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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/14944
Title: The Study of Lymphocyte Responsiveness and Mycobacterium Tuberculosis DNA in Peripheral Blood of Patients with Pulmonary Tuberculosis
???metadata.dc.contributor.*???: Dr. Robert Mshana
Dr. Sally Cowley
Dr. Endashaw Bekele
Gelaw, Muluget
Issue Date: Jun-1996
Publisher: Addis Ababa University
Abstract: In vitro responses of T cells from tuberculosis patients to mycobacterial antigens are sometimes suppressed. This effect has been observed to be specific for PPD (purified protein derivative) and does not affect the response to other antigens. Several factors have been suggested to be responsible, such as abnormalities in IL-2 production and secretion of IL-I0 and TGF-{3 by suppressor monocytes. However, whether any of these factors and the systemic lymphocyte hyporesponsiveness observed in some pulmonary TB patients relates to exposure of circulating monocytes to mycobacteria and its products is unknown. In this study the relationship between antigen-specific hyporesponsiveness and the presence of mycobacterial DNA in blood circulation was examined by comparing lymphocyte responsiveness with the presence of M. tuberculosis• DNA in blood samples of 30 smear positive, untreated pulmonary TB patients. The study also aimed at investigating the potential of PCR as a diagnostic tool for TB using peripheral blood of pulmonary tuberculosis patients. Six of the patients were unresponsive to PPD, all (n =30) showing a positive PCR signal in peripheral blood, and 5 of them being HIV (human immunodeficiency virus) seropositive females below 38 years of age. Classifying patients in decreasing order for PPD response, showed that 12 patients out of the total of 16 PCR positive patients belonged to the group of 15 patients that showed the lowest responses to PPD, and conversely, 11 of those patients who were PCR negative belonged to the group of 15 patients with the highest responses to PPD (r =-0.502, P = 0.005, Spearman rank order correlation). A positive relationship was also found between the lymphocyte response from PPD-unresponsive individuals and the disease status classified radiologically. Five of the six PPD-unresponsive patients showed more extensive disease radiographically, two with moderate and three with far advanced disease in the lungs. Out of the 30 patients diagnosed (using direct microscopy and culture) to have pulmonary TB, 16 (53.3%) were found to be positive in the IS611O-based nested PCR using peripheral blood. Out of these, 12 (75%) were HIV positive patients. Out of 13 HIV and TB coinfected patients, PCR was positive in 12 (92.3%) while only 4 (23.5%) out of 17 HIV negative TB patients were PCR positive. Irrespective of the fact that patients were selected for this study based on smear positivity, comparison with smear and culture showed that IS6/ /0-based nested PCR from peripheral blood is less sensitive especially for HIV negative patients than these standard laboratory diagnostic procedures. However, the technique may have potential for diagnosis of TB in HIV positive patients, and may have merit as a research tool for measuring mycobacterial DNA in peripheral blood.
Description: A Thesis Submitted to the School of Graduate Studies Addis Ababa University in Partial Fulfillment of the Requirement for the Degree of Master of Science in Biology
URI: http://hdl.handle.net/123456789/14944
Appears in Collections:Thesis - Biology

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