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

Nearly 100 isolates of Lactobacillus were obtained from human and animal sources. Screening tests with the isolates revealed seven possible bacteriocinogenic strains and 26 strains sensitive to one or more of these inhibitory strains. Three homofermentative strains were selected for additional study after it was shown that their inhibitory substances differed in activity spectrum and in susceptibility to inactivation by proteolytic enzymes. One of these, L. helveticus strain LP27, was shown to produce a potent bacteriocin called lactocin 27. The lactocin was isolated from the culture supernatant fluid as a protein-lipopolysaccharide complex. In the presence of sodium dodecyl sulfate the complex was dissociated, and the activity was found to reside in a small glycoprotein (molecular weight 12,400). The amino acid composition of purified lactocin 27 is similar to that of the L. fermenti bacteriocin; neither requires disulfide bonds for activity.
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PMID:Isolation and characterization of a bacteriocin from a homofermentative Lactobacillus. 479 8

Number and affinity constant of low affinity binding sites of insulin and glucagon to isolated hepatocytes decreased when the cells were incubated with Escherichia coli 0111:B4 lipopolysaccharide. This effect agrees with a non-specific binding of lipopolysaccharide to hepatocytes, similar to the well-recognized non-specific binding of albumin. Also, binding of different lectins to their glycoprotein receptors did not affect the [14C]lipopolysaccharide interaction with the cell membrane surface. Endotoxin depresses gluconeogenesis from lactate when the precursor was incubated with the cells for short time intervals. The longer the preincubation interval with lipopolysaccharide, the higher the inhibition of gluconeogenesis in the absence and in the presence of glucagon. The effect of endotoxin was also studied on the glucagon-induced synthesis of cyclic AMP and the glucagon binding. Levels of cyclic AMP and hormone binding decreased with increasing both endotoxin concentrations and preincubation intervals at which cells were in contact with endotoxin.
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PMID:Effect of Escherichia coli lipopolysaccharide on the glucagon and insulin binding to isolated rat hepatocytes. 609 7

The data reported in this paper are the first demonstration that different T cell clones (PC-AKR-CI 96, clone 96; PK 7.1.2 E8, clone 7.1.2 E8) secrete different macrophage-activating factors (MAF) that induce distinct macrophage activities. Incubation of resident murine macrophages with MAF 7.1.2 E8 increased RNA, protein, and glycoprotein synthesis, hexosemonophosphate shunt (HMPS) activity, release of oxygen metabolites (O-2, H2O2), pinocytosis, phagocytosis, and tumor cytostasis, whereas no effect on prostaglandin E (PGE) release, schistosomula killing, and tumor cytolysis could be observed. In contrast, MAF 96 increased glycoprotein synthesis, HMPS activity, release of oxygen metabolites and PGE, schistosomula killing, and tumor cytostasis and cytolysis, whereas RNA and protein synthesis and pinocytosis were decreased and phagocytosis remained unaffected. Thus, MAF from both T cell clones share some macrophage-activating properties but differ in others. Most importantly, both MAF could be differentiated serologically by a rabbit anti-lymphokine antiserum that selectively inhibited MAF 96 but not MAF 7.1.2 E8 activity. At optimal concentrations, MAF 96 and 7.1.2 E8 were active in the absence of lipopolysaccharide (LPS) whereas LPS enhanced the activity of suboptimal doses of MAF 96 but not of MAF 7.1.2 E8. These data are discussed with respect to the possibility that the functional dichotomy of T cell clones might reflect different activities of normal T cell subpopulations.
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PMID:Macrophage-activating factors from different T cell clones induce distinct macrophage functions. 619 Sep 40

Two mouse monoclonal antibodies to chicken immunoglobulin VH-associated idiotypes (Id), CId-1 and CId-2, were used as probes for Id determinants on mouse T cells. CId-1, which recognized chicken antibodies to N-acetyl glucosamine (NAGA), and approximately 0.4% of chicken T lymphocytes also reacted with approximately 0.2% of BALB/c splenic Thy-1.2+ cells. When enriched CId-1+ splenic T cells from NAGA-immune BALB/c mice were fused with the AKR thymoma BW 5147 cell line, 2 of 72 resulting hybrids, termed CId-1A and CId-1B, were reactive by indirect immunofluorescence with the CId-1 antibody. CId-1 determinants were expressed both in the cytoplasm and on the cell surface. Immunofluorescence studies revealed that both CId-1+ T cell hybrids were phenotypically identical: CId-2-/Ig-/Lyt-1+2-/Thy-1.2+/II-2d+/I-Ad-/I-Ak-/I-Jd+/I-Jk+. Incubation of CId-1B hybrid cells with concanavalin A or lentil lectin resulted in capping of the CId-1 determinant, whereas incubation with pokeweed mitogen, lipopolysaccharide, phytohemagglutinin, and wheat germ agglutinin had no effect on the cell surface distribution of the CId-1 molecule. Trypsin or pronase treatment resulted in the loss of detectable CId-1 determinant on the cell surface. Treatment of CId-1B cells with tunicamycin also reduced the immunofluorescence intensity of the surface CId-1 determinant, but had no effect on its cytoplasmic expression. CId-1 antibody-induced capping of the CId-1 marker did not affect the surface distribution of Lyt-1, Thy-1.2, H-2d, I-Jd, or I-Jk molecules. Conversely, capping of I-Jd and I-Jk determinants did not alter the surface distribution of CId-1. These results suggest that the CId-1 determinant is on a glycoprotein that is not physically linked to the Lyt-1, Thy-1.2, H-2d, I-Jd, and I-Jk molecules. The clonal restriction of CId-1 expression by T cells suggests that the CId-1+ molecule could be a T cell antigen receptor.
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PMID:T cell hybrids that express a VH idiotope-related determinant on a glycoprotein distinct from H-2, Thy-1, and Lyt-1 molecules. 619 22

The receptor specificity of H-2-restricted T lymphoblasts activated against trinitrobenzene sulfonate (TNBS)-coupled spleen cells was examined using an antigen binding assay. A population of Lyt-1+,2-T lymphoblasts acquired syngeneic Ia determinants during 4 days of primary culture with hapten-coupled stimulator cells. Syngeneic Ia was not reexpressed after trypsin treatment of the T cells, but was found after incubation with soluble Ia shed from lipopolysaccharide-activated blasts. Self-Ia binding was specific in that Lyt-1+,2- but not Lyt-1-,2+ cells acquired the antigen, and in that self-Ia bound more effectively than allogeneic Ia material. To determine the relationship of self-Ia binding to the recognition of foreign antigen, the binding of trinitrophenyl (TNP)-coupled plasma membrane vesicles by TNP-specific T cells was studied. TNP-vesicle binding occurred via TNP and H-2(Ia) molecules on the vesicles in that binding was inhibited with antibodies against TNP or H-2(Ia) molecules but not non-major histocompatibility complex (e.g., Ly-6.2) molecules on the vesicles. Complete inhibition of TNP-vesicle binding by an Iak-restricted TNP-specific T-cell line occurred with soluble TNP-lysine, but not an unrelated hapten, N-iodoacetyl-N-(5-sulfonic-1-naphthyl)ethylenediamine (I-AED)-cysteine. Conversely, I-AED-cysteine, but not TNP-lysine, inhibited binding of I-AED-coupled B6 vesicles by B6 anti-I-AED T cells. Significant, but weak inhibition of TNP-vesicle binding by the anti-TNP line was observed with glycoprotein preparations containing partially purified self-Ia molecules. However, inhibition was specific for I-Ak molecules, in that inhibition was lost after removal of I-Ak molecules from the glycoprotein preparation, and very little inhibition occurred with soluble glycoproteins prepared from thymocytes which contained very little Ia material or from LPS blasts of an unrelated H-2 haplotype. These results suggest a recognition model in which TNP and Ia determinants are recognized by neighboring receptor combining sites.
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PMID:Receptor specificity of Ia-restricted T lymphoblasts activated against trinitrobenzene sulfonate-coupled spleen cells: recognition of distinct trinitrophenyl and Ia moieties. 619 19

Cloned, Lyt-1+,2-, antigen-specific, Ia-restricted T cell lines can inhibit the growth of Ia-bearing B lymphoma cells in the presence of specific antigen. This effect is due to cytolysis of the B lymphoma cells in an antigen-specific, Ia-restricted manner by the cloned T cell lines. These cloned T cell lines can also kill lipopolysaccharide-activated normal B cells, while they activate resting B cells to divide and secrete immunoglobulin and are thus helper T cells as well as cytolytic T cells. The mechanism of cytolysis was examined in detail. Killing was mediated by a nonspecific mechanism after specific stimulation of the T cells with antigen presented in the context of the appropriate Ia glycoprotein complex, possibly implying a role for a soluble mediator. This simple system involving two clonal populations allows a detailed analysis of T-B interactions. Our studies are consistent with the view that both cognate and noncognate interactions of Ia-restricted T cells with B cells are mediated by nonspecific factors. Thus, the difference between interactions that appear to be cognate and those that appear to be noncognate may be quantitative rather than qualitative. That two cloned populations of cells can show either pattern of interaction depending on T-B ratio provides strong support for this view. Finally, that cloned helper T cells can kill activated B cells in an antigen-specific fashion may provide a new mechanism of immune regulation that would be especially important in responses to self antigens in vivo.
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PMID:Cloned helper T cells can kill B lymphoma cells in the presence of specific antigen: Ia restriction and cognate vs. noncognate interactions in cytolysis. 620 35

The reticulum cell sarcomas (RCS) of SJL/J mice are of particular interest since they readily induce the proliferation of syngeneic T-lymphocytes. Previous cellular studies examined the antigens on the RCS which stimulated this response and suggested that the tumor expressed allogeneic I-region-associated (Ia) antigens normally associated with the E alpha:E beta molecular complex (S. M. Wilbur and B. J. Bonavida, Exp. Med., 153: 501-513, 1981). These particular Ia glycoproteins are not expressed on normal SJL/J cells due to a defect in the E alpha polypeptide synthetic pathway. However, the E beta subunit is synthesized normally by these animals but remains intracellular. The SJL/J-derived RCS may circumvent this defect in E alpha subunit biosynthesis. The aberrant synthesis of this polypeptide is thought to allow membrane presentation of an intact pseudoallogeneic Ia glycoprotein which utilized the normally dormant E beta s polypeptide. In the present study, two monoclonal antibodies directed against the Ia.7 specificity of the E alpha chain (13/18, 14-4-4S) were used to examine more directly the expression of this polypeptide on the tumor. Surprisingly, neither antibody was effective against the RCS in a direct complement-mediated cytolysis assay. Nevertheless, the tumor was found to specifically adsorb lytic activity of both the monoclonal antibodies. In addition, both a cold-cell competition assay and indirect immunofluorescence corroborated the data and indicated that the RCS does express detectable levels of the Ia.7 antigen. Normal spleen cells and lipopolysaccharide B-derived blasts from SJL/J mice were found in all experiments to be devoid of any specific reactivity with these monoclonal antibodies. In addition, continued in vivo passage of transplantable RCS was found to cause down-modulation of the Ia.7 specificities on these tumors. Newer RCS transplantable lines, however, expressed demonstrable levels of this alloantigen in both cellular and serological assays. The observed down-modulation could explain the difficulties encountered in defining this specificity on long-term transplantable RCS. In conclusion, the present serological study corroborates the early cell-binding data. An Ia.7 antigen is shown to be expressed on the RCS, yet this specificity could not be detected on normal SJL/J cells.
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PMID:Serological demonstration of an allogeneic Ia.7 antigen on the cell surface of SJL/J-derived reticulum cell sarcomas. 634 68

Rabbit aortic smooth muscle cells cultivated with certain antisera underwent growth changes and necrosis. These cytotoxic antisera were obtained by immunizing rabbits against rat aorta, human or pig aortic glycoproteins, human serum glycoproteins and E. coli lipopolysaccharide. These different antigens share some biochemical characteristics, and contain four main amino acid residues (Glu, Ala, Asp, Gly) and four sugars (mannose, galactose, glucose, N-acetyl glucosamine). The cytolytic properties of these antisera, however, probably correspond to structural analogies, since although ovalbumin is a glycoprotein, anti-ovalbumin antiserum was not cytotoxic. Antibody cytotoxicity against rabbit arterial smooth muscle cells may depend on the biochemical structure of the antigen used to produce antiserum.
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PMID:In vitro immune aggression against rabbit aortic smooth muscle cells. 637 15

The data reported in this paper demonstrate that macrophage-activating factors (MAFs) are a heterogeneous group of T-cell-derived lymphokines. Two long-term T-cell clones, Cl 96 and PK 7.1.2E8, were potent sources of MAFs (MAF96 and MAF7.1.2E8). These MAFs could be distinguished by differential activation of macrophages. Activation of resident murine macrophages with MAF7.1.2E8 enhanced RNA and glycoprotein synthesis, hexosemonophosphate shunt (HMPS) activity, release of oxygen metabolites (O-2 and H2O2), pinocytosis and tumor cytostasis, whereas no effect on schistosomula killing and tumor cytolysis could be observed. In contrast, MAF96 enhanced glycoprotein synthesis, HMPS activity, release of oxygen metabolites and prostaglandin E, schistosomula killing, and tumor cytostasis and cytolysis, while RNA synthesis and pinocytosis were decreased. These findings show that MAFs from both T-cell clones share some properties but markedly differ in others. In addition, the macrophage-activating properties of MAF96 but not of MAF7.1.2E8 could selectively be inhibited by a rabbit anti-lymphokine antiserum. This demonstrates a serological difference between MAF activities from both clones. Although at optimal concns both MAFs were active in the absence of lipopolysaccharide (LPS), the activity of suboptimal doses of MAF96 but not of MAF7.1.2E8 could be enhanced by LPS. These findings show that different MAFs from T-cell clones may be useful to clarify molecular mechanisms of macrophage activation.
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PMID:Activation of macrophages by lymphokines from T-cell clones: evidence for different macrophage-activating factors. 639 5

Extracellular slime was isolated from 15 P. aeruginosa typing strains of different O-serotypes (immunotypes). The isolated slime, partially purified by ethanol precipitation, was later referred to as crude slime. Glycolipoprotein was obtained from crude slime and lipopolysaccharide (LPS) was obtained from acetone-dried microbial cells by the method of aqueous-phenol extraction. All these antigenic preparations were studied in the active mouse cross-protection tests: immunized mice were challenged with 7 strains of different immunotypes, strain No. 170 019 or toxigenic strain PA-103. In experiments on mice the slime of different P. aeruginosa serotypes (immunotypes) was found to stimulate immunity to intraperitoneal infection with P. aeruginosa, both homologous or heterologous in respect to their immunotype, including toxigenic strains. Slime glycoprotein also stimulated active cross-immunity in mice, but the level of this immunity was higher than that of immunity stimulated by crude slime. LPS showed mostly weak protective activity in experiments on mice.
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PMID:[Protective cross activity of the extracellular mucus of Pseudomonas aeruginosa]. 641 92


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