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At least 379 records · Page 21Linked to original sources
PubMed1994

Accessory cell signals regulate Th-cell responses: from basic immunology to a model of helminthic disease.

Schistosome helminths inflict serious tissue damage by eliciting T helper (Th)-cell-mediated granulomatous inflammation around parasite eggs. The egg granulomas are large in acute disease and smaller in chronic disease. To explain this downregulation in chronic disease, Miguel Stadecker and Pedro Flores Villanueva describe a mechanism whereby CD4+ Th1-type lymphocytes, which are associated with the initial vigorous granuloma formation, are rendered anergic to subsequent antigenic stimulation. This results in the reduction of granuloma size and in the dominance of Th2-type lymphocyte responses.

Animals↗
PubMed1975

Burkitt's lymphoma - a human tumor model system for immunological studies.

Burkitt's lymphoma occurs mainly in parts of tropical Africa and has attracted the attention of experimental workers due to its epidemiological and clinical features, which indicate a viral etiology and a host immune response to the tumor. As a result of virological studies, Epstein-Barr virus (EBV) DNA has been demonstrated in almost all tested biopsies of African BL. This contrasts to the absence of EBV in all, or almost all, of the non-African Burkitt's lymphoma-like tumors, even though the number of tested tumors in this group is small, and to the lack of EBV in all other types of lymphoma or leukemia. Immunological studies have revealed the presence of antibodies to different EBV-associated antigens in all African patients with Burkitt's lymphoma. However the antibodies are not specific for Burkitt's lymphoma but are found in most adults all over the world, although at lower levels. They cannot therefore serve diagnostic purposes, but they can give prognostic information and occasionally give clues to the mechanisms behind late tumor recurrences, and possibly guide so-called immunotherapy. Burkitt's lymphoma patients contrast to appropriate control groups where some of the persons are anti-EBV seronegative, and this, together with the presence of EBV in Burkitt's lymphoma biopsies and the absence of EBV in other lymphomas, even though the cell type involved may be infectable by EBV in vitro and the tumor may arise in an EBV-carrying person, favors an etiological role in EBV in Burkitt's lymphoma and speaks against the "passenger" hypothesis, according to which EBV is picked up by the Burkitt's lymphoma cell which happens to be particularly suitable for EBV persistence. To explain the geographical distribution, a cofactor, such as certain forms of malaria, has been implied.

Adolescent↗
PubMed1998

A viro-psycho-immunological disease-model of a subtype affective disorder.

Borna Disease Virus (BDV) infections are widespread in animal species. This neurotropic, negative and single-stranded enveloped RNA virus spreads via axonal and transsynaptic pathways quite specifically into olfactoric and limbic structures. The symptoms in BDV-infected animals range from unapparent or subtle clinical manifestations to fatal neurological disorders. The severe and fulminant course of the infection, which is often accompanied by neurobehavioral and "emotional" disturbances, occurs sporadically and, at least in experimentally infected animals (rats), is thought to be mediated by immunopathology. Increases in serum-BDV antibodies have also been detected in neuropsychiatric patients. In addition, viral antigen and viral RNA have been observed in acutely ill major depressive patients, leading to the conclusion that BDV was causally related to psychiatric disorders, in particular to affective disorders. A number of studies have meanwhile furnished evidence of abnormal immune functions in mentally ill patients. In addition, stress has been shown to decrease immune responses to viral infections. On the basis of these findings it is hypothesized that human BDV infection represents a co-factor in the development or course of psychiatric diseases. Stress may cause immunosuppression and thus induce activation of persisting BDV in the limbic system, resulting in an inflammatory reaction of these structures. These neuropathological changes might influence the serotonergic or dopaminergic neurotransmitter systems. In addition, a specific affinity of BDV structural elements for aspartate and glutamate receptors in the hippocampal formation might directly induce an imbalance of these transmitter system interactions, causing affective and behavioral disturbances. The possible interactions between stress-induced immunosuppression, BDV infection and affective disorders in humans, and the theoretical and clinical aspects of this concept are discussed.

Animals↗
PubMed1999

Studies on an immunologically induced synovitis model in pigs and sheep.

Chronic synovitis was induced in seven sheep and nine pigs to investigate the potential applicability of laser treatment in arthroscopic synovectomy. Systemic sensitization was accomplished using chicken egg or turkey egg albumin antigens with Freund's incomplete adjuvant, enriched with killed and dried Mycobacterium tuberculosis. Ten days after the second immunizing dose, skin sensitization testing was undertaken. After a satisfactory systemic reaction had been observed, the respective antigen was injected once or twice into the left knee of each animal at 2-week intervals. After chicken egg albumin sensitization at varying systemic immunization and joint injection doses, sheep (five of five) showed neither strong morphologic nor continuous synovitis, despite a positive systemic reaction. In pigs (three of three) the inflammatory signs also were unsatisfactory for the manifestation and characterization of a synovitis model. In contrast, the application of turkey egg albumin to pigs (six of six) during the 4-month study provided a persistent, clearly manifested synovitis that developed visible villi formation and an amber to gray synovial fluid and microscopically showed follicular aggregations of lymphocytes and plasma cells. In similarly immunized sheep (two of two), only a light synovitis developed with occasional perivascular inflammatory foci.

Animals↗
PubMed1975

[Halo Nevus (Morbus Sutton): model of an immunological tumor regression].

Spontaneous regressions of malignant tumors are rare in the history of malignant disease. In malignant melanoma immunological mechanisms were accounted for the regressions observed. By the clinical phenomenon called Halo nevus a benign pigment-cell-tumor is described which shows spontaneous involution. The characteristic feature is the depigmentation of the surrounding uninvolved skin and a centripetal progression of the tumor-regression-phenomenon. In the present study it is demonstrated by histopathological and immunological investigations that lymphocytes are responsible for this tumor-regression. Lymphocyte-reactivity of 16 patients with Sutton's disease in different stages were investigated in the microcytotoxicity-assay against culture-grown melanomatargetcells. In 11 patients a specific cell-mediated immunity against the melanoma cells could be demonstrated in vitro. 5 patients did not show any reactivity, the Halo nevus had been removed by surgery 2 years earlier. The results of the immunological assay are confirmed by histopathological light- and electron-microscopic incestigations and documented by typical examples.

Adult↗
PubMed1992

Study on the mechanism of an experimental immunological intrahepatic cholestasis model.

Tuberculin-sensitized guinea pigs were intravenously injected with heat-killed Propionibacterium acnes followed by an intravenous injection of purified protein derivatives 7 day later, resulting in the induction of intrahepatic cholestasis. Using this experimental model, the following results were obtained: (1) Both uptake and release of bile acid were inhibited in the hepatocytes prepared from the cholestasis guinea pigs. (2) The results of the erythritol clearance method indicated that the decrease in bile flow observed in the cholestasis guinea pigs was mostly attributable to the reduced bile excretion from the canaliculi. (3) The decrease in the formation of bile acid independent bile flow was the cause of the decrease in bile flow observed in the cholestasis guinea pigs. (4) There was no change in the permeability of the interhepatocellular tight junction in the cholestasis guinea pigs.

Animals↗
PubMed1979

Comparison of the effects of a non-steroidal anti-inflammatory agent, an immunosuppressive, a corticosteroid and an immunomodulator on various immunological and non-immunological inflammatory experimental models.

The effects of a non-steroidal anti-inflammatory agent, phenylbutazone, a corticosteroid, desonide, an immunosuppressive, cyclophosphamide and an immunomodulator, levamisole on a number of experimental inflammatory models were compared. Compounds were first tested in carrageenin-induced pleurisy as a non-immune acute inflammation, then in passive skin anaphylaxis and reversed passive Arthus oedema in the rat as models of humoral immunity. Finally the compounds were investigated in various delayed hypersensitivity tests: reaction to sheep red cells and to oxazolone in the mouse, skin reaction to purified protein derivative (P.P.D.) in the rat and guinea-pig, P.P.D. induced pleurisy in the guinea-pig.

Animals↗
PubMed1989

Enhancement of inflammatory reactions in a non-immunological air pouch model in rats.

In a carboxymethyl cellulose (CMC) air pouch inflammation model, accumulation of exudate decreased at a relatively rapid rate and almost disappeared 3 days after a 2% CMC injection into the preformed air pouch. After a second injection of 2% CMC solution into the 1-day-old CMC pouch on the day following the first CMC injection, the decrease in rate of exudate was similar to the change seen after the first CMC injection. In another group of rats, 3 days after the first CMC injection when inflammation had subsided, a second injection of 2% CMC solution into the 3-day-old CMC pouch resulted in a marked increase of exudate accumulation, inflammatory cell infiltration and vascular permeability. Histologically, large numbers of macrophages accumulated in the 3-day-old CMC pouch and fibroblast proliferation and newly formed blood vessels were also visible. The enhanced exudative reaction was significantly inhibited by dexamethasone but not by indomethacin. These results indicate that the enhanced inflammatory reactions appear to be closely correlated with the increase of reactivity at the site of inflammation and the exudative reaction was not mediated by cyclo-oxygenase products.

Acute Disease↗
PubMed1987

Morphometric quantitation of histopathologic changes in articular cartilage in an immunologically-induced rabbit model of rheumatoid arthritis.

An immune arthropathy was induced in New Zealand white rabbits by intradermal sensitization with complete Freund's adjuvant containing Mycobacterium butyricum followed by intra-articular administration of the bacterial antigen. Half of the animals were treated with 1 mg/kg/day of prednisolone sodium phosphate for 8 weeks by gavage beginning with the day of intra-articular challenge, while the remaining rabbits received the drug vehicle alone. By morphometric analysis (matrix/chondrocyte lacunae area ratio), we observed a significant decrease in cellularity in the arthritic articular cartilages from the vehicle control group. By contrast, there was a significant increase in cellularity in the patella, femoral and tibial cartilages of the steroid-treated animals as compared with that observed in the contralateral control joint. This study suggests that image analysis provides a reliable means for evaluation of architectural changes in the articular cartilage and allows for meaningful quantitation of the chondroprotective effects of drugs like prednisolone.

Animals↗
PubMed2006

Integrative models of bat rabies immunology, epizootiology and disease demography.

Bats are natural reservoirs of rabies. We address the maintenance of the disease in bat colonies by developing individual and population models that generate indicators of risk of rabies to bats, that provide dynamic estimates of effects of rabies on population densities, and that suggest consequences of viral exposures and infections in bats relative to physiological and ecological characteristics of bats in different habitats. We present individual models (within host) for the immune responses to a rabies virus challenge, an immunotypic disease model that describes the evolution of the disease and a disease demographics model, which is structured by immunotypic response governed by immune system efficiency. Model simulations are consistent with available data, characterized by relatively low prevalence of the virus in colonies and much higher prevalence of rabies virus-neutralizing antibodies. Under model conditions, there is a robust non-clinical state that can be attained by the exposed individual that allows persistence of the disease in the population.

Animals↗
PubMed2002

[Experimental study on liver protective effect of Artemisia rupestris extract].

OBJECTIVE: To explore the protective effect of Artemisia rupestris extract (ARE) on chemical liver injury and immunological hepatitis. METHODS: Mice model of immunological hepatitis was established by lipopolysaccharide plus Bacillus Calmette-Guérin vaccine (BCG), and the models of liver injury was induced by D-galactosamine or carbon tetrachloride (CCl4) in mice and rats. The effects of ARE in preventing and treating immunological hepatitis and protecting liver injury were observed. RESULTS: ARE significantly lowered the serum alanine transaminase (ALT) in immunological hepatitis (P < 0.05), CCl4 induced liver injury model mice and rats (P < 0.01), and in D-galactosamine induced liver injury mice (P < 0.05). CONCLUSION: ARE has significantly protective effect against chemical liver injury and could treat immunological hepatitis, but with no effect in preventing immunological hepatitis. These might be the partial pharmacologic basis for using ARE in treating hepatitis.

Animals↗