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

The suppression of contact hypersensitivity (CHS) after a single exposure to ultraviolet (UV) radiation provides an excellent model system with which to study both the activation and the mode of action of suppressor T cells. Suppression of CHS after UV radiation is mediated by hapten-specific suppressor T cells (UVTs). These cells have a broad range of activity: CHS and antibody production in vivo and the generation of cytolytic T lymphocytes (CTL) and T-cell proliferative responses in vitro are suppressed by UVTs. The present study is concerned with determining the target of UVTs. The UVTs could suppress the response to hapten-modified T-dependent antigens, such as trinitrophenyl (TNP)-modified sheep erythrocytes (TNP-SRBC) or TNP-conjugated bovine serum albumin (TNP-BSA), but had no suppressive effect on the response to a T-independent antigen, TNP-conjugated lipopolysaccharide (TNP-LPS). The UVTs also suppressed the generation of interleukin-2 (IL-2) in vitro. The suppression of CTL generation in vitro and CHS in vivo could be overcome by the addition of exogenous IL-2. These data suggest that UVTs suppress the immune response by affecting T-helper cell function.
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PMID:The effect of ultraviolet radiation-induced suppressor cells on T-cell activity. 295 84

Immunological effects of manganese chloride (MnCl2) were determined in male CD-1 mice injected (ip) daily with MnCl2 (0, 1, 3, or 10 mg/kg) for 4 wk. Liver and spleen weights increased in the 10-mg/kg MnCl2 treatment group. The weights of thymus, kidney, and adrenal glands were not affected by MnCl2 treatment. No significant differences in peripheral erythrocyte or leukocyte counts were observed; however, packed cell volumes decreased in the medium- and high-dose groups. Manganese treatment significantly increased the uptake of [3H]thymidine (3H-TdR) by cultured splenic cells. The lymphoproliferative responses to phytohemagglutinin (PHA) and concanavalin A (Con A) increased at all levels of MnCl2 exposure. No differences in the responses to lipopolysaccharide (LPS) were observed. Mixed lymphocyte responses increased significantly with exposure to 10 mg MnCl2/kg. Another immunological alteration induced by MnCl2 was a dose-dependent immunosuppressive effect on the development of antibody-forming cells. The production of anti-sheep red blood cell antibody (alpha-SRBC) nearly ceased following exposure to 10 mg MnCl2/kg. This effect was apparently reversible, as the number of plaque-forming cells in the 10-mg/kg treatment group increased after MnCl2 treatment had been halted for 2 wk. The alpha-SRBC titer also decreased significantly in the 10-mg/kg treatment group, corresponding to the reduction of antibody producing cells. MnCl2 treatment was immunomodulatory to the reduction of antibody producing cells. MnCl2 treatment was immunomodulatory in male CD-1 mice, as indicated by the increase in mitogen and mixed lymphocyte responses and decrease in antibody production.
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PMID:Alteration of humoral and cellular immunity in manganese chloride-treated mice. 295 31

Molecules of polysaccharide, lipopolysaccharide, and peptidoglycane from Pseudomonas aeruginosa were assayed as immunogens and immunomodifiers. The kinetics of humoral responses, phagocytic activity, splenic index variations, and immunomodulating ability of these molecules were studied. Their protective and immunomodifying effects were compared to those similarly produced by heat-killed bacteria suspensions. The influence of the nature and doses of these molecules as well as the intervals between their administration and the SRBC immunization were also studied. Results showed that higher IgM and IgG levels were produced by lower doses of lipopolysaccharide and peptidoglycane, respectively. Using these amphiphilic molecules at doses of 160 micrograms/mouse, a variable immunodepressive activity was observed. This dose-dependent effect which particularly altered the IgM synthesis, was also observed in phagocytic responses. The exopolysaccharide showed to be the most immunodepressive molecule, and this activity appeared to be dependent of dose and time of administration.
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PMID:Immunomodifying activity of some amphiphilic compounds from pathogenic Pseudomonas aeruginosa strains. 309 99

Recent reports suggest that the immunotoxicity of certain polycyclic aromatic hydrocarbons is associated with the Ah locus in mice. To test whether immunosuppression mediated by 7,12-dimethylbenz[a]anthracene (DMBA) is regulated by the Ah locus, several endpoints of immune function were measured in Ah-responsive B6C3F1 and Ah-nonresponsive DBA/2N and in Ah-congenic C57BL/6J (responsive B6-AhbAhd and nonresponsive B6-AhdAhd) mice dosed sc with up to 100 micrograms/g DMBA in corn oil. Some groups of B6C3F1 and DBA/2N mice were exposed to 100 micrograms/g benzo[a]pyrene (B(a)P) or 1 nmol 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for determination of hepatic microsomal monooxygenase activity. The body weights of all mice were unaffected by DMBA exposure, but thymus weights and spleen cellularity were decreased. Antibody plaque-forming cells (PFC) measured 4 days after iv sheep erythrocyte (SRBC) immunization were suppressed 99% in B6C3F1 and 96% in DBA/2 mice. Antibody PFC after in vitro immunization to SRBC were similarly suppressed 98% in both B6-AhbAhd and B6-AhdAhd Ah-congenic mice exposed to 100 micrograms/g DMBA. Responses to the T-cell mitogens concanavalin A and phytohemagglutinin were significantly suppressed in both B6C3F1 and DBA/2N strains, as was mitogenesis to bacterial lipopolysaccharide. The unidirectional mixed lymphocyte responses of the congenic strains were suppressed 76% in B6-AhbAhd and 85% in B6-AhdAhd, cytotoxic lymphocyte generation was suppressed 68% in B6-AhbAhd and 78% in B6-AhdAhd. The overall differences between immunosuppressive responses in splenocytes from B6-AhbAhd and B6-AhdAhd congenics were not significant. Induction of cytochrome P1-450, a marker of Ah responsiveness, was determined by 7-ethoxycoumarin O-deethylase monooxygenase activity in hepatic microsomes or splenocytes. This monooxygenase activity was not significantly increased in either B6C3F1 or DBA/2 mice exposed to DMBA, whereas B(a)P and TCDD exposure significantly induced enzyme activity in B6C3F1 hepatocytes. These data suggest that DMBA has an immunosuppressive action on murine splenocytes which is independent of the Ah locus and associated induction of cytochrome P1-450 xenobiotic-metabolizing enzymes.
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PMID:Immunosuppression following exposure to 7,12-dimethylbenz[a]anthracene (DMBA) in Ah-responsive and Ah-nonresponsive mice. 312 68

Murine alveolar macrophages (AM) have been shown to be inefficient at providing accessory function for initiation of the in vitro plaque-forming cell (PFC) response. In the present study AM, which were obtained either from untreated mice (resident AM) or mice injected i.v. with BCG (activated AM) potently suppressed the PFC response of spleen cells from animals previously primed with sheep erythrocytes (SRBC). Addition of AM at a concentration of 10% with respect to spleen cells resulted in greater than 90% suppression of the PFC response. In order to determine if inefficient antigen presentation was associated with AM-mediated suppression, the role of IL-1 and Ia antigen was studied. Addition of exogenous recombinant IL-1 (rIL-1) stimulated the PFC response in control cultures, but had no effect on AM-mediated suppression. Resident AM could be activated with lipopolysaccharide or antigen to produce significant levels of IL-1. Membrane-bound IL-1, thought to be important in the presentation of particulate antigens, was detected on glutaraldehyde-fixed resident AM and was significantly elevated in BCG-activated macrophages. The frequency of cell surface Ia antigen expression was low in resident AM (4%), but could be increased (35%) after in vivo activation with BCG. Recombinant interferon-gamma (IFN-gamma), known to enhance expression of Ia antigen and production of IL-1, had no effect on AM-mediated suppression when used either to pretreat AM, when present during the entire period of culture, or when injected into mice before culture initiation. Treatment with IFN-gamma, however, resulted in a slight increase in the expression of Ia antigen. These results indicate that the immunosuppressive activity of AM is neither related to a defect in IL-1 production or expression nor to a deficiency in Ia antigen expression and therefore can not be explained by the inefficient antigen-presenting function of alveolar macrophages.
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PMID:Relationship between ineffective antigen presentation by murine alveolar macrophages and their immunosuppressive function. 313 8

Adjuvant-activated Lyt-2 positive suppressor T cells (Ts) are able to inhibit the expression of IgM plaque-forming cells (PFC) during a primary in vitro response to sheep red blood cells. Under the same experimental conditions these suppressor T cells do not affect a secondary IgM PFC response against SRBC. Activated Ts cells were also found to suppress the spontaneous IgM secretion of cultured B cells as well as the IgM production of B cells stimulated by lipopolysaccharide or by supernatant from a T-helper-cell clone.
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PMID:Regulation of IgM expression by adjuvant activated splenic suppressor T cells. 316 23

Cyclophosphamide injections to mice following T cell mitogen (lectins from Lens culinaris and concanavalin A) were shown to suppress (20-40-fold) thymus-dependent response to SRBC. At the same time no damage-specific and polyclonal response to thymus-independent antigen and polyclonal activator of B cells--lipopolysaccharide--has been observed. Injections of lectin and cyclophosphamide to mice prevented the onset of DTH reaction to SRBC and induction of antigen-specific DTH suppressor cells. Thus, cyclophosphamide injection after T cell mitogen leads to T-cell anergy, with B-cell activity remaining unchanged.
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PMID:[T-cell immunodeficiency in mice receiving lectin and cyclophosphamide]. 326 Nov 77

Oxamisole is a T-cell immunorestorative agent when administered by the oral (p.o.) route. It has little or no effect on the IgM or IgG responses to the T-dependent antigen, sheep erythrocytes (SRBC), in normal mice but augments antibody production in immunodeficient animals. Unlike the response to SRBC, the humoral immunocompetence of both normal and immunosuppressed animals sensitized with the T-independent antigen, trinitrophenyl-lipopolysaccharide (TNP-LPS) was unaffected by oxamisole. Oxamisole restored cellular immunocompetence, as evidenced by an increase in the in vitro proliferative response of normal murine splenocytes to T-cell mitogens, while decreasing B-cell mitogenic responses. This indicates that oxamisole may selectively restore T-cell function. However, oxamisole did not significantly modify the classical T-cell-mediated delayed hypersensitivity responses to either the protein antigen methylated bovine serum albumin or to the contact-sensitizing antigen oxazolone. When assayed in vitro, oxamisole enhanced macrophage chemotactic function but not phagocytic function, suggesting a potential stimulation of the reticuloendothelial system. In vivo studies failed to demonstrate any consistent significant activation of murine macrophage function following oral dosing with oxamisole.
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PMID:The immunological profile of a new immunomodulatory agent, oxamisole. 326 41

Albino rats aged 7-8 weeks old purchased from the National Laboratory Animal Centre, Salaya, Nakhon Pathom, were found to be a good animal model for the study on immunogenicity of V. cholerae antigens. Seventy-two rats were fasted for 15 hours before feeding each one with 1 ml of 5% NaHCO3 to reduce gastric acidity prior to immunization. They were divided into 9 groups of 8 rats and immunized orally with 2 ml, each, of the V. cholerae antigens dissolved or suspended in Cassamino acid as follows: group 1 (control): Cassamino acid (Ca) alone; group 2 (control): 2.5% formalinized sheep red blood cells (F-SRBC); group 3: 1,000 micrograms of lipopolysaccharide (LPS); group 4: 100 micrograms of procholeragenoid (P); group 5: 80 haemagglutinating units of cell-bound haemagglutinin (CHA) adsorbed onto the surface of F-SRBC (CH-SRBC); group 6: 500 micrograms of LPS + 50 micrograms of P; group 7: CH-SRBC + 50 micrograms of P; group 8: combined vaccine formula 1 consisted of 500 micrograms of LPS, CH-SRBC and 50 micrograms of P and group 9: combined vaccine formula 2 consisted of 1,000 micrograms of LPS, CH-SRBC and 100 micrograms of P. The immunization was repeated once more 14 days later. Five days, thereafter, the rats were killed and their jejuni were removed for cryostat sectioning. Antibody producing cells against LPS (anti-LPS cells), P (anti-CT cells) and CHA (anti-CHA cells) in the intestinal lamina propria were enumerated by double antibody sandwich method of immunofluorescence using pure LPS, cholera toxin (CT) and pure CHA as the antigens in the assay, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Oral vaccine against cholera prepared from Vibrio cholerae antigen(s). 331 33

We have investigated whether bacterial lipopolysaccharide (LPS) influences immune responses to dietary protein antigens in experimental animals. Simultaneous intravenous administration of LPS to normal mice fed ovalbumin (OVA) prevented the induction of tolerance for serum IgG antibody responses but did not alter the tolerance of systemic delayed-type hypersensitivity (DTH). In addition, exogenous LPS did not enhance the ability of spleen accessory cells to present OVA to primed T cells. LPS-unresponsive C3H/HeJ mice developed full tolerance of both humoral and cell-mediated immunity after feeding a range of doses of OVA that was equal in degree and persistence to that seen in normal, congenic C3H/HeOla mice and also had normal antigen-presenting cell (APC) activity for OVA. In contrast, C3H/HeJ mice were primed by feeding SRBC instead of developing the systemic tolerance found in normal C3H mice. Our results indicate the complexity of mechanisms that may regulate systemic immunity to orally administered antigens of different forms. Nevertheless, LPS does not modulate DTH responses to fed OVA and does not enhance APC activity, and we conclude that bacterial LPS may be unable to influence hypersensitivity to dietary proteins in man.
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PMID:Divergent effects of bacterial lipopolysaccharide on immunity to orally administered protein and particulate antigens in mice. 348 67


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