANAc represents 2-acetamido-2-deoxy-D-galacturonic acid. Both structures were specifically recognised in Western blots by polyclonal rabbit antisera and there was no cross-reaction between these two structures.

Acinetobacter↗
PubMed1995

The structures of oligosaccharide bisphosphates isolated from the lipopolysaccharide of a recombinant Escherichia coli strain expressing the gene gseA [3-deoxy-D-manno-octulopyranosonic acid (Kdo) transferase] of Chlamydia psittaci 6BC.

The lipopolysaccharide from the recombinant strain Escherichia coli F515-140 containing the cloned gene gseA [3-deoxy-D-manno-octulopyranosonic acid (Kdo) transferase] from Chlamydia psittaci 6BC was isolated and sequentially de-O-acylated and de-N-acylated. The products were separated by high-performance anion-exchange chromatography into three fractions, two of which contained a single compound. Their structures were elucidated by high-field NMR spectroscopy as alpha-Kdo-(2-->4)-alpha-Kdo-(2-->6)-beta-D-GlcN-(1-->6)-alpha-D-GlcN 1,4'-P2 (compound 1) (tetrasaccharide bisphosphate) [Holst, O., Broer, W., Thomas-Oates, J. E., Mamat, U. & Brade, H. (1993) Eur. J. Biochem. 214, 703-710] and alpha-Kdo-(2-->4)-[alpha-Kdo-(2-->8)-]-alpha-Kdo-(2-->4)-alpha-Kdo- (2-->6)-beta-D-GlcN-(1-->6)-alpha-D-GlcN 1,4'-P2 (compound 4) (hexasaccharide bisphosphate). The third fraction comprised two pentasaccharide bisphosphates, which could be separated by affinity chromatography using an immobilized monoclonal antibody specific for the trisaccharide alpha-Kdo-(2-->8)-alpha-Kdo-(2-->4)-alpha-Kdo. The bound fraction was identified as alpha-Kdo-(2-->8)-alpha-Kdo-(2-->4)-alpha-Kdo-(2-->6)-beta-D- GlcN-(1-->6)-alpha-D-GlcN 1,4'-P2 (compound 2) [Holst, O., Broer, W., Thomas-Oates, J. E., Mamat, U. & Brade, H. (1993) Eur. J. Biochem. 214, 703-710], whereas the unbound fraction was identified as alpha-Kdo-(2-->4)-alpha-Kdo-(2-->4)-alpha-Kdo-(2-->6)-beta-D-GlcN-(1-->6 )- alpha-D-GlcN 1,4'-P2 (compound 3). This novel Kdo tetrasaccharide extends our knowledge on multifunctional Kdo transferases.

Carbohydrate Sequence↗
PubMed1995

Binding of lipopolysaccharide (LPS) to an 80-kilodalton membrane protein of human cells is mediated by soluble CD14 and LPS-binding protein.

Activation of cells by bacterial lipopolysaccharide (LPS) plays a key role in the pathogenesis of gram-negative septic shock. The 55-kDa glycoprotein CD14 is known to bind LPS and initiate cell activation. However, there must be additional LPS receptors because CD14 is linked by a glycosylphosphatidyl inositol anchor to the cell membrane and therefore unable to perform transmembrane signalling. Searching for potential LPS receptors, we investigated the binding of LPS to membrane proteins of the human monocytic cell line Mono-Mac-6. Membrane proteins were electrophoretically separated under reducing conditions, transferred to nitrocellulose, and exposed to LPS, which was visualized with anti-LPS antibody. Smooth- and rough-type LPS, as well as free lipid A, bound to a variety of proteins in the absence of serum. However, in the presence of serum, additional or preferential binding to a protein of approximately 80-kDa was observed. Experiments with differently acylated lipid A structures showed that the synthetic tetraacyl compound 406 was still able to bind, whereas no binding was detected with the bisacyl compound 606. The 80-kDa membrane protein was also detected on human peripheral blood monocytes and endothelial cells. The serum factors mediating the binding of lipid A to the 80-kDa membrane protein were identified as soluble CD14 and LPS-binding protein. From these results, we conclude that this 80-kDa protein is a candidate for the hypothetical molecule for LPS and/or LPS-CD14 recognition and signal transduction.

Acute-Phase Proteins↗
PubMed1994

Occurrence of antibodies against chlamydial lipopolysaccharide in human sera as measured by ELISA using an artificial glycoconjugate antigen.

An artificial glycoconjugate containing, as a ligand, the deacylated carbohydrate backbone of a recombinant Chlamydia-specific lipopolysaccharide was used as a solid-phase antigen in ELISA to measure antibodies against chlamydial LPS. The specificity and reproducibility of the assay was shown by using a panel of prototype monoclonal antibodies representing the spectrum of antibodies also occurring in patient sera. These mAbs recognized Chlamydia-specific epitopes [alpha 2-->8-linked disaccharide of 3-deoxy-D-manno-octulosonic acid (Kdo) or the trisaccharide alpha Kdo-(2-->8)-alpha Kdo-(2-->4)-alpha Kdo] or those shared between chlamydial and Re-type LPS (alpha Kdo, alpha 2-->4-linked Kdo disaccharide). The assay was used to measure IgG, IgA and IgM antibodies against chlamydial LPS in patients with genital or respiratory tract infections. In comparison to the results obtained with sera from blood donors, it became evident that both types of infection result in significant changes in the profile of LPS antibodies.

Antibodies, Bacterial↗
PubMed1994

Lipopolysaccharide smooth-rough phase variation in bacteria of the genus Chlamydia.

In two strains of Chlamydia psittaci and in Chlamydia trachomatis serotype L1, we have detected a so-far-unknown antigen which (i) is resistant to heat and proteolytic digestion, (ii) can be extracted with phenol-water into the water phase, (iii) gives a ladder-like banding pattern in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, (iv) is immunogenic in rabbits and mice, and (v) contains immunoreactivity of lipid A, a common and characteristic component of gram-negative lipopolysaccharides (LPS). Thus, chlamydiae contain, in addition to the known rough-type LPS, another LPS type which is phenotypically smooth (S-LPS). S-LPS was observed preferentially in chlamydiae grown in the yolk sac of embryonated eggs; it was, however, also detected by immunofluorescence in tissue culture-grown chlamydiae with a monoclonal antibody against S-LPS.

Animals↗
PubMed1993

The antibody reactivity of monoclonal lipid A antibodies is influenced by the acylation pattern of lipid A and the assay system employed.

The influence of the acylation pattern of lipid A on the reactivity of murine monoclonal antibodies (mAb) was tested in different assay systems with synthetic lipid A antigens. Both the number and type of fatty acids had an impact on the antigen amounts needed for optimal sensitization of sheep red blood cells, on the inhibition capacity of compounds and on the reactive antigen amounts in enzyme immunoassay and dot blot assay. Results obtained with two pentaacyl isomers indicated that the location of fatty acids is of no importance. Although all mAbs used recognized epitopes residing in the hydrophilic backbone of lipid A, their reactivities were greatly influenced by the number as well as the type of acyl chains present. In the various assays, the mAbs reacted either similarly or discrepantly suggesting that epitopes are exposed differently in the test systems. We conclude that for the determination of the reactivity of lipid A mAbs it is useful and sometimes necessary to run various assays in parallel and to compare mAbs on the basis of reaction patterns.

Acylation↗
PubMed1993

Specificity of rabbit antisera against the rough lipopolysaccharide of Salmonella minnesota strain R7 (chemotype Rd1P-).

Rabbit polyclonal antibodies against the lipopolysaccharide (LPS) of the Rd1P- mutant strain R7 of Salmonella minnesota were serologically characterized using R7 LPS, dephosphorylated LPS, deacylated LPS, deacylated, dephosphorylated and reduced LPS, and synthetic partial structures. The latter comprised partial structures of the core region of Rd1P- LPS bound to the beta 1-->6-linked glucosamine dissacharide with two amide-linked 3-hydroxytetradecanoic acid residues or artificial glycoconjugates comprised of the synthetic oligosaccharides coupled to bovine serum albumin. Using a passive hemolysis and an enzyme immunoassay, absorption and inhibition experiments, the antibody specificites present could be determined. One group of antibodies required components of the core region and the phosphorylated glucosamine disaccharide of the lipid A moiety for binding. The majority of phosphate-independent antibodies was directed against the trisaccharide L-glycero-alpha-D-manno-heptopyranose(1-->3)- L-glycero-alpha-D-manno-heptopyranose(1-->5)3-deoxy-D-manno-oct ulo sonic acid. Antibodies against the 1-->3- and 1-->7-linked heptose disaccharides and against a single heptose were also detected, however, with low titers. No antibodies were found which required the presence of fatty acids.

Animals↗
PubMed1993

An artificial glycoconjugate containing the bisphosphorylated glucosamine disaccharide backbone of lipid A binds lipid A monoclonal antibodies.

Monoclonal antibodies (MAbs) against lipid A, the endotoxic component of lipopolysaccharide (LPS) of gram-negative bacteria, are presently discussed as therapeutic agents against lethal gram-negative infections; however, their binding specificities are controversial. We have isolated from the LPS of Escherichia coli J-5 the 1,4'-bisphosphorylated beta 1-->6-linked glucosamine disaccharide backbone of its lipid A moiety, which was covalently linked to bovine serum albumin. It was shown by solid-phase enzyme immunoassay that one antibody (MAb A6) bound equally well to the glycoconjugate and synthetic E. coli-type lipid A over a broad range of antigen concentrations whereas two other MAbs (IC3 and S1-15) bound better to the conjugate at low antigen concentrations and better to the lipid A when high concentrations of antigen were used. This proves in a direct way that there exist lipid A MAbs with different specificities which bind to epitopes in the hydrophilic backbone of lipid A and which do not require the presence of fatty acids.

Antibodies, Monoclonal↗
PubMed1993

Specificity of rabbit antisera against the rough lipopolysaccharide of Salmonella minnesota R4 (chemotype Rd2P-)

Rabbit polyclonal antibodies against the rough mutant lipopolysaccharide (LPS) of Salmonella minnesota R4 (chemotype Rd2P-) were serologically characterized by using R4 LPS, deacylated LPS, dephosphorylated LPS, and synthetic partial structures, including compounds comprising the core region of Rd2P- LPS bound to the beta 1-->6-linked glucosamine disaccharide with two amide-linked 3-hydroxytetradecanoic acid residues or coupled to bovine serum albumin. By using a passive hemolysis assay and an enzyme immunoassay and absorption and inhibition experiments, the antibody specificities present could be determined. One group of antibodies required components of the core oligosaccharide (with or without the side chain 3-deoxy-D-manno-octulosonic acid [Kdo]) and the phosphorylated glucosamine disaccharide of the lipid A moiety for binding. The phosphate-independent antibodies were directed against the core oligosaccharide, recognizing an epitope consisting of one terminal heptose linked to Kdo or to the reducing moiety of the alpha 2-->4-linked Kdo disaccharide. Antibodies requiring the presence of acyl residues and those reacting with a single heptose or Kdo residue were not detected.

Animals↗
PubMed1993

[Bacterial endotoxins: relationship between chemical structure and biological effect].

Gram-negative bacteria carry on their surface endotoxins, which are essential for bacterial growth and survival. If released from the bacterial cell, endotoxins induce in higher organisms a great variety of pathophysiological effects. Chemically, endotoxins constitute lipopolysaccharides (LPS), the lipid component (termed lipid A) of which is responsible for the induction of endotoxin effects. The structural and conformational parameters, endowing lipid A with its potent bioactivity, have been well characterized. The toxic effects of endotoxins are initiated by the specific interaction of lipid A with macrophages/monocytes resulting in the production of peptide or lipid mediators. This interaction is governed by a unique (toxic) conformation of lipid A on the one hand, and by specific cellular receptors on the other. The interaction and subsequent mediator production can be specifically and antagonistically inhibited by lipid A partial structures. A recently developed monoclonal anti-LPS-antibody cross-reacts with endotoxins of various bacterial origin, and it cross-protects against harmful endotoxin effects such as pyrogenicity and lethality.

Animals↗
PubMed1992

A complement-dependent enzyme immunoassay (C-EIA) with increased sensitivity for IgM-rich rabbit sera.

An enzyme immunoassay involving activation of complement (C-EIA) was developed for rabbit polyclonal IgM antibodies against lipid A and lipopolysaccharide antigens. C-EIA was significantly higher in sensitivity for IgM-rich rabbit sera compared to EIA using anti-immunoglobulin secondary antibodies. Hence, C-EIA should be useful for the detection of weak IgM reactivities in rabbit sera, especially after short-time immunizations. Selective inhibition of both complement pathways indicated that C-EIA measures activation of the classical pathway.

Animals↗
PubMed1992

Staining of surface antigens of Chlamydia trachomatis L2 in tissue culture.

Surface labeling of chlamydial elementary and reticulate bodies in L929 cells infected with Chlamydia trachomatis serotype L2 was monitored by using monoclonal antibodies (MAb) against the major outer membrane protein and lipopolysaccharide (LPS). Different staining and fixation procedures were used to detect these surface antigens during the developmental cycle. Anti-major outer membrane protein MAb yielded a clear staining pattern of exclusively chlamydial inclusions independent of the fixation or staining technique used. Anti-LPS MAb gave a faint staining pattern of reticulate bodies when methanol fixation was used and showed that LPS was released from chlamydiae into the host cell cytoplasm and into the surroundings of the infected host cell. However, when paraformaldehyde-glutardialdehyde fixation was used, extracellular LPS staining was not observed. The data show that chlamydial LPS is loosely bound in the bacterial outer membrane but suggest that shedding of LPS is a fixation artifact.

Antibodies, Monoclonal↗
PubMed1992

A synthetic glycoconjugate representing the genus-specific epitope of chlamydial lipopolysaccharide exhibits the same specificity as its natural counterpart.

The tetrasaccharide 3-deoxy-alpha-D-manno-2-octulosonic acid (alpha-KDO) (2----8)-alpha-KDO(2----4)-alpha-KDO(2----6)-beta GlcNAc, a partial structure of chlamydial lipopolysaccharide (LPS) representing a genus-specific epitope, was synthesized and covalently linked to bovine serum albumin, resulting in an artificial glycoconjugate antigen. Mice were immunized with the glycoconjugate to prepare chlamydia-specific monoclonal antibodies. They were selected with chlamydia-specific LPS antigens and the structurally and antigenically related Re-type LPS of a Salmonella minnesota rough mutant. Characterization of the selected antibodies was by (i) hemagglutination of sheep erythrocytes coated with recombinant chlamydia-specific LPS, (ii) inhibition by synthetic polyacrylamide derivatives containing the genus-specific epitope or partial structures thereof, (iii) enzyme immunoassay with recombinant LPS and synthetic bovine serum albumin glycoconjugates as solid-phase antigens, (iv) immunofluorescence of L929 monolayers infected with Chlamydia psittaci or C. trachomatis, and (v) Western immunoblots with glycoconjugates and LPS as the antigen. Two groups of monoclonal antibodies were obtained; the monoclonal antibodies in one group cross-reacted with chlamydial and Re-type LPS, but those of the other group were chlamydia specific. Among the latter, KDO trisaccharide-specific antibodies that had the same epitope specificity as antibodies obtained after immunization with chlamydial elementary bodies were identified; however, they exhibited a more than 100-fold higher affinity. In addition, antibodies that bound preferentially to the 2.8-linked KDO disaccharide were detected, although with lower affinity. The data show that the artificial glycoconjugate antigen is similar to its natural counterpart.

Animals↗
PubMed1992

Characterization of the epitope specificity of murine monoclonal antibodies directed against lipid A.

A series of monoclonal antibodies directed against lipid A was characterized by using synthetic lipid A analogs and partial structures. These compounds vary in phosphate substitution, acylation pattern (type, number, and distribution of fatty acids), and, in the case of monosaccharides, in their backbone glycosyl residue. The monoclonal antibodies tested could be subdivided into five groups according to their reactivity patterns. One group reacted exclusively with 1,4'-bisphosphoryl lipid A, and a second also reacted with 4'-monophosphoryl lipid A. Two further groups recognized either 4-phosphoryl or 1-phosphoryl monosaccharide partial structures of lipid A. The fifth group reacted with 4-phosphoryl monosaccharide structures and with phosphate-free compounds. Antibodies reactive with monosaccharide structures also recognized their epitopes in corresponding phosphorylated disaccharide compounds. Both groups of monosaccharide and monophosphoryl lipid A-recognizing antibodies have access to their epitopes in bisphosphoryl compounds as well. Because of this unidirectional reactivity with more complex structures, the various specificities cannot be distinguished by using bisphosphoryl lipid A (e.g., Escherichia coli lipid A) as a test antigen. The epitopes recognized by the various monoclonal antibodies all reside in the hydrophilic backbone of lipid A, and there was no indication that fatty acids were part of the epitopes recognized. Nevertheless, the reactivities of compounds in the different test systems are strongly influenced by their acylation patterns; i.e., acyl groups may modulate the exposure of lipid A epitopes.

Acylation↗