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

Carrageenan, a sulfated polygalactose having macrophage toxic properties, elicited a marked suppression of IgM response to T cell-dependent antigens such as sheep red blood cells (SRBC), dinitrophenylated bovine serum gamma-globulin (DNP-BGG), and trinitrophenylated concanavalin A (TNP-Con A). In contrast, carrageenan did not inhibit antibody responses to such T cell-independent antigens as trinitrophenylated DEAE-dextran (TNP-DEAE-dextran), trinitrophenylated polyvinyl pyrrolidone(TNP-PVP), and trinitrophenylated Ficoll (TNP-Ficoll). Compared to total spleen cells, spleen cells from which macrophages had been removed by adhesion to plastic Petri dishes had less effect on the production of antibody against T cell-dependent antigens, but no change or a rather stimulated effect was observed in in vitro antibiody synthesis against T cell-independent antigens. These results strongly suggest that macrophages are involved in antibody responses to T cell-dependent antigens but not in those to T cell-independent antigens. However, the antibody response to trinitrophenylated lipopolysaccharide (TNP-LPS), a T cell-independent antigen, was inhibited by carrageenan treatment, suggesting that the response is macrophage dependent. Moreover, antibody response to higher doses of dinitrophenylated phytohemagglutinin (DNP-PHA), a T cell-dependent antigen, was shown to be macrophage independent by carrageenan treatment, although the antibody response to low doses of the antigen was macrophage dependent. Considering all these results, carrageenan treatment seems to be a very useful method to determine whether immune response to various antigens are macrophage dependent or not.
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PMID:Effects of carrageenan on immune responses. Studies on the macrophage dependency of various antigens after treatment with carrageenan. 6 80

Five methods were employed to determine the heterogeneity or homogeneity of lipopolysaccharides from four acholeplasmal species, Acholeplasma axanthum, A. granularum, A. laidlawii, and A. modicum. A axanthum lipopolysaccharide behaved as a single component in all tests. A. granularum exhibited two components of identical composition and antigenic specificity. A. modicum lipopolysaccharide behaved as three components in two tests, but all three were similar in composition and identical serologically. The separable components of lipopolysaccharides from A. granularum and A. modicum probably represent size differences only. A. laidlwii lipopolysaccharide contained two distinct components by all methods. One was identified as the previously reported amino sugar polymer, whereas the other was a lipopolysaccharide containing both neutral and amino sugars.
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PMID:Homogeneity of lipopolysaccharides from Acholeplasma. 6 11

One the cell surface of smooth of Yersinia enterocolitica 75 (Ye 75 S), and electron-lucent layer was identified in thin sections after incubation with Ye 75 S-antiserum. It is adjacent to the "double track" of the outer membrane. This layer does not appear on the analogously treated rough mutant (Ye 75 R), whose lipopolysaccharide (LPS) does not contain O-specific polysaccharides. It could be shown that this layer is formed by the O-specific side chains of LPS, which are unstained by routine methods. As the side chains of LPS obviosly make it difficult to visualize the LPS-strands in the outer membrane of rough strands was investigated. On Ye 75 R, the LPS-strands could be demonstrated only after treatment of cells with polymyxin B. After short time of exposure, the LPS appeared as contigous strand-like structures (diameter roughly 60 A) on the cell surface of cells which were negatively stained or dried by the critical-point-method. After prolonging polymyxin B treatment, "blebs" or "protrusions" appeared on the surface of Ye 75 cells, which were in negatively stained preparations and in thin sections identified as partly loosened LPS. The demonstration of LPS-strands in untreated cells was possible only on a "deep rough" mutant (Ye 161-45 a R), whose LPS contains only glucosamine and KDO besides lipid A. It is suggested that the LPS form a layer of contiguous strands (mid-to-distance 62 +/- 3 A) on the surface of negatively stained cells. According to this view, on the Ye 75 S, the O-specific side chains extend from this layer into the medium.
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PMID:The arrangement of lipopolysaccharides on the outer membrane of Yersinia enterocolitica: an electron microscopic study. 6 41

The capacity of the trinitrophenyl (TNP) haptenic group, coupled to a series of chemically dissimilar carriers, to cross-stimulate putative T- dependent and T-independent murine B-cell subpepulations was determined by using an in vitro limiting dilution technique to generate primary IgM responses. It was found that TNP-Ficoll and TNP-dextran, two T- independent antigens with little or no polyclonal mitogenicity, stimulate the same population of anti-TNP precursors, which is distinct from the precursor population activated by TNP-bacterial lipopolysaccharide (LPS), a T-independent polyclonal mitogen, or TNP-horse erythrocytes (HRBC), a T-dependent antigen. On the other hand, TNP-LPS and TNP-HRBC activate the same precursor population, indicating that LPS can substitute for the T- cell signal in T-dependent B-cell responses, whereas nonmitogenic T- independent antigens cannot. However, the cumulative evidence from this and other laboratories strongly indicates that LPS and T-dependent antigens activate B cells by different mechanisms. Of particular interest, LPS is incapable of activating B cells responsive to weakly- or nonmitogenic T-independent antigens. Based on clonal burst size, T-dependent antigens are capable of inducing greater antigen-specific B-cell proliferation than T-independent antigens. However, TNP conjugates of Ficoll and dextran, which are relatively poor inducers of polyclonal B-cell activation, induced larger anti-TNP clones than did TNP-LPS, a strong polyclonal mitogen. The findings reinforce the evidence favoring existence of multiple B- cell subpopulations with distinctive activation pathways. They also strengthen the proposition that a given B-cell subset can be activated by more than one mechanism.
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PMID:Carrier-directed anti-hapten responses by B-cell subsets. 6 86

Mice were rendered specifically tolerant to the fluorescein isothiocyanatedextran (FITC) epitope by injection of FITC-dextran B512. Their spleen cells were removed at various times and cultivated in vitro with different polyclonal B-cell activators, such as lipopolysaccharide (LPS), purified protein derivative of tuberculin, and native dextran. LPS caused the appearance of high affinity anti-FITC plaque-forming cells to an equal extent with cells from untreated and tolerant animals, whereas native dextran failed to activate cells from tolerant mice, although it was a potent activator of normal cells. It was concluded that tolerance induction only affects those B cells that could respond to the polyclonal B-cell-activating properties of the tolerogen, but not other B cells having an identical set of Ig receptors directed against the tolerogen.
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PMID:Induction of immunological tolerance requires that the B cells can respond to the polyclonal B-cell-activating properties of the thymus-independent antigens. 6 93

Rabbits were immunized with Salmonella minnesota Re mutant bacilli or lipid A, and the serological responses were compared. Re lipopolysaccharide and lipid A were found to possess distinct antigenic determinants as measured by hemagglutination, hemolysis, and precipitin techniques. Lipid A preparations from several enterobacterial and non-enterobacterial species were shown to cross-react in agar gel precipitation reactions. In contrast, preparations from bacilli that do not contain glucosamine as an integral part of their lipid A structure did not demonstrate cross-reactivity with enterobacterial lipid A. Antibody to smooth heterologous bacilli present in some antisera prepared against Re bacilli or lipid A was directed specifically against the smooth lipopolysaccharide and not against the Re or lipid A determinants, demonstrating a nonspecific mitogenic response. Precipitation and immunofluorescence tests indicated that the Re determinant was available on smooth bacilli for reactions with specific antisera but that the lipid A determinant was not.
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PMID:Immunization with R mutants of Salmonella minnesota. II. Serological response to lipid A and the lipopolysaccharide of Re mutants. 6 13

By a series of chromatographic procedures involving precipitation by salt, gel filtration, anionic exchange, and hydroxyapatite elution, a protein--termed the lipopolysaccharide inactivator (LPS-I)--has been isolated from normal human serum. As a result of treatment of bacterial lipopolysaccharide (LPS) by LPS-I, the treated LPS loses its toxicity for mice and reactivity in the Limulus assay and appears to be irreversibly disaggregated. The inactivation of the LPS by the purified LPS-I is temperature and time dependent and is not blocked by the addition of irreversible inhibitors of serine esterases. The LPS inactivator migrates as an alpha-globulin in whole serum and has a sedimentation velocity of approximately 4.5S. Characteristics of the inactivated LPS are briefly described using internally labeled LPS.
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PMID:Isolation from human serum of an inactivator of bacterial lipopolysaccharide. 7 Jan 73

Escherichia coli K100 produces an antigenic determinant similar to, or identical with, the capsular antigen of Haemophilus influenzae type b. Studies of the effects of heat on the immunogenicity, erythrocyte-modifying capacity, and antigenicity of this cross-reacting antigen (CRA) revealed the following findings. Immunization of rabbits with viable or formaldehyde-killed suspensions of E. coli K100, producing CRA, engendered CRA antibodies in significant titers, as demonstrated by hemagglutination of erythrocytes modified by H. influenzae type b antigen. Heating of the suspensions for 1 h at 56 or 100 degrees C destroyed the immunogenicity of CRA, and the heated suspensions did not prime for a secondary antibody response. Supernatants of heated suspensions also were non-immunogenic. Repeated freezing and thawing of heated suspensions of E. coli K100 or their supernatants did not restore immunogenicity. Heat also abolished the immunogenicity of H. influenzae type b. The loss of immunogenicity of CRA of E. coli K100 by heat was not due to alteration of the antigenic determinant, since heated suspensions and supernatants thereof modified erythrocytes for agglutination by H. influenzae type b antiserum. The latter supernatants also inhibited hemagglutination by H. influenzae type b antibodies and absorbed the latter. We conclude that striking differences exist in the effects of heat on CRA on the one hand and of enterobacterial common antigen and lipopolysaccharide O antigen of enteric bacteria on the other. Heating of the latter two antigens does not abolish their priming effect, and repeated freezing and thawing restores the immunogenicity of heated antigens.
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PMID:Effect of heat on antigenicity and immunogenicity of the antigenic determinant shared by Haemophilus influenzae type b and Escherichia coli K100. 7 Dec 69

A new procedure involving inhibition of a solid-phase radioimmunoassay was developed for specific determination of the outer-membrane protein and the lipopolysaccharide (LPS) serotypes of meningococci. Antigen was allowed to bind to the wells of a polyvinyl microtiter plate and then reacted with a limiting amount of homologous antibody which had been preincubated with buffer or a standard concentration of inhibiting antigen. The amount of antibody bound per well was quantitated by incubation with excess 125I-labeled goat anti-rabbit immunoglobulin. Typing sera for detecting eight LPS antigens and 18 protein antigens were made in rabbits by use of both the group C and group B bactericidal serotyping strains. Reactions between unabsorbed sera and purified LPS were inhibited in the LPS typing system, whereas reactions between absorbed sera and outer-membrane complex were inhibited in the protein typing system. Outer-membrane complex was used as the inhibiting antigen in both cases. Approximately 97% of the 80 group B and C strains tested were LPS typable, and 80% were protein typable. Of 51 group A strains tested, however, only 22% were LPS typable and 14% were protein typable. Several nonreciprocal correlations between the occurrence of particular LPS and protein serotype antigens on the same strain were observed, but in general the protein and LPS serotype antigens appeared to occur independently.
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PMID:Outer-membrane protein and lipopolysaccharide serotyping of Neisseria meningitidis by inhibition of a solid-phase radioimmunoassay. 7 35

Suppression of the plaque-forming cell response in mice following injection of substances fractionated from pooled normal serum alpha-globulin was investigated. The dose-response relationship for fractions obtained by ion-exchange chromatography show that a single preparation has both enhancing and suppressive activities which are revealed at different doses. Whether this observation reflects the sum of activities of a number of molecular species remains to be determined. The immune responses to both thymus-dependent (heterologous erythrocytes) and thymus-independent (DNP-ficoll) antigens are suppressed while the response to the thymus-independent antigen lipopolysaccharide is enhanced. Thus, the cellular locus for immunosuppression cannot be exclusively on the T cell, and the magnitude of the action of the two populations (T and B cells) remains unclear.
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PMID:Serum-derived immunosuppressive substances. III. Regulation of the immune response by human serum alpha-globulin fractions: the dose-response relationship. 7 12


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