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

Plaque-forming cell responses against sheep erythrocytes, Escherichia coli lipopolysaccharide, pneumococcal polysaccharide, and polyvinylpyrrolidone were examined in mice infected with lymphocytic choriomeningitis virus. A 92 to 96 percent reduction of the thymus-dependent anti-sheep erythrocyte responses was observed 2 to 4 weeks after infection. However, the thymus-independent responses against the three other antigens were close to normal at all stages of the infetion. Studies on allograft immunity of infected C3H mice against DBA/2 mastocytoma cells revealed a severe suppression of the T cell-mediated cytotoxic response which was temporally related to the impaired humoral responsiveness against sheep erythrocytes. The capacity of spleen cells from infected mice to restore immune responsiveness of lethally irradiated recipients against sheep erythrocytes was significantly reduced. The adoptive responses, however, were clearly improved when normal thymus cells were added to the inferior spleen cells. Moreover, it appeared that the spleen cells from immunosuppressed donor mice could not confer suppression to normal lymphoid cells. The presented findings are consistent with the assumption that a numeric deficiency of T cells, or cells belonging to some T cell subpopulation, is the primary cause of lymphocytic choriomeningitis virus-induced immunosuppression.
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PMID:T lymphocyte function as the principal target of lymphocytic choriomeningitis virus-induced immunosuppression. 23 88

When thymus cells which are unresponsive to LPS are combined with numbers of peripheral lymphoid cells giving minimal responses to LPS, synergistic incorporation of [3H]thymidine occurs. Synergy requires that both components proliferate, but most of the augmented response is the result of peripheral cell proliferation. The thymus cell is a T cell of variable density, low in thy-1.2 antigen, not concanavalin A responsive, present in the major thymus subpopulation, and may be from lipopolysaccharide (LPS)-unresponsive strains. The peripheral cell is sensitive to anti-IgG or IgM plus complement (C'), resistant to anti-Thy-1.2 and C', exhibits adherence properties of B lymphocytes, and must be from LPS-responsive strains. Synergistic responses depend on critical thymus/peripheral cell ratios, inhibition occurring at high peripheral cell numbers. The data provide evidence that B-cell proliferative responses to LPS may be regulated by a subclass of thymus T cells.
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PMID:Regulation of B-cell proliferative responses to lipopolysaccharide by a subclass of thymus T cells. 30 Jul 82

The functional changes in splenic lymphoid populations from mice infected with T. brucei strain S42 were studied throughout the 3 weeks of infection. Within a week of infection, proliferation of B and T cells profoundly increased as shown by 3H-labelled thymidine incorporation and fluorescent staining of surface Ig; the spleen cells secreted high levels of both IgM and IgG immediately cells were put into culture; but with progressing infection this Ig production declined. The early effect on T cells was reflected by lack of responsiveness to PHA. B-cell potential was studied in low-density cultures treated with lipopolysaccharide (E. coli). Normal spleen cells proliferate extensively in these cultures with subsequent secretion of IgG as well as IgM. The ability to proliferate and produce Ig in response to LPS was severely depressed by day 7 and almost totally absent by day 12 of infection. Removal of T cells from the spleen cells obtained early in infection partly restored the response to LPS but as the infection neared its fatal end, B-cell potential appeared to become exhausted. Macrophages obtained from infected mice even early in infection profoundly depressed the ability of normal spleen cells to proliferate and secrete immunoglobulin in LPS cultures. The general immunodepressing effect of trypanosomes can be attributed to clonal exhaustion of B-cell potential caused by an undefined blastogenic stimulus from the parasites which may operate at least in part by the generation of suppressive T cells and macrophages.
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PMID:Suppressor cells and loss of B-cell potential in mice infected with Trypanosoma brucei. 30 69

Endotoxin (lipopolysaccharide, LPS) has been found to act on all three cell types of the immune system, thymus-derived (T-) cells, bone marrow-derived (B-) cells, and macrophages. LPS is mitogenic for B-lymphocytes and activates them to release a chemotactic lymphokine. Macrophage activation appears to be mediated by macrophage-activating factor, another lymphokine released from B-cells. In addition, LPS acts synergistically with phytohemagglutinin to initiate division of purified T-lymphocytes. All these phenomena are mediated by the lipid A moiety of LPS. The role of lymphoid cells in mediating the lethal effects of LPS have also been investigated. The adoptive transfer of spleen cells from LPS-responsive mice (C3H/HeN) to LPS-resistant but histocompatible mice (C3H/HeJ) rendered the LPS-resistant mice significantly more susceptible to LPS-induced lethality. These findings suggest that spleen cells play an essential role in mediating the lethal effects of LPS in vivo.
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PMID:Action of endotoxin on lymphoid cells. 30 90

A functional subpopulation of murine B lymphocytes proliferate in semisolid agar culture in the presence of 2-mercaptoethanol to form colonies. The effects of diffusible macrophage-derived factors on this focal proliferation was investigated using a two-layer culture system which prevented macrophage-lymphocyte contact and permitted B-cell activation to be critically assessed under conditions of extremely low cell densities. Adherent peritoneal macrophages incorporated within underlayers of spleen or lymph node cell cultures potentiated both the number and size of developing B-cell colonies. These effects were most striking when low numbers of spleen or lymph node cells, or macrophage- depleted lymphoid cell suspensions were used. Thus, macrophage-depleted lymph node ceils gave rise to virtually no colonies, but colony-forming ability was restored by the presence of an optimal number of macrophages. When the number of macrophages exceeded that required for optimal stimulation, colony formation was suppressed; an effect which was largely prevented by indomethacin, an inhibitor of prostaglandin synthesis. Under these conditions, stimulation and inhibition of B-cell activation by macrophages could be dissociated, indicating that each signal is selectively controlled by individual molecules elaborated by the macrophage. With an appropriate number of macrophages required for B-cell activation, and sufficient indomethacin to inhibit the accumulation of macrophage-derived prostaglandin, B-lymphocyte clonal proliferation was a linear function of the number of B cells placed in culture. In the absence of macrophages, B-cell colony formation was potentiated by both lipopolysaccharide and intact sheep erythrocytes through a mechanism different from that of the macrophage-derived stimulatory factor. In addition to their direct stimulatory effect on B-cell proliferation, lipopolysaccharide and sheep erythrocytes were each capable of modulating the production and/or release of B-cell stimulatory and inhibitory factors by the macrophage. Parallel studies of conventional mitogen- stimulated lymphocyte cultures did not show a requirement for macrophages and confirm that the semisolid assay is uniquely suited to studies on the regulatory role of the macrophage in B-cell activation.
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PMID:Regulation of B-lymphocyte clonal proliferation by stimulatory and inhibitory macrophage-derived factors. 30 81

Nonirradiated B-lymphocyte-deficient CBA/N mice given T6T6 chromosome-marked normal CBA/CaHN spleen cells became lymphoid chimeras exhibiting donor-type mitoses. Normal CBA/CaHN recipients did not exhibit significant numbers of donor-type mitoses. The lymphoid cell chimerism in the CBA/N host appeared in spleen, lymph nodes, and Peyer's patches, but not in marrow or thymus. Stimulation of CBA/N-recipient spleen cells in vitro suggested that the chimerism involved donor T6T6 cells which were responsive to the B-lymphocyte mitogen, lipopolysaccharide, but not to the T-lymphocyte mitogen, phytohemagglutinin. These data indicate that stable, long-term chimerism of a specific class of lymphocytes is possible in nonirradiated, B-lymphocyte-deficient CBA/N mice.
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PMID:Induction of partial chimerism in nonirradiated B-lymphocyte-deficient CBA/N mice. 30 63

In studies reported here, the polyclonal activator lipopolysaccharide was used to stimulate the synthesis and secretion of IgM, IgA, and IgG in cultures of mouse lymphoid cells. The total immunoglobulin of each class which resulted was measured by specific double-antibody radioimmunoassays. The effect of Con A-activated T cells from various tissues on such immunoglobulin synthesis was then assessed. Variations in regulatory T-cell activity among the various lymphoid tissues for IgA but not for IgM or IgG was observed. In particular, Peyer's patches T cells were found to contain a high level of IgA T-cell helper activity compared to that of spleen or peripheral lymph node. The independent variation of T-cell regulatory activity for IgA as compared to that for IgM and IgG among the different tissues is most consistent with there being a separate subset of T cells specifically regulating IgA. The significance of these findings for the understanding of the secretory immune system is discussed.
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PMID:T-cell regulation of murine IgA synthesis. 31 11

When bacterial lipopolysaccharide, a B-cell mitogen, was injected intraperitoneally into mice, the rate of deoxyribonucleic acid synthesis and the number of antibody-secreting cells in the spleen increased simultaneously, reaching a maximum in 3 days. The rate of ribonucleic acid synthesis also increased during this period, and this was found to be due to activation of alpha-amanitin-sensitive transcription in lymphoid cells of the spleen. The factors stimulating ribonucleic acid polymerase II in the spleens of normal mice and those treated with lipopolysaccharide were compared, and an additional factor besides that present in normal spleens was found in the spleen of lipopolysaccharide-treated mice.
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PMID:Bacterial lipopolysaccharide induction of a mouse spleen factor stimulating ribonucleic acid polymerase II. 32 12

The effect of phytohaemagglutinin, lipopolysaccharide, lipid A and streptococcal erythrogenic toxin on the expression of surface immunoglobulins on nerborn piglet spleen lymphocytes was studied, using iodinated anti-pig Ig, L-, mu- or gamma-antisera. It has been concluded that only IgM is the surface immunoglobulin on non-stimulated as well as LPS-stimulated piglet lymphoid cells. An increase in the numberof labelled cells was observed after cultivation of piglet spleen cells with all the mitogens tested.
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PMID:Surface immunoglobulins on stimulated lymphocytes. 32 17

Twenty rabbits were each injected with 100 microgram of lipopolysaccharide from Escherichia coli 055 at weekly intervals for up to 15 months. The antisera showed an immunologic cross-reactivity with rabbit kidney glycoprotein. A macroscopic nephropathy was present in 14 of the 17 rabbits in which the kidneys were examined. All the rabbits showed extensive histologic lesions involving all the structures of the kidney: organized thrombosis of the arteries, extensive areas of infarction, glomerular atrophy, tubular necrosis and proliferation of young connective tissue. A marked infiltration with lymphoid cells and some plasmacytes was present. The immunologic character of this nephropathy and the immunopathogenic mechanism involved in its pathogenesis are discussed.
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PMID:Experimental nephropathy induced in the rabbit by immunization with a lipopolysaccharide from Escherichia coli. 35 4


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