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

The expression of cytocidal activity is induced by the sequential interaction of macrophages with a priming stimulus, such as interferon (IFN)alpha, -beta, or -gamma, and a triggering stimulus, such as poly(I.C) or lipopolysaccharide. However, most triggering stimuli are also capable of inducing IFN expression. This suggested to us the possibility that in addition to its role in initially priming macrophages for cytocidal activity, IFN may also be expressed during the triggering stage where it may potentially contribute to the regulation of cytocidal activity. We have explored this question by (i) attempting to dissociate IFN-inducing activity from triggering activity with a variety of structurally related and charge-related polyanions; (ii) determining if macrophages express IFN during the triggering stage; and (iii) questioning if IFN produced during the triggering stage contributes to the regulation of cytocidal activation. Exposure of unprimed macrophages to a triggering concentration of poly(I.C) alone failed to induce IFN beta expression. However, exposure of IFN beta-primed cells to poly(I.C) dramatically increased the expression of IFN beta mRNA. Priming with IFN gamma was likewise found to increase the expression of IFN beta mRNA in response to a triggering concentration of polyribonucleotides. Three approaches were adopted to ascertain if the increased expression of IFN beta contributed to cytocidal activation. First, macrophages derived from strains of mice which differ in their susceptibility to IFN induction by poly(I.C) were primed with IFN beta, washed, and triggered with poly(I.C). Under these conditions, macrophages derived from stain B10.A(2R), which are hyporesponsive to poly(I.C) in terms of IFN induction, also showed a diminished capacity to express Bf, a marker of cytocidal activation. Second, exposure of IFN-primed macrophages to poly(I.C) in the presence of anti-IFN alpha/beta antibody was found to reduce substantially the synthesis of NO2/NO3, an alternative marker of macrophage cytocidal activation. Third, exposure of IFN-primed macrophages to the calcium ionophores ionomycin or A23187, which do not induce the production of IFN beta during triggering, led to an abbreviated expression of Bf compared with stimuli that induce IFN beta expression such as poly(I.C). However, the capacity to synthesize Bf in response to A23187 was partially reconstituted when macrophages were triggered with the ionophore in the continuous presence of IFN beta. Collectively, these data show that IFN beta is expressed during the triggering stage of macrophage cytocidal activation and suggest that it plays an important and previously unsuspected role in the expression of this state.
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PMID:Expression of interferon-beta during the triggering phase of macrophage cytocidal activation. Evidence for an autocrine/paracrine role in the regulation of this state. 176 73

The present study has examined a functional role of Ia molecules expressed on murine B cells in polyclonal B cell differentiation induced by lipopolysaccharide (LPS). Reverse, IgM PFC responses of unprimed B cells induced by LPS in the apparent absence of T cells and adherent accessory cells were markedly inhibited in a haplotype-specific manner by Fab monomer fragment of anti-class II (Ia) but not anti-class I MHC monoclonal antibody (mAb). However, the degree of inhibition of LPS responses of H-2-heterozygous F1 B cells expressing both parental I-A products by either one of anti-I-A mAb was at best half that of the parental B cells. Interestingly, when (B10 x B10.-BR)F1 (H-2b/k) B cells were fractionated into adherent and nonadherent populations by their ability to bind to parental B10 B cell monolayers, LPS responses of F1 B cells adherent to and nonadherent to the B10 B cell monolayers were selectively inhibited by anti-I-Ab and anti-I-Ak mAb, respectively. These results suggest that LPS-responsive F1 B cells comprise at least two separate populations with restriction specificity for only one of the parental I-A products expressed on B cells. In addition, it was demonstrated that the I-A-restriction specificity of LPS-responsive B cells is "plastic" and determined by H-2-genotype of bone marrow cells present during B cell ontogeny but not by that of radiation-resistant host elements. Namely, the LPS responses of B10-derived B cells from (B10 + B10.BR) (H-2b x H - 2k)F1 radiation bone marrow chimeras but not from B10 (H-2b x H-2k)F1 chimeras became sensitive to the inhibition of anti-I-Ak mAb in the presence of mitomycin C-treated I-Ak-positive B cells, supporting a notion of receptor-Ia molecules interactions rather than like-like interactions. Thus, the present results provide evidence indicating that B-B cell interaction via recognition of self-I-A products is a crucial event in the polyclonal B cell differentiation induced by LPS.
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PMID:Involvement of I-A-restricted B-B cell interaction in the polyclonal B cell differentiation induced by lipopolysaccharide. 232 98

In vitro IgE synthesis by lymphoid cells was studied during the course of infection of mice with Nippostrongylus brasiliensis. The studies involved inbred strains of mice which had been shown to be high IgE responders (A.CA, B10.M), or non-responders (Balb/c, B10.D2) to parasite antigen. In addition, F1 hybrids of low and high responders and irradiated non-responders were studied. Infection with N. brasiliensis led to an increase in IgE synthesis in vitro which was most pronounced during reinfection of mice. Addition of mitogens e.g. pokeweed mitogen (PWM), lipopolysaccharide (LPS), concanavalin A (ConA) to the cultures induced enhancement, suppression or had no effect on IgE synthesis. Addition of N. brasiliensis homogenate or worm culture supernatant led to a fluctuating pattern of IgE synthesis. No correlation was found between lymphocyte proliferative response to mitogen and worm antigens and IgE synthesis. Our data suggest, that PWM is more likely to enhance IgE synthesis in vitro than LPS or ConA. An enhancement is more easily observed with the cells of non-infected animals or during the early phase of infection or reinfection. The mitogen-induced increase in IgE synthesis did not exceed the values obtained during infection or reinfection.
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PMID:IgE synthesis in vitro during infection of mice with the nematode Nippostrongylus brasiliensis: effects of mitogens and antigens. 241 41

The effects of six gastrointestinal regulatory peptides (beta-endorphin, substance P, metenkephalin, vasoactive intestinal peptide, bombesin, and somatostatin) on mouse lymphocytes stimulated with concanavalin A, lipopolysaccharide, phytohemagglutinin, or alloantigens were evaluated. Lymphocytes were stimulated in vitro and the influences of exogenously adding varying concentrations of neuropeptides (10(-6)-10(-11) M) on the incorporation of [methyl-3H-]thymidine were determined. The roles of cell density and antigen concentration on neuropeptide induced immunomodulation were also assessed. We observed that vasoactive intestinal peptide (VIP) would significantly inhibit the response of B10 lymphocytes to concanavalin A (54%) and phytohemagglutinin (56%) but not to lipopolysaccharide (16%). The VIP-induced inhibition was progressively diminished as the neuropeptide concentration was reduced to 10(-11) M. By 24 hr after stimulation the lymph node cells were refractory to the inhibitory effects of VIP. In addition, VIP would not inhibit B10 lymph node cells from responding to B10. K spleen cells in mixed, one-way lymphocyte cultures. The other five peptides did not influence the in vitro responses. The potential role of neuropeptides in the pathophysiology of immunologic-based disorders is discussed.
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PMID:Gastrointestinal regulatory peptides modulate in vitro immune reactions of mouse lymphoid cells. 242 53

The Sgp-1c trait is associated with H-2s and relates to the small content of serum gp70 as well as the lack of serum gp70 responsiveness to lipopolysaccharide (LPS). Northern hybridization of RNA from B10.S liver and its hybrid with NZB showed that the suppression of gp70 in Sgp-1c carrying mice can be regulated at the transcriptional level. However, the inheritance of this trait shows the complicated manner of segregation in certain crosses. All (B10.S x NZB) F1 hybrid mice and F1 x B10.S back-cross mice had low amounts of serum gp70 and did not respond to LPS with increased levels of serum gp70. In contrast, F1 x NZB back-cross progeny varied widely in serum gp70 levels. The serum gp70 levels of most F1 x NZB back-cross mice was increased by LPS, although the range of increases was broad. These results indicate that the Sgp-1c alone is not sufficient to lower serum gp70 levels, unless B10 background is present. The expression of Sgp-1 system, which is linked with the H-2 region, requires non-H-2-linked genes.
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PMID:Murine leukaemia virus gene product as an acute phase protein: complete suppression of serum gp70 synthesis in hepatocytes of B10.S mice. 248 47

We have developed a method for enumerating the frequency of Ig isotype switching in clones of B cells. The method adapts Poisson statistics to analyze the distribution of amounts of switched isotype produced by multiple subclones of cells and thus enables one to estimate the probability that a single cell will switch isotype in one cell generation. We have applied this method to determine the spontaneous switch frequency of two Ly-1+ B cell lymphomas of B10-H-2aH-4bp/Wts mice. Both CH12.LX and CH27.LX switch from IgM to IgA at very high frequencies (1 - 5 x 10(-3) switch events per cell division) and from IgM to IgG at low but detectable frequencies (10(-4) - 10(-5) switch events per cell division). Cloned IgG variants of CH12.LX switch to IgA at the same frequency as the IgM-producing cells. Bacterial lipopolysaccharide has a strong inhibitory effect on isotype switching by CH12.LX. Possible explanations for the observed preference for switching to IgA are discussed.
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PMID:Ig isotype switching in B lymphocytes. A method for estimating isotype switch frequency in cloned B cell lymphomas. 248 41

Membrane proteins from murine lymphoblasts enriched by the Triton-X114 procedure were analysed by 2-dimensional gel electrophoresis to reveal proteins differentially expressed in mitogen-reactive subpopulations of B cells. The protein patterns from C57BL/6 normal and nude mice and from the B10.Sc.Cr LPS-non-responder strain, activated with lipopolysaccharide (LPS) or an analogue of lipoprotein, were virtually identical when run under strictly parallel conditions. These experiments raise the question as to whether mitogen receptors, serologically and functionally found to be membrane-bound, do exist as membrane proteins.
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PMID:The membrane protein compositions of lipopolysaccharide- or lipoprotein-activated B lymphoblasts from C57BL LPS-responder and non-responder mice are qualitatively indistinguishable. 259 80

Natural suppressor (NS) cells are capable of suppressing immunological responses in a nonspecific manner. Previously, we have described NS cells in the spleens of mice undergoing chronic graft-versus-host disease (GVHD) and also in normal B10.D2 bone marrow (BM). NS cells obtained from these environments appear dependent upon lymphokines for their ability to manifest suppression. In this report, with anti-IFN-gamma antibody, we show that IFN-gamma is necessary for NS cell activation. Anti-IFN-gamma antibody is able to remove the ability of NS cells to suppress a concanavalin A (Con A) proliferation assay. Also, anti-IFN-gamma antibody removes the ability of rIL-2, lectin-free Con A supernate (CAS), and recombinant IFN-gamma (rIFN-gamma) to enhance NS suppression of lipopolysaccharide response. By these criteria, IFN-gamma is required for NS cell activation, and rIL-2 may act indirectly by its ability to stimulate IFN-gamma synthesis. These results are discussed in the context of the immuno-suppression seen in human BM transplantation.
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PMID:Evidence that IFN-gamma is responsible for natural suppressor activity in GVHD spleen and normal bone marrow. 296 35

In the present investigation, we have studied the antibody response of both C57BL/6 lipopolysaccharide-responder mice (B6 LPS-R) and C57BL/10ScCr LPS-nonresponder mice (B10.Cr LPS-NR) upon immunization with copolymers of LPS and either Ac38 or Ac46 anti-idiotypes. As both strains of mice studied are of the Ighb allotype the antibody response obtained was quantified by estimating the serum levels of the complementary idiotype, B1-8, in immunized mice. The results show that while the injection of the LPS-R strain B6 with copolymers of LPS anti-idiotype resulted in a long-lasting idiotype response the immunization of the LPS-NR strain, B10.Cr, resulted in virtually no response. This finding allowed us to perform cell transfer experiments to study the response of isolated cells from B6 mice transferred into LPS-NR hosts. Using such a cell transfer model, the results obtained suggest that long-lasting idiotype responses observed in the LPS-R strain require continuous B cell production in bone marrow. The relevance of this finding to the understanding of the long-lasting (fluctuating) antibody responses to nondegradable thymus-independent polysaccharides is discussed.
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PMID:Long-lasting thymus-independent immune responses to anti-idiotype lipopolysaccharide conjugates require continuous B cell renewal. 326 22

X-irradiated (250 rad) or normal A mice injected with syngeneic concanavalin A-induced lymphoblasts (syn-Con A blasts) developed an inflammatory response in their footpads 24 to 72 h after injection of syngeneic lipopolysaccharide-induced lymphoblasts (syn-LPS blasts) into these tissues. This immunological activity was designated syngeneic delayed type hypersensitivity (syn-DTH), because T cells transferred the response to naive recipients. Analysis on Ultrogel or Sephadex G-50 columns revealed that a Con A-blast extract contains two syn-DTH-stimulating antigens: a small antigen (6000-7000) and a large antigen (apparent MW of 160,000-175,000). This conclusion held true even when protease inhibitors were included in the fractionation procedure. The approximate molecular weights of these antigens estimated by the gel filtrations were confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The large lymphoblast syn-DTH-stimulating antigen contains carbohydrate residues but not products of the H-2 genetic region. The small antigen does not contain sugar moieties, but it expresses affinity to anti-H-2Dd monoclonal antibody. The immune response to the small antigen but not to the large antigen is genetically restricted at both the induction and the elicitation phases of the DTH. A strain of mice immunized with the small antigen generated syn-DTH after challenge with lymphoblasts of B10.T (6R) mice, which share the H-2Dd subregion with A mice but not the H-2K or the H-2I subregions. Fast protein liquid chromatography of the small antigen yielded a purified material which appeared as a single band after Coomassie staining of its gel electrophoresis.
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PMID:Self-reactive delayed type hypersensitivity induced in mice by syngeneic lymphoblasts. II. Isolation of two distinct lymphoblast antigens, one of which reacts (or cross-reacts) with anti-H-2Dd monoclonal antibody. 342 11


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