Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 62-69). / viii, 69 leaves, bound ill. 29 cm

An in vitro IgG secretion assay was developed to investigate the regulation of the humoral immune response in humans. Pokeweed mitogen (PWM), a plant lectin derived from Phytolacca americana stimulates human peripheral blood mononuclear cells (PBMNC) to divide and resting B-lymphocytes to differentiate into immunoglobulin secreting cells (ISC). This differentiation requires that both monocytes and T-lymphocytes be present in the culture system. The amount of IgG secreted by these differentiated B-lymphocytes in response to PWM appears to be the net result of a balance between the functional activity of the regulatory T-helper and T-suppressor cells. Alterations, qualitative or quantitative in any of these leukocyte subsets could conceivably alter the amount of IgG secreted by the B-lymphocyte subpopulation. We have employed this assay to investigate the immune status in a group of chronic progressive multiple sclerosis (MS) patients and to assess the immunoregulatory effects of interferon (Wellferon R, INF) administered in vivo to this selected group. Their mononuclear cells (MNC) were studied in this PWM induced IgG secretion assay before INF treatment and again after 7 days of daily sub-cutaneous injections (5 X 10⁶ u/day). Twenty patients received the interferon (INF) preparation and eighteen received normal saline. The study was carried out in a double blind manner and the code was broken only after individual results had been calculated. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

[Truncated abstract] Hepatic progenitor cells (HPC) are becoming increasingly recognized as facultative stem cells capable of regenerating the liver during chronic liver injury and also as targets of malignant transformation. Similar markers are expressed by hepatocellular carcinoma (HCC) and HPC, and a precursor-product relationship is well established. This thesis focuses on the ways in which the HPC population can be controlled under circumstances of chronic liver injury, and in this manner, reduce the risk of progression to HCC reduced. The major aim of Chapters 3 to 5 was to elucidate the effect of interferon α (IFNα) therapy on HPC. Chronic hepatitis C affects approximately 250 million individuals world wide. Approximately 80% of infections progress to chronicity, which places the individuals at greater risk of developing HCC. The gold standard of treatment of chronic hepatitis C is a combination of pegylated IFNα and ribavirin. ...The results were surprising. While IFNγ exerted a pro-apoptotic and antiproliferative effect on HPC in vitro, administration of IFNγ to CDE-fed mice for 14 days increased fibrosis, enhanced inflammatory infiltration and exacerbated the HPC response, with concurrent hepatocyte cell death. In addition, increased morbidity and mortality were observed in the IFNγ-treated mice compared to control. IFNγ treatment was found to prime the liver for the HPC response by recruiting inflammatory cells and altering the hepatic cytokine profile, both of which may facilitate an increased HPC response. Numbers of activated HSC were also increased in the IFNγ-treated, CDE-fed mice, correlating with the increased fibrosis seen in these animals. This data contradicts the current experimental use of IFNγ for treatment of fibrosis. Based on our results, we suggest that IFNγ promotes HPC proliferation in the CDE model, by encouraging inflammatory infiltration and hepatocyte damage and this initiates pro-fibrotic events. Concurrent proliferation of HPC and activated HSC further supports the view that there is a close relationship between the two cell types, and thus, a link between the HPC response and fibrosis. In conclusion, findings documented in this thesis suggest that administration of IFNα and IFNγ can contribute to shaping the HPC response. IFNα therapy may reduce HCC risk in chronic hepatitis C patients by bringing the HPC population under control. In contrast, IFNγ treatment can exacerbate the HPC response, liver fibrosis and parenchymal damage, illustrating the need to approach this method of fibrosis treatment with caution.

Mycobacterium bovis is the causative agent of bovine tuberculosis (BTB) which has a diverse host range. The maintenance host of BTB in South Africa is the African buffalo (Syncerus caffer). It is believed that lions get infected by feeding on infected buffalo or through wounds. The spread of the disease amongst lions has raised concern regarding the future of the animals and the impact on tourism in the country. Diagnoses of tuberculosis in free ranging wildlife is often dependent on post-mortem samples due to logistical challenges, the use of the lion specific interferon gamma release assay as an antemortem test offers a simpler methodology to testing live animals. The aim was to optimise an already developed assay by Maas et al.,2012 and to harmonise it with the Rhinoceros specific interferon gamma assay developed by Morar-Leather et al 2007. Optimisation of the interferon gamma specific ELISA included: determination of optimal concentrations for the capture and detection monoclonal antibodies; optimal concentrations for the conjugate and evaluation of alternative blocking agents. Different mitogens and incubation times were evaluated for the stimulation of whole blood as positive control in the assay. The optimum concentration for coating the plates with the capture monoclonal antibody was 2 g/ml. An optimum dilution of 1:5000 was selected for both the biotinylated detection monoclonal antibody and the streptavidin horseradish peroxidase conjugate. The assay was optimised using recombinant lion interferon gamma and the lower detection limit was calculated to be 109 pg/ml. Phosphate buffered saline with 1% bovine serum albumin was found to be Chapter 1 © University of South Africa iii a suitable blocking agent. Native interferon gamma was detected in whole blood samples from 5 lions and a 24 hour incubation time with PMA and ionomycin was selected as the optimal mitogen positive control. This assay system demonstrated good potential as an ante mortem test for the diagnosis of tuberculosis in lions. In conclusion, the assay can detect IFN- from supernatants harvested from whole blood cultures stimulated with specific antigens and mitogens / Agriculture and  Animal Health / M. Sc. (Agriculture)