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

Matrix-bound fibronectin (FN) appears to be involved in cell adhesion and motility mediated by integrin receptors. Although lymphoid cells and other cell types are capable of producing and secreting FN, the precise role of this secreted FN-like factor in regulating immune reactions is unclear. In the present study we analyzed the adhesive properties of FN secreted by rat CD4+ T cells and clone cells activated by the T cell mitogen concanavalin A (Con A), antigen, or via the CD2 pathways, or by macrophages (M phi) activated by lipopolysaccharide (LPS). Immobilized culture supernatant (CS) from the activated T cells or M phi supports the adhesion of activated rat or human CD4+ T cell or murine tumor cell. These CS contained FN and were more potent at facilitating cell adhesion then plasma FN. The adhesion activity of CS was attributed to FN because (a) gelatin columns depleted the FN present in the CS and (b) pretreating the cells with peptides of the cell-binding domain of FN abrogated their ability to bind CS. CS-mediated adhesion appears to occur primarily via the recognition of the Arg-Gly-Asp (RGD) by the beta 1-integrin-specific receptors of the adhesive cells. Thus, we postulate that FN secreted by various types of leukocytes is involved in promoting essential cell-matrix interactions, possibly affecting cell-adhesive and migratory processes at inflammatory or extravasation sites.
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PMID:Activated T lymphocytes and macrophages secrete fibronectin which strongly supports cell adhesion. 157 55

Morphological and functional characteristics of a permanent human leukemia cell line (DD) that possesses myelomonocytic features were investigated. The cells bear a second type Fc gamma receptor and form rosettes with sheep erythrocytes sensitized with rabbit IgG (EA). However, the surface-bound EA is not internalized. The cell line lacks the surface markers CD2, CD19, CD14, HLA-DR, Fc gamma receptor I, Fc gamma receptor III, and CR3. alpha 1-Antitrypsin, lysozyme, Factor XIII a subunit of blood coagulation, and acid phosphatase reactions were negative. A terminal differentiation of the DD cell line was observed when the expression of CD14, CR3, Fc gamma receptor I, and Fc gamma receptor III was induced. The DD cells induced with 12-O-tetradecanoylphorbol-13-acetate or Escherichia coli lipopolysaccharide can internalize EA via Fc gamma receptor II and complement-coated yeast in the function of the inducers. The phagocytic ability appears to be parallel with the appearance of enzymes which participate in phagocytosis.
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PMID:Marker profile, enzyme activity, and function of a human myelomonocytic leukemia cell line. 173 17

We here report the finding that the anti-inflammatory cytokine interleukin-10 (IL-10) inhibits motility of B lymphocytes. B cells were induced to display motile morphology and active migration by IL-4. IL-10 inhibited locomotor responses to IL-4, when B cells of both murine and human origin were used. The inhibitory effect of IL-10 was reversible, since washing of B cells preincubated in IL-10 restored the ability to respond to IL-4. Time-course experiments showed that IL-10 did not have to be present from the very onset of culture, but could be added as late as 5 hr after initiation. In addition, murine B cells stimulated with lipopolysaccharide (LPS) showed motile morphology, as well as cellular aggregation and proliferation. All these parameters were suppressed by IL-10. However, viability of B cells was not adversely affected by IL-10. Exposure to IL-10 did not result in any changes in the surface expression of molecules involved in adhesion, such as CD2, CD11a/CD18, CD44, CD54 or L-selectin, on B lymphocytes.
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PMID:Interleukin-10 inhibits motility in murine and human B lymphocytes. 795 71

Transgenic mice carrying a modified human tumour necrosis factor (huTNF)/beta-globin gene construct linked to the T-cell-specific locus control region of the human CD2 gene express huTNF in their T cells which is released into the circulation and causes the development of a wasting syndrome. We now report that the mice develop anaemia, probably through enhanced erythrophagocytosis rather than inhibition of reticulocyte production. Thus autologous erythrocytes, as well as sheep erythrocytes, were cleared more rapidly from the circulation of transgenic mice than from littermate controls. By contrast, peritoneal macrophages from transgenic mice were less phagocytic in vitro than cells from controls. They also secreted less murine (mu)TNF when stimulated by either bacterial lipopolysaccharide or toxic malarial antigens. The yields of muTNF approached normal levels, however, when these refractory cells from the transgenic mice were stimulated in the presence of a high concentration of indomethacin, suggesting that the production of muTNF was inhibited by enhanced synthesis of prostaglandins. The parasitaemia of transgenic mice infected with Plasmodium yoelii was about 10-fold less at its peak than in controls, although it followed the same time-course, and the multiplication of P. chabaudi was inhibited to an even greater degree. This control of parasitaemia may also be explained by enhancement of macrophage activity, mediated by huTNF acting on the murine p55 receptor, presumably by increasing the removal of parasites by phagocytosis or their killing by toxic products released by the activated macrophages. These observations suggest that a factor in the anaemia of human malaria may be macrophage activation caused by the secretion of TNF that occurs in this disease.
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PMID:Anaemia and resistance to malaria in transgenic mice expressing human tumour necrosis factor. 795 74

We investigated interleukin-10 (IL-10) production in freshly isolated mononuclear cells and purified T cells in response to stimulation with monoclonal antibodies (mAb) recognizing CD3, CD2 and CD28, or with the bacterial products Staphylococcus aureus cells (SAC), staphylococcal enterotoxin (SEA) and lipopolysaccharide (LPS). IL-10 production was compared with that of IL-2, IL-4 and interferon-gamma (IFN-gamma). Similar to the other cytokines, in peripheral blood mononuclear cells (PBMC) from adult donors the highest IL-10 levels were produced in response to CD2 plus CD28 stimulation, within 72-96 hr of stimulation. Levels of IL-10 in response to CD2 plus CD28 stimulation (1.9 +/- 1 ng/ml) exceeded those in response to SEA (0.25 +/- 0.16 ng/ml), SAC (0.43 +/- 0.42 ng/ml), or LPS (0.19 +/- 0.14 ng/ml) stimulation. With adult purified T cells, high levels of IL-10 and IL-4 were measured following CD3 plus CD28 stimulation, and the amounts of both T-helper type-2 (Th2) cytokines decreased following the addition of phorbol myristate acetate (PMA), whereas the synthesis of the Th1 cytokines IL-2 and IFN-gamma was enhanced. When PBMC were stimulated with a CD3 mAb and different other cytokines were added, strong enhancement of IL-10 production was seen upon the addition of IL-2, IL-4, IL-7, IL-12 and IFN-gamma, whereas inhibition was found with transforming growth factor-beta 1 (TGF-beta 1). These data illustrate that in freshly isolated PBMC large amounts of IL-10 can be induced rapidly by appropriate mAb stimulation, and that even in freshly isolated cells IL-4 and IL-10 show signs of parallel regulation.
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PMID:High-level IL-10 production by monoclonal antibody-stimulated human T cells. 855 72

Experimental data show that relatively low concentrations of 15-deoxyspergualin (DSG) inhibit the induction of cytotoxic T lymphocytes (CTL) and the generation of antibody-producing cells. Considerably higher concentrations of DSG are required to inhibit proliferative responses. In this in vitro study, the effects of DSG on CTL induction, on proliferative responses induced by different stimuli, and on the production of interleukins IL-1, IL-2 and IL-6 and IFN-gamma (gamma-interferon) were assessed and compared with the effects of CsA (cyclosporine A) and/or FK506. We confirmed the suppressive action of DSG on the generation of CTL. Quite unexpectedly, however, we found that, although DSG did not affect the proliferative response to allogeneic lymphocytes or a superantigen, it did inhibit proliferation of peripheral blood leucocytes (PBL) stimulated with Staphyloccus aureus. DSG was active even when added on day 2 of in vitro culture, suggesting that DSG does not inhibit early events. The fraction of CD3+ lymphoblasts and the CD4/CD8 ratio was lower in cells stimulated by S. aureus in the presence of DSG, showing a selective effect on CD3+CD4+ responder T lymphocytes. The proportion of IL-2 receptor (CD25) positive cells was also reduced by DSG treatment. Moreover, we found that DSG inhibited the proliferation induced by PHA (phytohaemagglutinin) but not by Con A (concanavalin A). This effect of DSG was time-dependent, since PHA induced proliferation was not affected until day 4 after stimulation, and indicated that DSG may inhibit proliferation induced via a CD2- but not via a CD3-mediated pathway. DSG did not influence the production of IL-2 or IFN-gamma or the lipopolysaccharide induced production of IL-2 or IL-6. In contrast, the production of IL-6 was inhibited when cells were stimulated by allogeneic lymphocytes, S. aureus, PHA or Con A. This suggested to us that the DSG-suppressed IL-6 production could be the basis for the other observed effects. We tried to mimic the DSG effects with antibodies and indeed found that the IL-6 specific antibodies had similar effects. Furthermore, recombinant IL-6 completely overcame the suppressive effects of DSG on S. aureus and PHA induced proliferation, whereas addition of IL-6 to DSG treated PBL only partly restored the cytotoxic activity of lymphoblasts induced by allogeneic cells. Thus, the inhibitory effect of DSG on de novo synthesis of IL-6 could explain some of its immunosuppressive effects, but additional DSG-sensitive steps are obviously involved in CTL induction and differentiation.
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PMID:15-Deoxyspergualin inhibits interleukin 6 production in in vitro stimulated human lymphocytes. 884 90

Age related differences in immunological reactions include variations in the in vitro functions of blood mononuclear cells (MNC). In an attempt to understand the mechanism behind these differences we examined age related differences in the phenotype profiles of MNC in parallel with the in vitro production of interleukin IL-6, tumour necrosis factor alpha (TNF alpha) and interferon gamma (IFNg) in neonates, children and adults. In cultures without added polyclonal activators IL-6 and TNF alpha levels in children were 3-6 times higher than those of umbilical cords and adults. However, using optimal in vitro stimulation (E. coli lipopolysaccharide (LPS), phytohaemmagglutinin or pokeweed mitogen (PWM)) no significant differences in the levels of these cytokines were observed. The levels of IFNg in PWM driven cultures followed a different pattern with comparable levels in children and adults, and unmeasurable levels in cord blood MNC. Flow cytometry analysis of the phenotypic distribution of MNC revealed age related differences in the expression of CD3, CD4, CD8, CD14, CD19, CD45RA, CD45R0, CD2, LFA-1, ICAM-1 and LFA-3. Correlation studies did not indicate that the observed differences in cytokine production could be ascribed to differences in the frequency of monocytes, T cells or B cells. The TNF alpha levels in suboptimally stimulated cultures correlated negatively with the expression of LFA-3 and positively with CD45RA, while IFNg correlated positively with CD2, LFA-1, CD45R0 and CD8. In conclusion, the study provides evidence of age related differences in the production of TNF alpha, IL-6 and IFNg among neonates, children and adults. These differences may to some extent be caused by differences in the expression of cell surface molecules involved in cellular interactions and signalling.
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PMID:In vitro cytokine production and phenotype expression by blood mononuclear cells from umbilical cords, children and adults. 911 75

Glucocorticoids (GC) play an important role in the treatment of inflammatory diseases like asthma. However, in selected patients a relative resistance to GC has been reported. Recently, it has been suggested that GC sensitivity of peripheral blood leucocytes may be regulated in a dynamic fashion during exercise, in association with activation of the hypothalamic-pituitary-adrenal (HPA) axis. The aim of the present study was to explore changes in the GC sensitivity of cytokine production by leucocytes following strenuous exercise by well trained oarsmen. These changes were studied using lipopolysaccharide (LPS)-induced and anti-CD2/anti-CD28 MoAb-stimulated cytokine release in whole blood and its modulation by dexamethasone. Following exercise, significant decreases in LPS-induced release of IL-6, tumour necrosis factor-alpha (TNF-alpha) and IL-10 and anti-CD2/anti-CD28 MoAb-stimulated secretion of interferon-gamma (IFN-gamma) were observed. In addition, the inhibitory effect of dexamethasone on both IL-6 and TNF-alpha secretion was significantly reduced following exercise, whereas that on IL-10 and IFN-gamma release was not affected. These exercise-induced changes were accompanied by activation of the HPA axis, as indicated by an increase in circulating adrenocorticotropic hormone (ACTH) levels immediately following exercise. The results from the present study suggest that GC sensitivity of whole blood cytokine release can be regulated in a dynamic fashion and that this can be assessed using an ex vivo stimulation assay. Moreover, since dexamethasone responsiveness of anti-CD2/anti-CD28 MoAb-induced IFN-gamma secretion in whole blood is not affected by exercise, it may suggest that exercise differentially affects monocytes and lymphocytes. The dynamic regulation of steroid responsiveness of leucocytes, as observed in the present study, could have important consequences for the effectiveness of GC treatment in inflammatory diseases.
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PMID:Cytokine release and its modulation by dexamethasone in whole blood following exercise. 948 20

In this paper, we describe that met-enkephalin and/or enkephalin-containing intermediary peptides of the prohormone pro-enkephalin A are produced and secreted by human peripheral blood T cells and monocytes. The peptides are produced after stimulation with the mitogenic monoclonal antibodies anti-CD2.1/2.2 and anti-CD28. In monocytes, enkephalin synthesis was induced by stimulation with lipopolysaccharide. We demonstrate here that these immune cell-derived enkephalins play an important regulatory role in the immune response. By using an anti-sense oligonucleotide strategy we could block the production of enkephalins. Blockade of the production of met-enkephalin and enkephalin-containing intermediary peptides resulted in enhancement of the proliferative T cell response and inhibition of monocyte IL-6 secretion. In vitro reconstitution of the anti-sense treated cultures with synthetic met-enkephalin or the delta-type specific opioid receptor agonist deltorphin could reverse inhibition of monocyte IL-6 production, suggesting that endogenous enkephalins act via membrane opioid receptors. In contrast, addition of met-enkephalin or deltorphin to the anti-sense treated T cell cultures did not have any effect on T cell proliferation.
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PMID:Role of endogenous pro-enkephalin A-derived peptides in human T cell proliferation and monocyte IL-6 production. 960 Jul 8

Fourier transform infrared (FTIR) spectroscopy has been used to study the thermotropic phase behavior of binary lipid mixtures composed of deuterated phospholipids (PLs) and lipopolysaccharides (LPSs). Furthermore, the influence of an extrinsic high-molecular, polycationic polypeptide (poly-(L-lysine), PLL(500)) and an intrinsic membrane protein (outer membrane protein F, OmpF) on these binary mixtures was investigated by FTIR spectroscopy. "Deep rough" mutant LPS (ReLPS), isolated from Salmonella minnesota R595, and perdeuterated 1,2-dimyristoylphosphatidylethanolamine (DMPEd54) were used as model lipids. Deuteration of one of the lipids permitted the detection of lipid protein interaction with each lipid component separately. For this purpose, the symmetric >CH2 and >CD2 stretching bands were utilized as specific monitors to scrutinize the state of order of the membranes. From the individual phase transition temperatures Tm and the shape of the phase transition profiles, it is established that ReLPS and DMPEd54 are molecularly immiscible. In addition to the two domains of the pure lipid components, a third, domain-like structure is detected that may coexist with these pure domains. This domain-like structure undergoes a gel to liquid-crystalline L1 (beta <--> alpha) phase transition at temperatures distinctly different from that of the respective pure lipid domains. The nature of this type of domain is discussed in terms of a "border region" model that adequately explains the experimentally observed complex phase transition profiles. It is further demonstrated that the extrinsic polycationic polypeptide PLL(500) and the intrinsic, pore-forming protein OmpF isolated from Escherichia coli interact preferentially and highly specifically with the negatively charged ReLPS. Both the synthetic polypeptide and the pore-forming protein increased the tendency of ReLPS and DMPEd54 to segregate into distinct, well-separated domains. Whereas the transition profiles of the ternary system ReLPS/DMPEd54/PLL(500) showed the features of a phase segregation phenomenon not affecting the transition temperatures of the pure lipid components, the ternary system composed of ReLPS/DMPEd54 and OmpF exhibited phase transition curves that were characterized by an unspecific (DMPEd54/OmpF) and a strong and unique (ReLPS/OmpF) type of lipid-protein interaction. Furthermore, semiquantitative estimations supported the supposition that OmpF might be able to induce bilayer asymmetry in preformed symmetrical ReLPS/DMPEd54 vesicles.
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PMID:The influence of poly-(L-lysine) and porin on the domain structure of mixed vesicles composed of lipopolysaccharide and phospholipid: an infrared spectroscopic study. 967 85


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