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

Mouse thymus cells are essentially unresponsive to lipopolysaccharide (LPS) stimulation. However, when cultured with minimally mitogenic levels of concanavalin A or submitogenic ratios of mitomycin-treated allogeneic spleen cells, in combination with LPS, they demonstrate levels of DNA synthesis de novo or greater than those induced by the T cell mitogen alone. Dose-response kinetics were characteristic of LPS. The subpopulation containing the LPS responsive cells was of low net buoyant density. Neither phytohemagglutinin nor pokeweed mitogen acted synergistically with LPS in this model to trigger thymus cells. The data suggest that LPS triggering may involve interaction with a T cell subpopulation.
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PMID:T mitogens trigger LPS responsiveness in mouse thymus cells. 12 88

The formation of anti-DNA antibodies appears to be under a genetic control similar to that regulating the immune response to complex antigenic compounds. The ability to develop a high immune response to DNA seems to be predominantly dependent on the nature of the B-cell population whereas a major role of the T-cell suppressor population is not evident in this response. The immune response to DNA does not necessarily need the presence of thymus-derived lymphocytes, but in some cases T-cells may exert a helper effect. The development of anti-DNA antibody response may be triggered by various factors: viral, bacterial or parasitic agents, tissue destruction or some drugs. A mechanism that may play an important role is the "nonspecific" triggering of anti-DNA antibodies by substances that, like bacterial lipopolysaccharides, exert a potent stimulatory effect on B-cells and simultaneously induce a release of DNA in extracellular fluids. In lupus diseases as well as in mice injected with lipopolysaccharide, pathogenic effects of anti-DNA antibodies appear to be closely related to the formation of DNA-anti-DNA complexes. The demonstration that injections of lipopolysaccharide lead to the localization of DNA-anti-DNA complexes in kidney glomeruli stressed the possible importance of stimuli responsible for a release of DNA in circulating blood in the expression of the pathogenic effects of anti-DNA antibodies.
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PMID:Genesis and pathogenicity of anti-DNA antibodies. 13 82

The precise relationship between the stem cells for the lymphoid system and those for the blood-forming system is unclear. While it is generally assumed that the hemopoietic stem cell, the spleen colony-forming unit (CFU-S), is also the stem cell for the lymphoid system, there is little evidence for this hypothesis. To investigate the stem cells in these two systems, we irradiated bone marrow cells to induce unique chromosome aberrations in the stem cell population and injected them at limiting dilution into stem cell-deficient recipients. Several months (between 3 and 11) were allowed for the injected cells to repopulate the hemopoietic system. At that time, the bone marrow, spleen, and thymus were examined for a high frequency of cells having the same unique chromosome aberration. The presence of such markers shows that the marker was induced in a cell with extensive proliferative capacity, i.e., a stem cell. In addition, the splenic lymphocytes were stimulated with phytohemagglutinin (PHA) or lipopolysaccharide (LPS) to search for unique chromosomes in dividing T and B cells, respectively. Finally, bone marrow cells were injected into secondary irradiated recipients to determine if the marker occurred in CFU-S and to determine whether or not the same tissue distributions of marked cells could be propogated by bone marrow cells in a second recipient. After examination of 28 primary recipients, it was possible to identify three unique patterns of stem cell regeneration. In one set of mice, a unique chromosome marker was observed in CFU-S and in PHA- and LPS-stimulated cultures. These mice provide direct evidence for a pluripotent stem cell in bone marrow. In addition, two restricted stem cells were identified by this analysis. In three recipients, abnormal karyotypes were found only in myeloid cells and not in B and T lymphocytes. These mice presumably received a marked stem cell restricted to differentiate only into myeloid progeny. In three other recipients, chromosome aberrations were found only in PHA-stimulated cells; CFU-S and cells from LPS cultures did not have cells with the unique chromosome. This pattern suggests that bone marrow contains cells committed to differentiation only into T lymphocytes. For each of the three types of stem cells, secondary recipients had the same cellular distribution of marked cells as the primary recipients. This observation provides further evidence that unique markers can be induced in both pluripotent and restricted stem cells.
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PMID:The identification in adult bone marrow of pluripotent and restricted stem cells of the myeloid and lymphoid systems. 14 Sep 17

The blastogenic responses of lymphocytes from chemically-induced (streptozotocin) and genetically-diabetic C57B1/6J (ob/ob) obese mice were assessed using mixed-lymphocyte cultures (MLC) and mitogens selective for thymus-derived (T cell) and bone marrow-derived (B cell) lymphocytes. Splenic lymphocytes from obese and normal C57B1/6 mice exhibited similar responses to the nonspecific T and B cell mitogens, Concanavalin A (Con A) and E. coli lipopolysaccharide (LPS), respectively. A small (25%) depression of the blastogenic response in MLC was observed for lymphocytes from obese mice. The generation of cytotoxic T cells in vitro in response to trinitrobenzene sulphonic acid (TNP)-modified syngeneic spleen cells was the same for normal and obese mice. In contrast, splenic lymphocytes from 7-14 day streptozotocin-diabetic mice had lower (56-60%) proliferative responses in MLC. The generation of cytotoxic effector cells in vitro was lower for spleen cells for spleen cells from 22-day streptozotocin mice, although blastogenic responses in MLC were not depressed. The insulin-deficient streptozotocin mice appear to have a depression of some thymus-derived cell functions that may be associated with streptozotocin rather than the diabetic state. Direct immunosuppressive effects of streptozotocin are indicated by the marked decrease in the number of lymphocytes in the thymus, lymph nodes, and spleen.
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PMID:Immune responses of diabetic animals. Comparison of genetically obese and streptozotocin-diabetic mice. 14 82

Mouse interferon preparations significantly suppress the in vivo antibody response to sheep red blood cells (SRBC), a thymus-dependent antigen, and to Salmonella typhimurium lipopolysaccharide (LPS), a thymus-independent antigen. It is also possible to effect the late responses of antigen sensitive "memory" cells observed during secondary immunization by administration of interferon prior to primary immunization. The immunosuppressive activity of interferon was time- and dose-dependent. Maximum suppression was produced when animals were given 1.5 times 10-5 units of interferon between 4 and 48 hr before antigenic stimulation. These findings suggested that interferon affects some early event(s) in the process of antibody synthesis which might be related to the general inhibitory effect of interferon on rapidly dividing cells and viral m-RNA translation. In addition, the use of nonadherent spleen cell cultures from interferon-treated mice, immunized in vitro with a thymus-independent antigen, indicated that in this situation the inhibitory effect of interferon was due to an action on B lymphocytes. A variety of soluble "suppressive" factors are secreted by T cells as a consequence of activation by mitogens or specific antigens in vitro. Since T cells are recognized as one of the sources of interferon, it is suggested that interferon should be investigated as a suppressor T cell-produced lymphokine which can regulate B cell expression.
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PMID:Mechanism of the suppressive effect of interferon on antibody synthesis in vivo. 16 63

We reported previously in vitro induction of endogenous C-type viruses from normal mouse spleen cells by lipopolysaccharide (LPS) as well as by combination treatment with concanabalin A and 5-bromo-2'-deoxyuridine (Con A/BrdU). To identify the cell types sensitive to virus induction and to study the relationship of mitogenicity to virus induction we have compared T cell populations (BALB/c thymus cells and cortisone-resistant thymus cells), B cell populations (nu/nu spleen cells and lymph node cells), adherent BALB/c peritoneal cells and mixed populations (BALB/c spleen cells, macrophage-depleted BALB/c spleen cells, and lymph node cells). LPS-induction occurred only in B cell-containing populations. In contrast, induction by Con A/BrdU depended on the presence of both T and B cells. In both instances, neither macrophages nor hemopoietic cells appeared to be a major source of virus. Treatment with anti-Ig serum and complement reduced virus induction by LPS/BrdU but not by Con A/BrdU suggesting that different cell populations produce virus after stimulation with these two different mitogens.
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PMID:Mitogen induction of murine C-type viruses. I. Analysis of lymphoid cell subpopulations. 17 74

Polymyxin B, which is a basic polypeptide produced by various strains of Bacillus Polymyxa, has previously been shown to prevent the lethal effect of LPS and to neutralize the Schwartzmann reaction. In this study we have investigated the interactions between polymyxin B and lipopolysaccharide (LPS) and hapten LPS conjugates. Polymyxin B was found to suppress mitogenicity of LPS and also to inhibit immunogenicity of the hapten conjugate 4-hydroxy-3,5-dinitrophenacetyl (NNP)-LPS. Inhibition was not due to interference with the expression of NNP determinants nor to cross-reactivity between PB and the hapten. Since mitogenicity and immunogenicity decreased in parallel, we conclude that B-cell activation in specific thymus independent responses does not take place in the absence of a nonspecific (non-Ig-mediated) signal.
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PMID:Association between mitogenicity and immunogenicity of 4-hydroxy-3,5-dinitrophenacetyl-lipopolysaccharide, a T-independent antigen. 17 23

Murine lymphoid cells were infected in vitro with WN 1802 B, a naturally occurring murine leukemia virus isolated from the spleen of an 18-month-old BALB/c mouse. Normal spleen and bone marrow cells were more susceptible to infection than were cells prepared from thymus and lymph node. Spleen cells from athymic nu/nu mice also could be readily infected with virus. Permissive cells did not ingest iron readily infected with virus. Permissive cells did not ingest iron filings and did not adhere to plastic. Exogenous replication of murine leukemia virus was enhanced in spleen and lymph node cells treated with lipopolysaccharide, a bone marrow-derived lymphocyte mitogen. Conversely, cells treated with the thymus-derived lymphocyte cell mitogens, phytohemagglutinin and concanavalin A, were less capable of supporting murine leukemia virus replication. These studies suggest that the natural host for WN 1802 B is the bone marrow-derived lymphocyte.
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PMID:Replication of murine leukemia virus in bone marrow-derived lymphocytes. 18 25

Polymyxins are known to be inhibitors of certain polyclonal B cell activators such as lipopolysaccharide and dextransulphate. However, increased specific responses to hapten-coupled mitogens have been reported after the addition of polymyxins to superoptimal conjugate doses. In this paper we have studied the effect of polymyxin B on superoptimal polyclonal doses of lipopolysaccharide. Results similar to those reported for hapten-lipopolysaccharide conjugates were obtained. Polymyxin B was also found to exert adjuvant properties for a primary immune response to sheep erythrocytes and to be a thymus-independent antigen.
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PMID:B-cell activating properties of polymyxin B. 20 83

The effects of thymosin and lipopolysaccharide (LPS) on cyclic AMP levels in lymphocytes were evaluated using three independent assays which included adenine prelabeling, protein kinase binding, and radioimmunoassay. All three assays proved to be both sensitive and accurate in assessing relative changes in lymphocytes after incubation in vitro with various agents. The assays confirmed that basal and stimulated levels of cyclic AMP depended on the origin of the lymphocyte population. Each of the three techniques demonstrated that pyrogen-free bovine thymosin fraction 5 did not elevate thymocyte cAMP levels. In contrast, it was found that lipopolysaccharide (lps) significantly elevated cAMP levels in both spleen and thymus lymphocytes. These studies indicate that assays for measuring the activity of thymic extracts in which the intracellular levels of cyclic nucleotides are a criterion for activity are only valid if the preparations are not contaminated with endotoxins.
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PMID:Effect of thymosin and lipopolysaccharide on murine lymphocyte cyclic AMP. 20 27


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