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Title: Trypanosoma (Nannomonas) congolense : pathogenesis and cellular responses in the early stages of infection in sheep
Author: Mwangi, D. M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1992
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Cellular responses and parasites kinetics associated with the development of local skin reactions were examined in sheep following infection with metacyclic forms of Trypanosoma (Nannomonas) congolense. Leucocyte phenotypes in the skin and regional draining lymph nodes were examined by indirect immunoperoxidase staining using monoclonal antibodies specific for ovine leucocyte subsets. Immunofluorescence and flow cytometry was used to determine changes in the numbers and proportions of different cell phenotypes in peripheral blood and in lymph from cannulated afferent and efferent lymphatic ducts draining both the skin reaction and regional nodes respectively. Cellular reactions occurring in the skin prior to development of local skin reactions were investigated by light and transmission electron microscopy. Trypanosomes were observed in the skin during the first four days of infection. Following development of the local skin reaction, and histological demonstration of trypanosomes in the skin and draining lymph nodes five to seven days after infection, large numbers of parasites appeared in the afferent lymph, reaching peak numbers seven to 10 days after infection. During this period, trypanosomes were also present in the efferent lymph. Trypanosomes were not detectable in skin or draining lymph nodes after 13 days but persisted at a low level in both afferent and efferent lymph. Parasites did not appear in peripheral blood until 15 days after infection. Cellular responses varied according to the stage of development of local skin reactions and the presence of trypanosomes in the various compartments. Prior to development of local skin reactions, the only cellular event observed histologically by transmission electron microscopy was evidence of mast cell degranulation. Local skin reactions developed at inoculation sites of sheep from day five after infection and were initially characterized by an infiltrate of mononuclear cells and neutrophils. Mononuclear cell infiltrate comprised equal proportions of T cells (CD5+ , CD4+ and CD8+ ) and B cells (CD45R+ ), MHC Class II+ cells and macrophages. B cells and MHC Class II+ cells were found mainly in aggregates, suggesting local proliferation and antibody production. There was a greater proportion of CD4+ cells than CD8+ cells, but SBU-T19+ (τdelta T cells) were rarely present.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available