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

Endotoxin has been shown to induce amyloidosis in mice and to result in the appearance in serum of large amounts of amyloidrelated protein (SAA). After injection of 300 mug lipopolysaccharide Escherichia coli, SAA behaves as an acute phase reactant with levels reaching a peak of >600 mug/ml at 18-22 h and returning to base line (<50 mug/ml) by 48 h in each of four strains tested; only the endotoxin-resistant C3H/HeJ strain showed a smaller response. Lesser, though significant, elevations were also found after subcutaneous injection of 25 mg of casein, bovine serum albumin, ovalbumin, or monomeric immunoglobulin G, whereas pyrogen-free human serum albumin/U. S. Pharmacopeia failed to raise SAA levels. SAA generation may thus be a result of endotoxin contamination of these protein preparations. Also present in equivalent amounts in acidified serum from endotoxin-treated mice, but barely detectable in control sera, was a 3,000-dalton molecule whose amino acid sequence is identical to the amino terminal 24 residues of mouse albumin. The appearance of SAA and the amino terminal albumin fragment after endotoxin were unaffected by pretreatment with cobra venom factor, and equivalent levels were found in C5-deficient mice. Pretreatment with pepstatin in vivo, or before acidification in vitro, prevented the appearance of the albumin fragment but had no effect on the appearance of SAA, whereas leupeptin and antipain did not affect the appearance of either SAA or the albumin fragment. These studies suggest that the generation of SAA after endotoxin administration does not involve complement activation or intravascular proteolytic activity, whereas the liberation of a specific peptic-like cleavage product of albumin appears to be the consequence of an acid protease.
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PMID:Some effects of the administration of endotoxin in mice. Specific cleavage of serum albumin by an acid protease and the generation of amyloid serum component. 3 28

Bacterial lipopolysaccharide (LPS) was demonstrated to have the capacity in mice to enhance the response to soluble bovine serum albumin (BSA) and to interfere with the induction of tolerance to human gamma-globulin (HGG). These adjuvant activities were shown to occur under conditions in which LPS could also function as a B cell mitogen. This positive correlation was established by utilizing two experimental situations in which LPS was non-mitogenic for spleen cells. Thus, on the one hand, it was found that LPS did not function as an adjuvant in C3H/HeJ mice, a unique strain whose spleen cells were also unresponsive to LPS-induced mitogenesis. On the other hand, in strains which did respond to LPS mitogenically, LPS failed to function as an adjuvant when it was chemically altered to reduce its in vitro mitogenic activity. A correlation was also observed between mitogenesis and the capacity of LPS to function as a specific immunogen i mice. In contrast to the sustained and prolonged plaque-forming cell response that was observed in mice whose spleen cells were also responsive to LPS-induced mitogenesis, the response was relatively transient in the C3H/HeJ strain. These results are discussed in view of the possible in vivo modes of action of LPS.
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PMID:Immunologic properties of bacterial lipopolysaccharide (LPS): correlation between the mitogenic, adjuvant, and immunogenic activities. 4 49

Experiments were designed to test two hypotheses of B-cell activation by antigen: the cross-linking concept, postulating that a suitable degree of antigen-induced cross-linking of the Ig receptors is sufficient for immunocyte triggering, and the two-signal hypothesis, suggesting that a first signal delivered by antigen interacting with the Ig receptors followed by a second signal given by, for example, a polyclonal B-cell activator is necessary for activation. The results did not support either of these hypotheses. Thus, the hapten FITC coupled to human serum albumin and human gammaglobulin in different conjugation ratios failed to activate B cells, whether the hapten-protein conjugates were soluble or precipitated, whether the experiments were carried out in the presence or absence of different concentrations of sera from different species, and irrespective of the day of assay. Furthermore, the same FITC-protein conjugates or FITC itself coupled to Sepharose particles failed to induce a specific anti-FITC response, even though a range of 10-9-fold concentrations of FITC were used. In contrast, FITC coupled to lipopolysaccharide (LPS) regularly induced a primary anti-FITC response in all the above systems, whether FITC-LPS was soluble or coupled to Sepharose particles. The conjugation ratio of FITC to LPS was within the range of epitope densities used with FITC-protein conjugates. Analogous studies were performed with the above compounds and, in addition, NNP-cap and fowl gammaglobulin, added alone or together with LPS to lymphocyte cultures. In no case did the antigen plus LPS give a better specific anti-FITC response than LPS alone, irrespective of the culture conditions, the epitope densities, the physical form of the conjugates, and whether they were bound to Sepharose particles or not, although this would be expected in terms of the two-signal concept. The results are compatible with the one nonspecific signal hypothesis, ascribing a passive role to the Ig receptors and an active triggering function to thymus-independent antigens. Therefore, the ability to trigger B cells directly will depend on the nature of the carrier, triggering being achieved if the carrier is a polyclonal B-cell activator; the epitope density and the degree of cross-linking of Ig receptors are unimportant for delivering the triggering signal, although they can facilitate the binding of the conjugate to the specific B cells.
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PMID:Mechanism of b-lymphocyte activation: failure to obtain evidence of a direct role of the Ig receptors in the triggering process. 4 77

The octasaccharide Galp (Formula: see text) Rhap, the synthesized disaccharides methyl 3-O-a-tyvelopyranosyl-a-D-mannopyranoside, methyl 3-O-a-tyvelopyranosyl-beta-D-mannopyranoside and methyl alpha-tyveloside, in order of decreasing effectiveness, inhibited the precipitation of S. typhi T2 alkali-treated lipopolysaccharide by O-factor 9 serum. On a molar basis the relative inhibiting activities of the glycosides were by O-factor 9 serum. On a molar basis the relative inhibiting activities of the glycosides were 100:22:8:2. With rabbit aniserum raised against 3-O-a-tyvelopyranosyl-D-mannopyranosyl covalently linked to bovine serum albumin the relative inhibitory activities of the four glycosides were 11:100:26:3. These data establish that the 3-O-a-tyvelopyranosyl-a-D-mannopyranosyl structure is immunodominant in the Salmonella O-antigen 9. The specificity of the antigen-antibody interaction was high: glycosides in which the tyvelose (3,6-dideoxy-D-arabino-hexose) residue had been replaced by abequose (3,6-dideoxy-D-xylo-hexose) or paratose (3,6-dideoxy-K-ribo-hexose), had less than one fiftieth of the activity of the most active inhibitor in either of the two precipitation systems used. Moreover, the results show that 3-O-a-tyvelopyranosyl-D-mannopyranosyl coupled to bovine serum albumin elicits O-antibodies of higher specificity than those obtained by absorption of antibacterial immune serum.
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PMID:Immunochemistry of Salmonella O-antigens. Specificity and cross-reactivity of factor O9 serum and of antibodies against tyvelose (Formula: see text) mannose coupled to bovine serum albumin. 8 96

T cell dependency of antibody response to polyvinylpyrrolidone (PVP), sheep red blood cells (SRBC), bovine gamma globulin (BGG), and bovine serum albumin (BSA) was examined. PVP and the other three are known as a T cell-independent antigen and T cell-dependent antigens respectively. Adult mice were thymectomized, X-irradiated, reconstituted with syngeneic bone marrow cells (TxXB mice), with bone marrow cells plus thymus cells (TxXBT mice), or with bone marrow cells treated with anti-Thy-1.2 serum and complement (TxXB-theta mice) and used as experimental animals. The anti-PVP response of TxXBT mice was significantly lower than that of TxXB mice, suggesting that T cells exerted a suppressive effect on the response to PVP. Both IgM and IgG responses to SRBC and BGG occurred even in TxXB-theta mice with the aid of bacterial lipopolysaccharide (LPS). However, a significant response to BSA was not observed in TxXB mice even in the presence of LPS or several other adjuvants. These results indicate that the T cell dependency of antigens is different among so called thymus-dependent antigens, that antibody response less dependent on the helper action of T cells can be supported by LPS in the absence of T cells, and that anti-BSA response seems to be extremely T cell dependent.
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PMID:Hierarchy of T cell dependency in antibody response among different antigens. 9 45

Rat IgM and IgG was determined by mechanized "sandwich" enzyme-linked immunosorbent assay (ELISA) using peroxidase labeled anti-rat-IgM and -IgG. Linear ranges in standard curves of a reference rat serum had a slope similar to the slopes found with sera of 25 rats of various age. IgM and IgG measurements by ELISA in these sera correlated well with results obtained by single radial immuno-diffusion (SRID). In addition, the precision of the enzyme immunoassay was the same as obtained with the SRID. Compared with SRID, ELISA is less time consuming and the amount of antiserum used in the macro-ELISA is one order of magnitude lower; and again 10 times lower in the mechanized micro-ELISA that is currently being developed. In conclusion, the ELISA is a specific, reliable, sensitive, and economic method for routine measurement of rat serum IgG and IgM e.g. in toxicity studies. In the second part of this study, ELISA and the passive hemagglutination test were compared to determine the primary and secondary antibody response to E. coli lipopolysaccharide (LPS) and tetanus toxoid in rats. In the ELISA, the antigens were bound to the wells of polystyrene microplates. Tetanus toxoid was coated directly, LPS after complexing with methylated bovine serum albumin. After incubation with dilutions of the rat sera, the amount of antibody bound to the solid phase was quantified by means of peroxidase-labeled antiimmunoglobulin. The specificity of the enzyme immunoassay was tested by absorption of the sera with the respective antigens. ELISA proved to be more sensitive than the hemagglution reaction, except when titers were determined during the secondary response to tetanus toxoid. Besides its specificity and sensitivity, ELISA is a convenient method for measuring both IgM and IgG antibodies. Finally, evidence is presented that in the rat, the humoral immune response to LPS is a thymus-independent phenomenon. Thus, by using the antibody response to LPS and tetanus toxoid in function studies of the immune system of the rat, insight can be obtained in the thymus-independent and thymus-dependent humoral immune response.
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PMID:Quantification of total IgM and IgG and specific IgM and IgG to a thymus-independent (LPS) and a thymus-dependent (tetanus toxoid) antigen in the rat by enzyme-linked immunosorbent assay (ELISA). 11 Feb

An artificial antigen was prepared from 4-O-beta-I-galactopyranosyl-D-glucose (lactose) and 8-ethoxycarbonyloctanol. Covalent attachment to bovine serum albumin provided an antigen that elicited antilactose antibody in rabbits and goat. These antibodies were active against Neisseria gonorrhoeae lipopolysaccharide in passive hemagglutination tests. The same antibody agglutinated cells of Streptococcus faecalis, strain N, and precipitated the lactose-containing cell wall diheteroglycan of this organism. Fractionation of rabbit and goat antibody raised against the synthetic antigen of S. faecalis vaccine provided two antibody fractions only one of which, eluted from the immunoadsorbent by galactose, was active against N. gonorrhoeae lipopolysaccharide.
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PMID:Antibody to an artificial disaccharide antigen cross-reactive with Neisseria gonorrhoeae lipopolysaccharide. 11 Apr 27

Concanavalin A (Con A) injected intraperitoneally at a dose of 50 mg per kg was not lethal for male BALB/c mice. Six hours after administration of 5 mg Con A/kg, the proportioy 24 hr, the proportion of granulocytes had decreased to 56%. Adiministration of 5 mg Con A/kg 24 hr before 200 mg of 5[3,3-bis(2-chloroethyl)-triazeno]-imidazole-4-carboxamide per kg, or 100 mg of 5-fluorouracil per kg resulted in a significant enhancement of lethality. Simulatenous administration of 5 mg Con A/gm and 10 mg of daunomycin per kg also resulted in enhanced lethality. Administration of 5 mg Con A/kg 24 hr before 40 mg of 1,3-bis(2-chloroethyl)-1-nitrosourea per kg, 200 mg of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea per kg, 1000 mg of cytosine arabinoside per kg, 0.1 mg of mithramycin per kg, 2 mg of pactamycin per kg or 1 mg of vincristine per kg did not result in enhanced lethality. Lipid A prepared from Escherichia coli 0127:B8 Boivin lipopolysaccharide has been complexed to Con A. The lipid A-Con A complex (5mg/kg) was no more, or less effective in enhancing the lethality of 5-fluorouracil than 2.5 mg Con A/kg. The lipid A-Con A complex (40 mg/kg), given simultaneously with drug, enhanced lethality per kg. In this regard, the lipid A-Con A complex had vincristine per kg. In this regard, the lipid A-Con A complex had activity comparable to the complex formed between lipid A and bovine serum albumin. Conceivably, Con A can be used to enhance the susceptibility of neoplastic cells to phase-specific antitumor drugs, especially those acting on deoxyribonucleic acid synthesis.
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PMID:Enhanced cytotoxicity in mice of combinations of concanavalin A and selected antitumor drugs. 16 46

Mice depleted of T cells by adult thymectomy, X-irradiation and reconstitution with syngeneic bone marrow cells, either untreated or treated with anti-Thy-1 serum and complement, were immunized intensively with alum-precipitated bovine serum albumin (AP-BSA) along with or without bacterial lipopolysaccharide (LPS), but no significant anti-BSA antibody response was detected. Priming of the T-cell depleted mice, however, either by a single injection of AP-BSA plus LPS or by multiple injections of AP-BSA without LPS, resulted in the generation of immunological memory. A single injection of AP-BSA without LPS was ineffective. The memory required the aid of syngeneic T cells to be recalled by the challenge with AP-BSA plus LPS. On the other hand, multiple injections of AP-BSA plus LPS did not cause the generation of memory and the response of these mice to the challenge was lower than that of unprimed control mice. These results suggest that (1) the anti-BSA response is highly dependent on the helper function of T cells, (2) the degree of T-cell requirement for the memory generation is very low, and (3) priming with too much strong stimulation in the absence of functional T cells leads to the suppression or abortion of previously generated immunological memory.
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PMID:Studies on B-cell memory. I. Generation and exhaustion of B-cell memory by thymus-dependent antigen in T-cell depleted mice. 31 22

Heat-stable enterotoxin (ST) produced by porcine strains of enterotoxigenic (ENT+) Escherichia coli has been purified to apparent homogeneity by sequential ultrafiltration, acetone fractionation, preparative gel electrophoresis, diethylaminoethyl Bio-Gel A ion-exchange chromatography, and Bio-Gel P-10 gel filtration. The enterotoxin, purified more than 1,500-fold, exhibited a molecular weight of 4,400, as determined by both sodium dodecyl sulfate-gel electrophoresis and gel filtration. A molecular weight of 5,100, representing 47 residues, was calculated from amino acid analysis data. The amino acid content was distinctive, with an unusually high proportion of cystines and few hydrophobic amino acids. A single amino-terminal residue, glycine, was observed. Purified ST was stable to heating (100 degrees C, 30 min) and did not lose biological activity after treatment with Pronase, trypsin, proteinase K, deoxyribonuclease, ribonuclease, and phospholipase C. Periodic acid oxidation and several organic solvents (acetone, phenol, chloroform, and methanol) had no effect on the biological activity of ST. Further, purified ST was stable to acid treatment at pH 1.0 but lost biological activity at pH values greater than 9.0. Neither lipopolysaccharide nor lipid contamination was evident in purified preparations. A characteristic absorption spectrum was observed during the course of the purification, which shifted from a maximum at 260 nm in crude preparations to 270 nm for the purified toxin. Antiserum obtained from rabbits immunized with ST or ST coupled to bovine serum albumin neutralized the action of the enterotoxin in suckling mice; however, passive hemagglutination and hemolysis titer assays suggested that ST is a poor antigen.
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PMID:Purification and chemical characterization of the heat-stable enterotoxin produced by porcine strains of enterotoxigenic Escherichia coli. 34 81


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