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

The effect of age on the mitogenic and antigenic responsiveness of B cells is examined in spleen cell cultures of CBA/N and (CBA/N X DBA/2) F1 mice. Spleen cells from young male F1 mice (4- to 6-wk old) show lower mitogenic responses to lipopolysaccharide, a lower frequency of sheep erythrocytes (SRBC)-reactive B-cell precursors, and a lower percentage of Ig-bearing cells than age-matched female F1 mice. The expression of all three functions were found to increase with the age of the F1 male mice. Whereas male F1 mice at 60 wk of age showed an equivalent percentage of Ig-bearing spleen cells and a similar mitogenic responsiveness to LPS when compared to adult female F1 mice, the frequency of SRBC-reactive B-cell precursors remained threefold lower. These findings reveal that there is a slower maturation of B cells in mice expressing the X-linked defect and suggests that the defect has differential effects on the mechanisms of antigen and mitogen activation of B cells.
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PMID:B-cell differentiation in the CBA/N mouse. I. Slower maturation of mitogen and antigen-responsive B cells in mice expressing an X-linked defect. 31 94

A marked reduction in the number of plaque-forming cells from spleens of mice infected with Schistosoma mansoni to sheep erythrocytes (SRBC) and lipopolysaccharide from Escherichia coli was observed. This reduction coincided with the late stages of the infection and was also observed in unisexual infection with male worms. Treatment of the animals with a schistosomicidal compound (oxamniquine) almost completely abolished the immunosuppression. The suppression could be induced by administration of 60 microgramg protein from worm membrane preparations (24 h before SRBC injection), but not by egg-extract injection. When the crude membrane preparation was injected 48 h before or 0 to 24 h after the SRBC challenge, the immunosuppression was not observed. Significant reduction of footpad swelling was also noted in infected mice when injected with SRBC.
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PMID:Immunosuppression mediated by adult worms in chronic schistosomiasis mansoni. 32 99

The antibody response to SRBC and E. coli 0127 lipopolysaccharide were determined in offspring from mice exposed in utero to diethylstilbestrol. The antibody response to SRBC, a T-cell dependent antigen, was similar in control and exposed animals. In contrast, the LPS antibody response was suppressed in treated females and enhanced in treated males. These studies indicated that in utero exposure to DES alters the humoral immune system to T-independent antigens.
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PMID:Alterations of the antibody response following in utero exposure to diethylstilbestrol. 36 5

The in vitro anti-SRBC response of several murine strains declined markedly with age in parallel with an increase in the activity of suppressor cells in the spleen and bone marrow which prevented early events during the induction of the immune response. These suppressor cells released soluble mediators and lacked the characteristics of mature T cells or macrophages. In addition the suppressor cell in the bone marrow could be removed on anti-Ig columns and fractions of old splenic suppressor cells sedimenting at 0.32 cm/h were greatly enriched in surface Ig bearing cells. Old immunodepressed mice did not lack potentially immunocompetent cells since the antibody response of old spleen cells could be restored by specifically activated T cells or lipopolysaccharide which act on B cells. These results suggest that a rise in the activity of non-T suppressor cells in the spleen and bone marrow may account, in part, for the depression in humoral immunity observed in aging mice.
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PMID:Immunological senescence. I. The role of suppressor cells. 36 7

Spleen cells from mice injected with 2 to 50 microgram bacterial lipopolysaccharide (LPS) have a reduced capacity to make an antibody response in vitro to trinitrophenylated sheep erythrocytes (TNP-SRBC) when tested 1 to 7 days later. Recovery is gradual, and these cells are full functional 2 weeks after in vivo LPS treatment. Unresponsiveness resides in the nonadherent splenic cell populations, and can be shown to have a suppressive cell component, which is irradiation sensitive and has somme characteristics of a thymus-derived lymphocyte (T cell). In addition, neither bone marrow-derived lymphocytes (B cells) nor T cells in the spleens of LPS-treated mice are functionally normal in their abilities to cooperate during an antibody response in vitro. LPS-B cells cooperated poorly with nylon wool-enriched T cells from normal mice but cooperated well with irradiated carrier-primed T cells or nylon wool-purified splenic T cells from carrier-primed mice. LPS-T cells have a reduced capacity to interact with normal B cells and appear to contain a suppressor cell component. These results indicate that the effects of exposure of immunocompetent cells to LPS are multifocal and can include suppression as well as stimulation of antibody formation.
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PMID:Modulation of immune response by bacterial lipopolysaccharide (LPS): multifocal effects of LPS-induced suppression of the primary antibody response to a T-dependent antigen. 36 44

Evaluation of Escherichia coli vaccines used in veterinary practice usually relates to antibody formation and neglects the essential characteristics of cell function leading to this end. This paper attempts to investigate the cellular responses to E coli O138 lipopolysaccharide (LPS) administered subcutaneously in a dose range of 1 microgram to 200 microgram. Rosette-forming cell responses in the draining lymph node varied from antigenic at 10 microgram to tolerogenic at 200 microgram. The tolerogenic dose also caused a marked mitogenic response as can be seen by a fourfold increase in total lymph node cells. Fractionation of normal or LPS-responding, or LPS-tolerised lymph node cells into B cell-rich and T cell-rich fractions was carried out and these were adoptively transferred simultaneously with an antigenic dose of sheep erythrocytes (SRBC) into syngeneic recipient mice. Suppressor activity of the anti-SRBC response was found after transfer of 1 X 10(6) normal B cell fractions, 1 X 10(6) tolerised B cell fractions and 1 X 10(6) tolerised T cell fractions. LPS-antigenically stimulated lymph node cell fractions had no suppressor effect but when given with Freund's complete adjuvant ensuing T cell-rich fractions produced immunosuppression in recipient mice. The significance of these findings is discussed in relation to polyclonal B cell activation, helper and suppressor T cells, and possible feedback mechanisms between interacting subpopulations of lymph node cells.
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PMID:In vivo studies on suppressor lymphocyte activity following administration of Escherichia coli O138 lipopolysaccharide. 36 76

Unfractionated spleen cells, B cells from normal mice, and nu/nu spleen cells respond to the addition of bacterial lipopolysaccharide (LPS) and T-cell-replacing factor (TRF) by production of plaque-forming cells (PFC) in excess of the number expected from the addition of LPS and TRF separately. This synergistic activity is dependent on the presence of the antigen, SRBC. Supernatants of both allogeneic spleen cell mixtures and spleen cells cultured with Con A are effective and synergize best at concentrations suboptimal for their ability to act as TRF alone. Culture supernatants of unstimulated normal or fractionated cell populations are ineffective. Synergy is not dependent on the presence of macrophages in the cultures. Purified LPS free from active contaminants, as well as commercially available LPS, show synergy with TRF. Synergy was seen when TRF was added at initiation of culture or 24 hr later. It is suggested that synergy is the equivalent of LPS adjuvant activity, that the role of T cells in LPS adjuvanticity is that of a conventional cooperating cell, and the LPS acts as an adjuvant by inducing B cells to become more sensitive to T cell helper factors.
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PMID:Synergy between T cell-replacing factor and bacterial lipopolysaccharides (LPS) in the primary antibody response in vitro: a model for lipopolysaccharide adjuvant action. 37 17

The effects of inhibitors of cell division on polyclonal stimulation induced either by bacterial lipopolysaccharide (LPS) or by a synthetic adjuvant, MDP, were compared, using different target cells. Doses of colchicine that prevented 3H-thymidine incorporation also prevented the induction of antibodies against TNP and against an altered self antigen: bromelain-treated mouse red blood cells (br-MRBC). Under identical conditions, incubation with cytosine arabinoside (CA) strongly prevented the induction of anti-TNP PFC and to a lesser degree anti-SRBC PFC. However, the number of anti br-MRBC PFC was unchanged even when a dose of CA which inhibits totally the incorporation of 3H-thymidine was used. Our findings indicate that the general term "polyclonal stimulation" may concern at least two different types of cell populations and therefore we strongly stress the importance of choosing similar targets in comparative experiments.
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PMID:Effect of cell division inhibitors on polyclonal activation can vary according to the target cell used. 39 5

Antibody response to a T-cell dependent antigen, sheep erythrocytes and to a B-cell mitogen, purified lipopolysaccharide (LPS), has been studied in mice kept on protein deficient (2 and 4 per cent casein) diets. The number of plaque-forming cells (PFC) to SRBC were 20-5 +/- 7-7 per million spleen cells in protein-deficient animals compared to 261-0 +/- 31-1 in parallel controls maintained on a protein rich diet (18 per cent casein). No difference was observed in number of PFC formed in controls and deficient animals to LPS, values were 161-4 +/- 19-7, 158-5 +/- 14-2, & 162-3 +/- 31-9 in control (18 per cent casein) and deficient groups (4 per cent and 2 per cent casein) respectively. The delayed hypersensitivity skin reaction to SRBC measured in foot pads was significantly lower in mice on 4 per cent casein diet compared to controls. These studies suggest that the effect of protein deficiency is primarily on T-cell function and not on the B-cell response;
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PMID:Depression of T-cell function and normality of B-cell response in protein calorie malnutrition. 40 30

Various subcellular bacterial fractions are known to enhance immune responses and serve as potent adjuvants. Muramyl dipeptide (MDP), a synthetic adjuvant mimicking a component of mycobacterial cell walls, enhances humoral immunity to soluble antigens and can increase macrophage cytotoxicity toward mastocytoma cells in vitro. In the present study MDP was found to enhance the hemolytic antibody plaque response of normal mouse spleen cells in vitro to SRBC at a level equal to or greater than that induced by Escherichia coli lipopolysaccharide. Furthermore, MDP was found to enhance the antibody response to SRBC nonspecifically in unimmunized spleen cell cultures, suggesting that similar to LPS the synthetic dipeptide may induce a generalized clonal expansion of committed lymphocytes and thus serve as a "polyclonal activator." MDP also enhanced the immune responsiveness of normal splenocytes to suboptimum concentrations of SRBC, indicating that this material may be useful in enhancing immunity in situations where there would normally be a poor immune response.
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PMID:Stimulation of an enhanced in vitro immune response by a synthetic adjuvant, muramyl dipeptide. 41 67


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