Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Modulation of the cyclical response in rabbits to aggregated human gamma globulin (AHuIgG) was investigated in order to study some of the parameters involved in self-regulation of the immune response. Several mitogens (lipopolysaccharide [LPS], phytohemagglutinin [PHA], and concanavalin A [Con A]), when injected simultaneously with antigen, have been shown to modulate the normal splenic plaque-forming cell (PFC) response in rabbits to a single intravenous injection of AHuIgG. This response to AHuIgG has previously been characterized by the initial appearance of PFC in the spleen 3 days later, with a peak of PFC at 5 days after injection. The number of PFC in the spleen then decreases and remains at a low level until a second increase begins on day 10, peaking on day 13. The 8-day cycle between peak PFC repeats, with a third peak appearing on day 21. In the present studies, injection of LPS with AHuIgG was shown to affect the PFC response by enhancing only the initial peak of PFC, PHA was shown to enhance both the initial and secondary peaks of PFC, while injection of Con A with AHuIgG resulted in a prolonged increase in PFC with no apparent cycling. Irradiation 24 h after injection of antigen resulted in PFC kinetics similar to those observed with PHA, although the increase in PFC was more marked with irradiation. Thus, although LPS, PHA, Con A, and irradiation markedly affected the immune response to AHuIgG, Con A was the only substance which altered the cyclical appearance of PFC to HuIgG. The cyclical nature of the PFC kinetics was shown to occur with either intravenous or intraperitoneal injection of antigen and in both primary and secondary responses, provided that the rabbits were primed with a low dose of antigen. Data were obtained that suggest that the response in distal lymph nodes may be regulated by immunological events occurring in the spleen. Cycling of PFC was not observed in the draining node after subcutaneous injection of AHuIgG in the hind foot. However, if the antigen was also injected intravenously at the same time as the subcutaneous injection, the response in the node became cyclical.
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PMID:Modulation of regulatory mechanisms operative in the cyclical production of antibody. 5 57

The addition of low doses of the cationic polypeptide antibiotic, polymyxin B (PB), to cultures of mouse spleen cells inhibits lipopolysaccharide-(LPS) induced DNA synthesis but not that stimulated by PPD, PHA, or Con A. Inhibition is stoichiometric; the mitogenic response is suppressed by 50% at a weight ratio of PB:LPS of 0.055 to 1. Furthermore, PB-LPS complexes have a much reduced mitogenic capacity. These complexes inhibit the mitogenic response of spleen cells to unmodified LPS but not to PPD, Con A, or PHA. The inhibitory activity of PB is less effective when added after LPS is mixed with responding cells, achieving 50% inhibition when addition is made at 4 to 6 hr. Time course experiments indicate that partial inhibition is a reflection of a lower rate of DNA synthesis. Thus, PB inhibition of LPS mitogenesis apparently occurs as a result of formation of PB-LPS complexes with reduced mitogenic capacity. Specific inhibition by the complexes of mitogenesis induced by native LPS suggests that the inactive complex may bind to B cells but is unable to trigger them.
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PMID:Inhibition of the mitogenic response to lipopolysaccharide (LPS) in mouse spleen cells by polymyxin B. 18 99

The in vitro proliferative response of rat lymphoctes culitivated in increasing concentrations of calf serm (LCS) was measured by the incorporation of 3H-thymidine. Results showed that in contrast to the response of PHA, the response to concanavlin A (conA) was greatly dependent on the concentration of serum in the medium. Kinetics of the response of ConA indicated that increasing concentrations of LCS unblocked the non-response to supraoptimal doses of the mitogen. The supportive effect of LCS was not due to an increase in cell viability and was abolished when serum was dialyzed. By contrast, lipopolysaccharide (LPS) exerted an adjuvant effect on the response to optimal and suboptimal concentrations of ConA without unblocking the non-response to high doses. LPS facilitated the response to ConA of a distinct subpopulation of T cell isolated by separation on nylon wool columns. This in vitro model allowed us to study some factors which may be implicated in tolerance and immunity.
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PMID:[Modulation of lymphocyte proliferation by serum factors and lipopolysaccharide]. 30 Jun 1

The functional changes in splenic lymphoid populations from mice infected with T. brucei strain S42 were studied throughout the 3 weeks of infection. Within a week of infection, proliferation of B and T cells profoundly increased as shown by 3H-labelled thymidine incorporation and fluorescent staining of surface Ig; the spleen cells secreted high levels of both IgM and IgG immediately cells were put into culture; but with progressing infection this Ig production declined. The early effect on T cells was reflected by lack of responsiveness to PHA. B-cell potential was studied in low-density cultures treated with lipopolysaccharide (E. coli). Normal spleen cells proliferate extensively in these cultures with subsequent secretion of IgG as well as IgM. The ability to proliferate and produce Ig in response to LPS was severely depressed by day 7 and almost totally absent by day 12 of infection. Removal of T cells from the spleen cells obtained early in infection partly restored the response to LPS but as the infection neared its fatal end, B-cell potential appeared to become exhausted. Macrophages obtained from infected mice even early in infection profoundly depressed the ability of normal spleen cells to proliferate and secrete immunoglobulin in LPS cultures. The general immunodepressing effect of trypanosomes can be attributed to clonal exhaustion of B-cell potential caused by an undefined blastogenic stimulus from the parasites which may operate at least in part by the generation of suppressive T cells and macrophages.
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PMID:Suppressor cells and loss of B-cell potential in mice infected with Trypanosoma brucei. 30 69

Selective growth and clonal proliferation of human T lymphocytes can be achieved by using a single-phase semi-solid methylcellulose system without the requirement of preincubation with lectins. Significant proliferation, however, depends upon the continued presence of Con A or PHA, but not pokeweed mitogen or lipopolysaccharide within the methylcellulose. This procedure eliminates nonspecific agglutination by lectins and allows for direct visualization of colonies and their specific removal and subsequent cloning in liquid phase. Optimal growth and production of colonies greater than 40-cell size require 3 to 9 days. Individual cells can be identified on the basis of E rosette formation and absence of surface immunoglobulin or ability to phagocytize latex particles. Moreover, proliferation is inhibited by antithymocyte but not anti-B cell sera and can be demonstrated with peripheral blood T and MOLT-4 cells, but not with B or Raji cells. Finally, colony formation is not enhanced by the presence of 2-mercaptoethanol. The clonal proliferation of human T lymphocytes has wide application in the study of both antigen recognition and lymphocyte alterations in specific diseases.
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PMID:Select growth of human T lymphocytes in single phase semisolid culture. 30 80

The mitogen effect on migration of eosinophils and monocytes was studied in embryonic chickens. On the 13th embryonic day, chickens were injected with mitogens, such as concanavalin A (Con A), phytohemagglutinin-P (PHA-P), and lipopolysaccharide (LPS), into the allantoic cavity, and the mitogenic effect was estimated from the relative frequencies of eosinophils and monocytes by enumerating the number of oxidase positive cells (OPC) in the spleen, thymus, and bursa of Fabricius. Splenic frequencies of OPC increased in the embryos treated with mitogens. Similar influences were also detected in the thymic OPC. Higher responses were seen on the 18th embryonic day in the number of splenic OPC when embryos were treated with Con A or PHA-P than with LPS. These findings suggest that Con A and PHA-P are preferential OPC accumulation promoters. However, bursal frequencies of OPC in the cortex were low after mitogenic stimulations when compared with controls, although appreciable responses were detected in the bursal medulla after LPS stimulation. These results suggest that the migration pattern in the population of eosinophils and monocytes is affected not only by T cell mitogens but is also derived from LPS stimulation.
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PMID:Accumulation of eosinophils and monocytes in lymphoid organs of chick-embryos. II. Effect of mitogenic stimulation. 49 90

Spleen cells from mice inoculated with partially purified preparations of interferon (Sp. Act. 1 X 10(7) i.u./mg protein, 0.2 ml i. v./mouse) were stimulated in vitro with phytohemagglutinin, concanavalin A or lipopolysaccharide. After 2 days of stimulation, the incorporation of 3H-thymidine into TCA-insoluble radioactivity was inhibited 50-90% when compared with cells from animals inoculated with mock interferon. Maximal inhibition, with optimal doses of lectins was obtained when interferon was;inoculated 18 hours before. This effect of interferon on DNA synthesis was preceeded by inhibition of the incorporation of 3H-uridine into TCA-insoluble material. When cells were pretreated in vitro with interferon for 24 hours and subsequently stimulated with PHA, RNA synthesis was inhibited by 30-40%, whatever was the dose of the mitogen. The synthesis of 4S tRNA, 18S and 28S ribosomal RNAs were inhibited to the same degree by interferon. The incorporation of methyl groups into cytoplasmic sRNA was unaltered.
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PMID:Inhibitory effect of interferon on DNA and RNA synthesis in murine spleen cells stimulated by lectins. 93 1

Dextran sulphate, polyvinyl sulphate and carrageenan (but not the other polyanions tested, such as poly I:poly C, poly-L-glutamic acid or E. coli lipopolysaccharide) act synergisticaly with PHA on mouse thymocyte stimulation, as measured by thymidine uptake and blast cell transformation. Furthermore the active compounds shift the dose response of thymocytes to Con A. The effect could be observed in four different strains of mice tested by using normal or cortisone-resistant thymocytes. Two possibilities are envisaged for explanation of these effects: (a) attachment of polyanions by their anionic groups to cell surface constituents and interaction of the sulphate groups of the polymers with plant lectins; and (b) modification of the cell membrane induced by sulphated polymers changing either the binding capacity or the effectiveness of the membrane-associated events leading to thymocyte stimulation by the lectins.
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PMID:Changes in thymocyte reactivity to lectins induced by B-cell mitogens of the type of sulphated polyanions. 108 28

Sera from old (greater than 6 months) New Zealand Black (NZB) mice were shown to contain an IgM antibody which was cytotoxic for thymus-derived (T) lymphocytes in the presence of rabbit complement. This antibody in the presence of complement markedly decreased the response of normal spleen cells to the T cell mitogen concanvalin A (Con A) but not to another T cell mitogen phytohemagglutinin-P (PHA-P). Responses of these treated cells to the polyclonal B cell mitogens, bacterial lipopolysaccharide (LPS), and polyriboinosinic-polyribocytidylic acid (poly[I]-poly[C]) were unimpaired. This naturally occurring NZB antibody was different from conventional anti-theta serum which abolished the response to both PHA-P and Con A. Moreover, the NZB serum affected spleen cells from both theta-C3H and theta-AKR mice. The ability of such serum to influence, differentially, Con A reactive cells as opposed to PHA-P-reactive cells, suggest that the NZB antiserum recognizes a subpopulation of T lymphocytes.
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PMID:Functional characterization of a naturally occurring antibody cytotoxic for a subpopulation of splenic T cells. 108 8

Functional immune changes were monitored in populations of the long-lived C57BL/6J strain of mice which were subjected to dietary restriction from time of weaning or subjected to such restriction both before and after weaning, along with the appropriate control populations. Responses to T and B cell mitogens (PHA, Con-A, pokeweed, bacterial lipopolysaccharide, and PPD), to injected sheep red blood cells, and measurement of skin allograft rejection rates were followed. Early in life, restricted mice appear immunosuppressed, as judged by all these parameters. Skin allograft rejection remained suppressed until relatively late in life. Other responses tended to reverse from the earlier pattern; by mid-life restricted mice responded better than controls. Dietary restriction profoundly affects the immune system. Mice on such regimes display anatomic and certain immune functional changes which suggest that the immune system may mature less rapidly and stay "younger" longer than in the controls. Furthermore, dietary restriction results in prolongation of life span.
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PMID:Immune function and survival in a long-lived mouse strain subjected to undernutrition. 110 95


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