L'objectif de cette étude était double. Il s'agissait dans un premier temps de caractériser l'immunosuppression produite chez des porcs infectés par une souche de virus influenza H3N2. La deuxième partie de cette étude consistait à tester le potentiel adjuvant d'un dérivé de mannose (l'Acemannan) aux propriétés immunostimulantes. Lors de la première partie de cette étude, les effets d'une infection par le virus influenza furent évalués chez le porc. Il fut démontré par différents essais que la prolifération mitogène-dépendante ainsi que la sous-population de lymphocytes T auxilliaires sont affectées de façon négative lors de ce type d'infection. L'activité des cellules N. K est grandement influencée par le stress des animaux. Dans la deuxième partie de cette étude, les effets de l'Acemannan furent déterminés sur la réponse immunitaire du porc en réponse à un vaccin anti-virus influenza. Ceci a été effectué dans le but de vérifier le potentiel de l'Acemannan comme adjuvant couplé à des vaccins. Ces expériences ont permis de démontrer que l'Acemannan possède des effets activateurs ou inhibiteurs selon le type cellulaire en cause. Des effets activateurs ont été mis en évidence au niveau de la production d'anticorps et de la réponse proliférative des lymphocytes mononucles du sang périphérique du porc (PBML) tandis qu'un effet inhibiteur a été rapporté au niveau de l'activité des cellules N. K. [Résumé abrégé par UMI].

Thèse doctorat : Biochimie : Villeurbanne, INSA : 200. / En annexe, 1 article extrait de la revue "Journal of biological chemistry, vol. 277, n° 42, 18 oct. 2002, p. 39368-39378" Titre provenant de l'écran-titre. Bibliogr. p. 188-221.

No description available.

No description available.

When administered to mice, by various routes, two days before immunization with a tolerogenic dose (10⁹) of sheep red blood cells, the immunosuppressive drug Cyclosporin A (CsA) prevents the suppression of delayed-type hypersensitivity (DTH) reactions. This was observed over a wide range of CsA doses (5-200 mg/kg), given, in a single dose, from a week before immunization to a day after, and with circulating CsA levels ranging below 45 ng/ml at the time of sensitization or challenge. The augmentation of DTH was characterized by induration, intense mononuclear cell infiltration, increased deposition of ¹²⁵I-fibrin within the challenge site and was also reflected in <i>in vitro</i> assays of DTH. Cell transfer experiments showed that the CsA-enhanced DTH could be adoptively transferred to naive recipients, and suggested that CsA may be acting to inhibit a population of Ts cells normally effective during DTH, or to allow T_H/T_DTH cell priming. In addition, an increase in L3T4⁺ cells (T_H/T_DTH) was observed in the CsA-treated mice showing the break in suppression of DTH, suggesting that CsA allowed T_H/T_DTH cell priming. The augmented DTH reactions in CsA-treated mice were accompanied by profound inhibition of the production of splenic IgM antibody-producing cells and circulating anti-SRBC antibody levels. CsA was also shown to increase basal and mitogen-induced splenic macrophage procoagulant activity. These observations indicate that this model could prove useful in separation and study of cell-mediated and humoural immunity. In addition, they have important cautionary implications for the continuing investigation of the clinical potential of CsA.

Pneumocystis is a diverse group of fungi found in the lungs of mammals, and can cause a fatal pneumonia in immunosuppressed humans. The project focussed on two main areas of Pneumocystis biology. The first part investigated the transmission of P. jiroveci between humans and comprised three studies. The first study demonstrated direct transmission between a mother and her infant who had Pneumocystis pneumonia, PCP, contemporaneously. The second investigated transmission of P. jiroveci between health care workers and patients with PCP. P. jiroveci was identified in HCW samples but the genotyping data did not demonstrate direct transmission between the HCW and the patients. The third study examined a representative distribution of P. jiroveci genotypes within a whole human lung and identified two foci of infection. The second main area of research investigated PRT1, a multigene family, encoding a protein with homology to KEX-like proteases. The first part of this study attempted to identify the original single-copy PRT1 gene that encodes the progenitor kexin-like protease. Inconclusive sequence data was obtained. The second part of this study examined regulation of PRT1 gene expression, initially using an assay that characterised the length polymorphisms within the proline rich region of the PRT1 gene. In the complex populations of rat-derived Pneumocystis used it was difficult to distinguish reliable differences between the cDNA (expressed) and genomic DNA proline rich region profiles. Subsequent investigations used simple rat-derived Pneumocystis populations that were derived from inocula of 10 Pneumocystis organisms intratracheally injected into nude rats. The catalytic domain of PRT1 was sequenced from cDNA and genomic copies from each of the five low-dose populations. Two majority sequence types were identified, one genomic and the other cDNA. Three of the populations contained a cDNA majority sequence type, implying that some form of regulation of expression was occurring. This hypothesis was further investigated using a second set of simple populations, hybridisation techniques and 5' RACE.

Bibliography: leaves 206-254. / xiii, 254 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Analyses the cytokine gene expression and the manipulation of these responses in order to offer some insights into the Th1 and Th2 responses associated with allograft rejection. Supports the concept that the unmodified alloimmune response involves complex interactions between Th1-like, Th2-like and APC-derived cytokines. Immunomodulation of the alloimmune response is associated with the down regulation of multiple cytokines within both Th1 and Th2 populations with concurrent upregulation of IL-10 expression. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1998?

Bibliography: leaves 206-254. / xiii, 254 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Analyses the cytokine gene expression and the manipulation of these responses in order to offer some insights into the Th1 and Th2 responses associated with allograft rejection. Supports the concept that the unmodified alloimmune response involves complex interactions between Th1-like, Th2-like and APC-derived cytokines. Immunomodulation of the alloimmune response is associated with the down regulation of multiple cytokines within both Th1 and Th2 populations with concurrent upregulation of IL-10 expression. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1998?

Thesis (Ph. D.)--University of Adelaide, Dept. of Medicine, 1991. / Includes bibliographical references (leaves 234-314).

Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1998? / Bibliography: leaves 206-254.