Professional antigen presenting cells (pAPCs) process and present antigens on their cell surface in association with MHC class I molecules through two general pathways: direct or cross-presentation. The process of antigen presentation by pAPCs to naïve T cells resulting in their proliferation and differentiation into activated cytotoxic lymphocytes (CTLs) is called T cell priming. In these studies, we examine the cross-presentation of antigens from two non-replicating viruses: inactivated Lymphocytic Choriomeningitis virus (LCMV), and recombinant baculovirus encoding the LCMV nucleoprotein (NP). Since effective activation of pAPCs is essential for efficient priming of CD8+ T cells and CTL activation, and because infection with inactivated viruses generally induces an extremely poor level of CTL activation, we examined the activation state of pAPCs by measuring their cytokine profiles following infection to help further delineate their involvement in the CTL response to inactivated viruses. Our results indicate a pro-inflammatory cytokine mRNA upregulation in pAPCs in response to the inactivated virus, similar to the cytokine profiles subsequent to live LCMV infection, but to a lesser extent. In these studies, we also examined CTL activation following infection with inactivated LCMV and bAc-NP. We have demonstrated that the presentation of antigens from inactivated LCMV and bAC-NP results in a low level of CTL activation in vivo, though there is an undetectable level of CTL activation in vitro, in comparison to activation following infection with the live virus. Ultimately, the characterization of the cytokine profiles of pAPCs and the CD8+ T cell profiles induced in response to inactivated LCMV or the baculovirus derived NP may lead to a better understanding of how cross-presentation of these viral antigens may occur. This information may be applied to enhance the process of pAPC activation and T cell priming, for the induction of more effective cellular immune responses and the generation of stronger protective immunity. / Thesis (Master, Microbiology & Immunology) -- Queen's University, 2009-09-02 15:30:13.883

Four experiments were conducted to evaluate effects of arginine (ARG), vitamin E (VE) and mannanoligosaccharide (MOS) on immune response and clearance of Salmonella in broiler chickens. There were 4 groups in Exp.1 (E.1) and E.2: antibiotic-free diet (CTL-); diet with antibiotic (CTL+); ARG and VE (AVE); ARG, VE and MOS (AVM). Birds were infected with 10^6 CFU/ml of a novobiocin and nalidixic acid resistant Salmonella enteric Serovar Typhimurium (ST) at d 7 (E.1) or at d 3 (E.2). In E.3 and E.4, there were three groups: CTL, AVE and AVM; at d 3, birds in E.3 were infected with 10^2 CFU/ml ST and birds in E.4 were infected with 10^6 CFU/ml ST. The following were analyzed for four experiments: Oxidative burst heterophils response (OBHR) and monocytes response (OBMR); Lymphocyte proliferative response (LP); antibodies concentrations in serum; chicken body weight (BW), cecal Salmonella concentration; gut parameters. In E.1, both AVM and AVE diet decreased OBHR; birds fed AVM showed the highest IgA level, birds fed AVM had higher IgM than CTL+ and had the lowest Salmonella population. Birds fed AVE showed higher LP than CTL- in E.1 and E.2. From E.1 and E.2, AVM decreased chicken innate immune response at a younger age and improved adaptive immune response when birds were older than 16 d. AVM reduced ST when administrated later (d 7) versus early (d 3). In E.3, no BW and Salmonella counts differences were found; birds fed AVM had a higher IgA than AVE but similar to CTL at d 17. Chickens fed CTL had the highest OBHR at d 17, chickens fed AVM had the highest LPR at d 17. In E.4, chickens fed AVM showed higher BW than CTL at d 17 and d 24. Also no Salmonella counts differences were found. Chickens fed AVE had higher LPR than chickens fed AVM at d 17. These results are consistent with results from E.1 and E.2. Overall, diet AVM has different effects on chicken immune response when chicks were infected at different age; higher level of ARG and VE improved immune response and improve gut health.

In this study we have reproduced the prolongation of graft survival by ITI in a rat heart transplant model in which an ITI of an optimal number of donor bone-marrow cells (BMC) was given together with 1ml ALS IP 14 days before transplant. The efficacy of this protocol was critically dependent on the donor-recipient haplotype and influenced by antigenic strength and MHC disparity but not by non-MHC background genes. In strain disparities where ITI was unsuccessful, this was caused by alloreactive recent thymic emigrant cells. In a high responder strain combination the effect was highly dependent on the dose of BMC in the intrathymic injection. Moreover it was readily reproduced with injection of antigen by the intravenous route, even at a lower dose than that required via the intrathymic route. This was in contrast to the other strain combinations tested in which the beneficial effect of donor antigen injection was specific to the intrathymic route, and it suggested that the effect in this group might be at least partly dependent on peripheral mechanisms. The polyclonal ALS can easily be demonstrated to be non-specific in its depletion of peripheral lymphocytes at the dose used in these studies, and we have shown that it also penetrates the thymus. Therefore treatment with ALS may have more effects that mere disablement of peripheral alloreactive T cells, thus complicating the interpretation of the experiments. We have therefore refined our model by recruiting in place of ALS a more specific agent, the partially depleting anti-CD4 monoclonal antibody MRC-OX38, which is equally effective as an adjunct to ITI. We have shown using flow cytometry and immunohistochemistry, that this and certain other monoclonal antibodies, at a therapeutic dose, do not cross the "blood-thymus barrier", and therefore do not complicate the model as ALS potentially does. We would recommend this approach in further studies.

No description available.

Prophylactic administration of the immunosuppressive drug cyclosporine A protects Balb/c mice from fatal Leishmania major infections. It is believed that distinct subpopulations of CD4+ T lymphocytes and their distinctive cytokines may determine susceptibility and resistance to leishmaniasis among inbred strains of mice. CsA may enhance disease resistance in Balb/c mice by modulating these T cell subsets and/or their cytokines. We have measured lymphoid cell production of IL-2, IL-4, and TNF-a in naturally resistant C57/Bl/6, CsA-treated Balb/c, and nontreated Balb/c mice during the course of L. major infection. CsA treatment inhibited IL-2 and IL-4 production for the first week of infection. Thereafter the cytokine production of all three groups of mice did not differ greatly except in week two when the treated mice produced significantly enhanced levels of IL-4. C57B1/6 mice did produce slightly more TNF-a than either group of Balb/c mice, but as the CsAprotected and diseased Balb/c mice produced similar amounts of this cytokine, the elevation in C57B1/6 animals probably reflects a strain-related difference rather than disease resistance. / Department of Biology

If used early in infection, prophylactic treatment with the immunomodulatory drug cyclosporin A of Leishmania ma'or infected Balb/c mice has been shown to enhance resistance of these mice to serious disease. It is thought that CsA treatment affects disease progression by altering the balance of specific T lymphocyte populations as well as the secretion of various cytokines. We have followed the levels of L3T4+ T cells, Ly-2+ T cells, and total T and B lymphocytes, as well as IL-4 in susceptible Balb/c mice, CsA-treated Balb/c mice, and naturally resistant C57B1/6 mice during the course of L. ma'or infection. The CsA-treated mice displayed a disease pattern similar to that of the C57B1/6 group throughout infection. Most importantly, CsA treatment appeared to inhibit IL-4 production early post infection in both spleen and lymph node, and also appeared to inhibit the dramatic early increase of L3T4+ (CD4+) T cells which is characteristic of the susceptible Balb/c mice. / Department of Biology

No description available.

The complement system is considered as the chief recognition and effector component of innate immunity; it is involved in inflammation and enhances the adaptive immune response. Factor I (fI) is a heterodimeric serine protease consisting of a heavy (HC) and a light-catalytic (LC) chain; it circulates in an active form regulating complement by selectively cleaving only C3b or C4b in the presence of a cofactor such as factor H (fH), CR1, MCP or C4bp. The cleavage of C3b occurs through a ternary complex formed between fI, C3b and a cofactor like fH and yields iC3b, a major opsonin. The structural and functional properties of fI were investigated. The interchain disulphide bond formed between C³⁰⁹-C⁴³⁵ tnat links the HC and LC of fI as well as the composition of the TV-linked carbohydrates of fI were determined. By using two independent assays, the proteolytic and amidolytic assays, the catalytic properties of human fI were characterised in detail. The catalytic subunit, the SP domain, was shown to have a native conformation that accommodates substrate recognition and cleavage, fI has specificity similar to thrombin, but exhibits lower catalytic activity. fI amidolytic activity reaches optimum at pH 8.25 and is insensitive to ionic strength. This is in contrast to its proteolytic activity within the fI-C3b-fH reaction, in which the pH optimum for C3b cleavage is <5.5 and the reaction rate is highly dependent on ionic strength. The rate of cleavage of tripeptide AMC substrates by fI was unaffected by fH or C3(NH₃) at optimum pH. fI and the isolated SP domain were found to have similar amidolytic activities, but strikingly different proteolytic activities on C3(NH 3 ). fl did not cleave C3(NH₃) in the absence of fH, but cleaved it rapidly at two sites in its presence. The SP domain however, cleaved C3(NH₃) slowly in the absence of fH, at more than two sites. Cleavage by the SP domain was inhibited, not stimulated, by fH. These results suggested that the HC domains and/or the cofactor must orient the natural substrates and restrict cleavage by fI to the two sites which yield iC3b. The implications of these findings are discussed.

Mutations in the p53 gene are known to be associated with a wide range of human tumors. In some primary tumors and established cell lines, stable mutant p53 protein is expressed at high levels, whereas, in normal cells unstable wild-type p53 protein is expressed at very low levels. Sera from some patients with breast and colon tumors contain anti-p53 antibodies. It is unclear whether changes in p53 structure, or its increased level in tumors, causes p53 to become antigenic. In our study we tested sera from patients with various types of cancer for anti-p53 antibodies. Examination of the sera was made by Western blot, and the results were confirmed by rescreening sera with immunoprecipitation. Both techniques revealed the presence of anti-p53 antibodies in some sera from lung and ovary cancer patients, as well as in the sera from patients with breast or colon cancers. Clearly, patients with various cancer tumors are able to produce anti-p53 antibodies. It was unclear whether this humoral immune response is against mutant or wild type p53. To provide a better definition of this immune response, we have examined the anti-p53 response from cancer patients against mutant and wild type p53 in the native and denaturated state. Western blot and Immunoprecipitation analysis showed that the anti-p53 sera recognise both wild type and mutant p53 conformational and denaturation resistant epitopes. Taken together, these data demonstrate that the mutant p53 is not more antigenic than the wild type p53. This provides strong evidence that the antibody response is not directed solely against the altered conformation in mutant p53.

Typescript (photocopy) / 132 leaves, [2] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology and Immunology, 1982