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

The relative RNA content of single macrophages was measured by cytofluorometry after differential staining of cellular DNA and RNA with the metachromatic fluorescent dye acridine orange. This method allowed the differentiation of two major groups in the adherent macrophage population differing in their RNA content. After in vivo stimulation of mice (by injection of thioglycollate medium) or guinea pigs (by injection of oil), an increasing percentage of macrophages possessing a high RNA content is recovered. In vitro stimulation of macrophage cultures with lipopolysaccharide had the same enhancing effect on cellular RNA content. Cytofluorometric measurement of RNA content may possibly become an efficient and rapid method of measuring macrophage activation.
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PMID:Cytofluorometric analysis of macrophages activated in vivo or in vitro. 7 52

Three techniques for the measurement of bacterial numbers and biomass in the marine environment are described. Two are direct methods for counting bacteria. The first employs an epifluorescence microscope to view bacteria that have been concentrated on membrane filters and stained with acridine orange. The second uses a transmission electron microscope for observing replicas of bacteria that are concentrated on membrane filters. The other technique uses Limulus amebocyte lysate, an aqueous extract from the amebocytes of the horseshoe crab, Limulus polyphemus, to quantitate lipopolysaccharide (LPS) in seawater samples. The biomass of gram-negative (LPS containing) bacteria was shown to be related to the LPS content of the samples. A factor of 6.35 was determined for converting LPS to bacterial carbon.
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PMID:Determination of bacterial number and biomass in the marine environment. 32 92

The influence of Y. pestis phospholipase D on the physiological state of leukocytes in the blood of guinea pigs was studied in vivo by flow impulse fluorometry with the use of fluorochrome acridine orange. During the first hours of observation the intensity of leukocyte fluorescence increased due to a rise in the number of polymorphonuclear leukocytes and changes in the permeability of cell membranes. Further changes in the intensity of the fluorescence of the material under study after 24 hours of observation occurred due to the appearance of activated lymphocytes in the blood stream. The processes normalized by day 21. The reaction of blood leukocytes to phospholipase D was specific in comparison with the reaction to capsular antigen, "mouse" toxin, lipopolysaccharide and the main somatic antigen.
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PMID:[A comparative cytofluorimetric analysis of the blood leukocytes in guinea pigs exposed to the phospholipase D and antigens of the causative agent of plague]. 130 64

Earlier studies in our laboratory showed that the lipopolysaccharide (LPS) of Salmonella typhi, which fails to activate B lymphocytes of C3H/HeJ mice, can suppress proliferation and polyclonal antibody synthesis by these cells when they are stimulated by polyclonal activators. In order to determine what stage of the cell cycle was blocked, resting B cells from C3H/HeJ spleens were activated by using different mitogens in the presence of inhibitory concentrations of LPS and analyzed by flow cytometry, using acridine orange to stain DNA and RNA. LPS was found to inhibit the progression of cells into the G1 stage of the cell cycle. Furthermore, [3H]uridine uptake studies showed that RNA synthesis is inhibited during the early phase of activation. These results indicate that inhibition by LPS of the signalling process occurs during a critical period of the cell cycle when the cells become susceptible to the inhibitory effects of LPS. To examine whether LPS acts only on B cells or whether it can suppress other immunocompetent cells from C3H/HeJ mice, studies were carried out on activated thymocytes and macrophages. LPS was found to inhibit thymocyte proliferation stimulated by concanavalin A or the combination of phorbol myristate acetate and ionomycin. Prostaglandin E2 synthesis by macrophages was also blocked by LPS. Thus, LPS is a potent inhibitor of the functioning of the major immunocompetent cells of C3H/HeJ mice.
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PMID:Suppression of C3H/HeJ cell activation by lipopolysaccharide endotoxin. 137 86

Normal and tumor-bearing host (TBH) peritoneal macrophage (M phi) responses to in vitro lipopolysaccharide (LPS) treatment were measured by assessing functional and phenotypic changes. Both normal and TBH untreated M phi suppressed mixed lymphocyte reaction (MLR) reactivity at all concentrations. Normal host M phi treated with LPS for 3 h were suppressive at all concentrations. TBH M phi treated with LPS for 3 h were not suppressive in the MLR until more than 5% were added. Surprisingly, 24 h treatment of normal and TBH M phi with LPS induced cells that significantly enhanced MLR reactivity when added at 2% or 5%. These cells were not suppressive until a 20% M phi concentration was reached. LPS treatment of normal and TBH M phi changed the percentage of cells expressing the surface markers Mac-1, -2, -3, and Ia as determined by flow cytometry. Normal host peritoneal M phi treated with LPS for 3 h had decreased Mac-1 and -3 expression, but there was no change in Mac-2 or Ia. Plating for 24 h did not change the percentage of M phi expressing Mac-1, -3, or Ia but did cause an increase in Mac-2+ M phi. Treatment of normal host M phi with LPS for 24 h led to a decrease in Mac-1+ and Ia+ M phi, no change in Mac-3+ M phi, but an increase in Mac-2+ M phi. LPS treatment of TBH M phi for 3 h decreased the number of Mac-1+ M phi, but Mac-2+, -3+, or Ia+ M phi numbers did not change. Plating TBH M phi for 24 h caused a decrease in the number of Mac-1+ M phi, no change in Mac-3+ or Ia+ M phi, but an increase in Mac-2+ M phi. Treatment with LPS for 24 h led to no change in the number of Mac-1+, -3+, or Ia+ TBH M phi, but Mac-2+ M phi increased. The phenotypic and functional changes after LPS treatment led us to ask if these changes were detectable at the level of DNA and RNA. Flow cytometric analysis of acridine orange-stained M phi was used to measure DNA and RNA levels. This analysis determines M phi cell-cycle kinetics and estimates their RNA synthesis. In normal host M phi, a 3-h LPS treatment caused a decrease of cells in G0/G1 but an insignificant change in RNA levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Normal and tumor-bearing host macrophage responses: variability in accessory function, surface markers, and cell-cycle kinetics. 169 10

An immunomagnetic technique to detect and identify Salmonella serogroup C1 has been developed. Monoclonal antibodies (MAbs) specific for the O antigen 6,7 of Salmonella lipopolysaccharide (LPS) coupled to magnetic beads were used to isolate the salmonellae. Captured bacteria were easily identified by acridine orange staining and measured by enzyme immunoassays with a conjugate anti-LPS MAb as the detector probe. The whole detection process required 2-3 h and the sensitivity was 10(3)-10(4) bacteria/ml. The presence of blood (10%, v/v) or stool (1%, w/v) components did not interfere with the immunomagnetic assay performance.
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PMID:Rapid and sensitive detection of Salmonella (O:6,7) by immunomagnetic monoclonal antibody-based assays. 170 80

The phagocytosis of Haemophilus influenzae type b (Hib) by rat macrophages and the intracellular fate of ingested organisms was investigated using an acridine orange-crystal violet assay. There was a correlation between the ability of organisms to survive in macrophages in vitro and their ability to cause invasive disease. Encapsulated Hib survived and replicated within macrophages, whereas capsule-deficient mutants, although more susceptible to phagocytosis, were killed after ingestion. Differences in lipopolysaccharide also affected the ability of encapsulated Hib to survive in macrophages. The presence of viable intracellular organisms in macrophages in vivo may enhance the persistence of bacteremia and may also be important in mediating the entry of Hib into the central nervous system.
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PMID:Relationship between intracellular survival in macrophages and virulence of Haemophilus influenzae type b. 203 2

A murine monoclonal antibody (MoAb) B3 to rat cells and MoAb HBJ127 and HBJ98 to human cells were found previously to recognize the homologous antigen systems (gp130 in the rat and gp125 in the human) which are predominantly distributed on the cell surface of proliferating cells of the respective species, and the expression of the antigen systems in lymphocytes were indicated previously to correlate closely with the activation and proliferation of the lymphocytes. In this respect, the in vitro effects of these MoAb on the nucleic acid synthesis, cell cycles, or proliferation of stimulated rat and human lymphocytes were examined by use of T cell-enriched and B cell-enriched cell populations. The addition of B3 MoAb to cultures diminished Con A-induced or allogeneic mixed lymphocyte culture-induced rat T cell proliferation and lipopolysaccharide-induced rat B cell proliferation, whereas B31 MoAb, which is unreactive with the gp130 antigen, did not inhibit these lymphocyte responses. Similarly, both HBJ127 and HBJ98 MoAb could inhibit the human lymphocyte proliferation in vitro, although HBJ127 MoAb showed about eight times greater inhibitory activity than did HBJ98 MoAb; HBJ127 MoAb almost completely inhibited the DNA synthesis of the Con A-stimulated lymphocytes at concentrations higher than 13 micrograms/ml. The flow cytometric analysis of the cellular nucleic acid contents with acridine orange-stained cells showed that when B3 MoAb and Con A were simultaneously added to unstimulated rat T cells, progression of the cell cycle was blocked at the G0 to G1 transition. In this culture condition, the appearance of the B3-defined antigen was arrested in a moderate level, as determined with fluorescein-stained cells. On the addition of B3 MoAb to the culture of the T cells after 24-hr Con A stimulation, the MoAb also strongly inhibited the cellular DNA synthesis, but it did not arrest the cell cycle at a certain phase and did not modulate the corresponding antigen. These data suggest that the B3 MoAb-defined antigen on the rat lymphocytes and the HBJ127/HBJ98 MoAb-defined antigen on the human lymphocytes may play some requisite roles not only in lymphocyte activation but also in the subsequent progression through the cell cycle to proliferate.
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PMID:Monoclonal antibodies that inhibit activation and proliferation of lymphocytes. II. Requisite role of the monoclonal antibody-defined antigen systems in activation and proliferation of human and rat lymphocytes. 241 21

There have been two recent reports concerning a B cell-specific mitogen that induces proliferation, but not differentiation of rat and human B cells. This mitogen, which is derived from Salmonella typhimurium (STM), appears to be providing the signals required for anti-immunoglobulin-treated (anti-Ig) B cells to enter cycle and divide, but may not be inducing responsiveness to B cell differentiation factors (BCDF). In this report, we have compared STM to the other known murine B cell polyclonal activators: lipopolysaccharide (LPS), dextran sulfate (DxS), and the combination of LPS/DxS. STM was the most potent stimulus of B cell proliferation as determined by uptake of 3H-thymidine, viable cell numbers and cell cycle analysis utilizing acridine orange (AO). STM did not induce significant proliferation of murine T lymphocytes. In addition, the proliferative effect of STM on B cells shows minimal, if any, macrophage dependence. However, in contrast to its effect on human and rat B cells, STM induces differentiation of murine B cells. The levels of cytoplasmic Ig induced by STM are equivalent or greater to those induced by LPS/DxS. Thus, in the murine system, STM will be useful as a polyclonal activator which induces proliferation and differentiation of the vast majority of the B cell population without stringent accessory cell requirements.
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PMID:Activation of murine B cells with Salmonella typhimurium mitogen (STM), lipopolysaccharide (LPS), and dextran sulfate (DxS). I. Cell-cycle analysis and induction of cytoplasmic immunoglobulin. 247 69

During the screening of suppressor T cell (Ts) hybridomas for antigen-nonspecific suppressive activity, we isolated a strain of Mycoplasma arginini which inhibits B cell antibody production in vitro. The addition of mycoplasma-containing Ts hybridoma culture supernatant to splenic B cells responding to sheep red blood cells (SRBC) and T cell-replacing factor or to trinitrophenyl-lipopolysaccharide (TNP-LPS) suppressed the production of anti-SRBC and anti-TNP plaque-forming cells in a dose-dependent and antigen-nonspecific manner. Inhibition occurred due to the noncytotoxic mycoplasmal infection of B cells in culture and required the physical presence of microorganisms. Cell cycle analysis of acridine orange-stained B cells indicated that mycoplasmal infection did not block cell cycle entry and progression of antigen-activated cells. In addition to a suppressive activity, this strain of mycoplasma was selectively mitogenic for B cells. Furthermore, the mycoplasma failed to stimulate or inhibit T cell proliferation. The suppressive and mitogenic activities were selectively absorbed by mitogen-activated B cells but not T cells. These results indicate that this strain of M. arginini mimics the suppressive activity of an antigen-nonspecific Ts factor selective for B cell antibody production.
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PMID:The regulation of murine B cell differentiation. I. Nonspecific suppression caused by Mycoplasma arginini. 279 Sep 65


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