concanavalin-a and Salmonella-Infections--Animal

A vaccine strain of live, attenuated Salmonella typhimurium induces profound immunosuppression in inoculated mice 7 days after injection. Immunosuppression to mitogens and inability to mount plaque-forming responses to sheep red blood cells occurs in spite of many parameters of upregulated macrophage function and protection against challenge with virulent Salmonella. Studies show that macrophage nitric oxide mediates the immunosuppression and presumably also the early-onset protective capacity of the vaccine. A model of "bystander lymphocyte autotoxicity" is presented to explain the mechanism of immunosuppression. The model proposes that Salmonella-activated macrophages generate nitric oxide which inactivates lymphocytes in the vicinity, so they become dysfunctional. Inhibition of nitric oxide by NG-monomethyl-L-arginine reverses immunosuppression. Evidence is presented that supports a relationship between the microbial burden in the spleen, the degree of nitric oxide produced, and the extent of immunosuppression. It is proposed that this model of microbial immunosuppression mediated by nitric oxide is generalizable for understanding immunosuppression and loss of delayed-type hypersensitivity induced by other microbes, such as Mycobacteria and measles virus. The model could account for anergy during mycobacterial infections, particularly when the burden of acid-fast bacilli is high, as well as loss of skin test reactivity to tuberculin during measles infection.

Topics: Animals; Arginine; Bacterial Vaccines; Concanavalin A; Immune Tolerance; Inflammation; Lymphocytes; Macrophages; Mice; Nitric Oxide; omega-N-Methylarginine; Salmonella Infections, Animal; Salmonella typhimurium; Suppressor Factors, Immunologic

Our previous work showed that the cell-mediated immunity (CMI) was enhanced by live Salmonella vaccine (LV). The objective of this study was to evaluate the impact of live and killed Salmonella vaccines on Salmonella enteritidis (SE) clearance and to determine if the clearance was mediated by cell-mediated and/or humoral immunity. Chickens were first immunized at 2 weeks of age followed by a booster dose at 4 weeks, challenged with live SE 2 weeks later (6-week-old) and tested for CMI, antibody response and SE clearance 1-week post SE-challenge (7-week-old). Spleen cell proliferation induced by SE-flagella and Concanavalin A (Con A) were significantly higher and SE shedding was significantly lower in the LV group. The splenic CD3 population was significantly lower and B cells were higher in the control group compared to all the SE-challenged groups (with and without vaccination). Serum antibody to SE-flagella and envelope were significantly higher in the KV group compared to all the other groups. These results suggest that LV protects against SE infection, probably by enhancing the CMI.

Topics: Animals; Antibodies, Bacterial; Cell Division; Chickens; Concanavalin A; Feces; Flagella; Flow Cytometry; Poultry Diseases; Salmonella enteritidis; Salmonella Infections, Animal; Salmonella Vaccines; Specific Pathogen-Free Organisms; Spleen; Statistics, Nonparametric; Vaccines, Attenuated; Vaccines, Inactivated

Infection remains the major complication of immunosuppressive therapy in organ transplantation. Therefore, reconstitution of the innate immunity against infections, without activation of the adaptive immune responses, to prevent graft rejection is a clinically desirable status in transplant recipients. We found that GM-CSF restored TNF mRNA and protein expression without inducing IL-2 production and T cell proliferation in glucocorticoid-immunosuppressed blood from either healthy donors or liver transplant patients. Gene array experiments indicated that GM-CSF selectively restored a variety of dexamethasone-suppressed, LPS-inducible genes relevant for innate immunity. A possible explanation for the lack of GM-CSF to restore T cell proliferation is its enhancement of the release of IL-1betaR antagonist, rather than of IL-1beta itself, since exogenously added IL-1beta induced an IL-2-independent Con A-stimulated proliferation of glucocorticoid-immunosuppressed lymphocytes. Finally, to test the in vivo relevance of our findings, we showed that GM-CSF restored the survival of dexamethasone- or cyclosporine A-immunosuppressed mice from an otherwise lethal infection with Salmonella typhimurium. In addition to this increased resistance to infection, GM-CSF did not induce graft rejection of a skin allotransplant in cyclosporine A-immunosuppressed mice. The selective restoration potential of GM-CSF suggests its therapeutic use in improving the resistance against infections upon organ transplantation.

Topics: Adjuvants, Immunologic; Adult; Aged; Animals; CDC2-CDC28 Kinases; Cell Cycle Proteins; Cell Division; Cell Separation; Concanavalin A; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase Inhibitor p27; Cyclin-Dependent Kinases; Dexamethasone; Down-Regulation; Gene Expression Regulation; Graft Rejection; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Immunity, Active; Immunity, Innate; Immunosuppressive Agents; Interleukin-1; Interleukin-2; Leukocytes, Mononuclear; Lipopolysaccharides; Mice; Mice, Inbred CBA; Middle Aged; Protein Serine-Threonine Kinases; Salmonella Infections, Animal; Skin Transplantation; Survival Rate; T-Lymphocytes; Tumor Cells, Cultured; Tumor Suppressor Proteins; Up-Regulation

The plant lectins, Concanavalin A (Con A) and Galanthus nivalis agglutinin (GNA) have been prefed to rats for 3 d pre- and 6 d postinfection with Salmonella typhimurium S986 or Salm. enteritidis 857. Con A significantly increased numbers of Salm. typhimurium S986 in the large intestine and in faeces, and severely impaired growth of the rats, more severely than is the case of infection with Salmonella typhimurium alone. Con A had much less effect on rats infected with Salm. enteritidis 857 only showing a significant increase in numbers in the colon, accompanied by intermittent increases of Salmonella in the faeces during the study. GNA significantly reduced pathogen numbers in the lower part of the small bowel and the large intestine of rats infected with Salm. typhimurium S986 and significantly improved rat growth. GNA had little effect on infection by Salm. enteritidis 857 with slight decreases in Salmonella numbers in the small intestine and large intestine and transient increases in the faeces.

Topics: Animals; Concanavalin A; Feces; Galanthus; Humans; Lectins; Male; Mannose-Binding Lectins; Plant Lectins; Rats; Salmonella enteritidis; Salmonella Infections, Animal; Salmonella typhimurium; Weight Gain

Two groups of 4-5 week old DBA/2J Nii mice were put on either a yogurt-based (n = 33) or a milk-based (n = 32) diet for a period of 4 weeks. At the end of the feeding trial one sub group of mice each from the two dietary groups was sacrificed for assessment of immune response. The remaining mice were challenged intragastrically with 2 x 10(10) live Salmonella typhimurium organisms and continued on their respective diets for 8 days after which they were also sacrificed. The immune response was measured by tritiated thymidine uptake by splenic or intestinal lymphocytes in response to the mitogens concanavalin A (Con A), Phytohaemaggutinin (PHA), and Lipopolysaccharide from Escherichia coli (LPS). Serum Immunoglobulin A levels were also estimated. Feed efficiency, measured as weight gain per unit energy intake, was significantly higher for the yogurt diet than for the milk diet. The mitogenic response of splenic and intestinal lymphocytes in the two groups of unchallenged mice was not different. In the Salmonella-challenged mice the stimulation index (SI) of splenic lymphocytes from yogurt-fed mice (mean +/- SD) was significantly higher (P = 0.001) in response to Con A (24.71 +/- 3.40) than that of milk-fed mice (15.85 +/- 2.09). Further, in these mice the SI of intestinal lymphocytes from yogurt-fed mice was higher than that of milk-fed mice in response to Con A (7.35 +/- 0.61 vs 5.65 +/- 0.78, P = 0.016) and LPS (9.04 +/- 0.93 vs 6.15 +/- 1.32, P = 0.016). Serum IgA levels in Salmonella-challenged mice were significantly higher 8 days after the challenge in the yogurt-fed group than in the milk-fed group (P < 0.001). The experiments indicate an improvement in local gastrointestinal as well as systemic immunity on a yogurt diet as compared to a milk diet.

Topics: Animals; Concanavalin A; Diet; Escherichia coli; Immunoglobulin A; Intestines; Lipopolysaccharides; Lymphocyte Activation; Lymphocytes; Mice; Mice, Inbred DBA; Milk; Phytohemagglutinins; Salmonella Infections, Animal; Salmonella typhimurium; Spleen; Yogurt

The proliferation of murine spleen cells stimulated by a T-cell mitogen such as phytohemagglutinin (PHA) or concanavalin A (ConA) was significantly suppressed when the mice were immunized with either the viable cells or the sonicate of Salmonella typhimurium but not of Escherichia coli. The suppression of T-cell proliferation caused by the sonicate of S. typhimurium was completely restored by addition of phorbol 12-myristate-13-acetate (PMA), an activator of protein kinase C (PKC). Western blots using anti-phosphotyrosine antibodies showed that the mitogen-induced tyrosine phosphorylation of 120-, 106-, 94-, 76-, 68- and 57-kDa proteins in murine splenic T-cells was inhibited in the mice immunized with the viable cells but not the sonicate of S. typhimurium. These results suggest that the inhibition caused by the sonicate involves suppression of PKC activity, whilst that produced by viable cells involves down-regulation of tyrosine phosphorylation, and both inhibitions correlate with the induction of cell-mediated immunity in mice, as evidenced by the induction of delayed-type hypersensitivity reactions.

Topics: Animals; Concanavalin A; Hypersensitivity, Delayed; Immunity, Cellular; Lymphocyte Activation; Male; Mice; Mice, Inbred BALB C; Phosphorylation; Phytohemagglutinins; Protein Kinase C; Salmonella Infections, Animal; Signal Transduction; Spleen; Tetradecanoylphorbol Acetate; Tyrosine

Lymphokines have been shown to affect the resistance of mice to bacterial infections. To explore this effect further, mice were pretreated with 34 units per day for 5 days of a hybridoma supernatant containing primarily interferon-gamma activity. Then, the mice were infected with one LD50 of Salmonella typhimurium strain LT-2. The hybridoma supernatant fluid-treated mice were not protected; in fact, they died faster than did mice only infected with S. typhimurium. When mice were pretreated under the same regimen with pure murine IFN-gamma produced by recombinant DNA technology prior to infection, the mice were protected and 95% survived the infection. The hybridomas had been treated with concanavalin A (ConA) to induce IFN-gamma. When mice were directly treated with ConA prior to infection with S. typhimurium, they also died more quickly than untreated controls. These data suggest that IFN-gamma pretreatment can protect mice against infection with S. typhimurium, but that ConA pretreatment can counteract that effect.

Topics: Animals; Concanavalin A; Female; Interferon-gamma; Mice; Salmonella Infections, Animal; Salmonella typhimurium

Immune mice which exhibited a delayed-type hypersensitivity reaction to bovine serum albumin after bovine serum albumin immunization and stimulation and normal mice that had been transferred with a lymphokine-rich fraction from the supernatant of concanavalin A-stimulated spleen cell cultures demonstrated resistance to Salmonella infection.

Topics: Animals; Concanavalin A; Hypersensitivity, Delayed; Immunization; Liver; Lymphokines; Macrophage-Activating Factors; Macrophages; Mice; Mice, Inbred C57BL; Salmonella Infections, Animal; Salmonella typhimurium; Serum Albumin, Bovine; Spleen