<I>Theileria annulata</I>, a protozoan parasite, causes a lymphoproliferative disease of cattle known as tropical theileriosis. This disease is a serious constraint to the improvement of indigenous cattle using crossbreeding in developing countries and is usually fatal in exotic and cross-bred animals if not treated. <I>T. annulata</I> infected tissue culture cell lines are used as a vaccine in most parts of the affected world. The draining lymph node (DLN) is believed to be the site for immune responses but the mechanism of responses in the DLN and afferent lymph was unknown when this work began. This thesis set out to investigate responses in the DLN and afferent lymph after cell line immunisation by immunohistological, cytokine and pseudoafferent cannulation studies. Immune responses in the DLN were examined by immunohistological and reverse transcription polymerase chain reaction (RT-PCR of cytokines) methods. Initial activation of T cells was observed in the paracortex (the normal anatomical site for activation) by day 4 after immunisation. Primary follicles (PF) were observed by day 4, developed germinal centres (GC) by day 12 which increased in size and number by day 16. A high, 1:10240, schizont serum antibody titer was recorded on day 16. A few T cells (T cells are critically important for GC formation) were observed in the PF. These increased by day 16 when well developed GCs were observed. Similarly, a few proliferating cells were noticed in PF by day 4. These had increased by day 9 and were numerous by day 16, by which time PF had became large GCs. VPM30<SUP>+</SUP> cells were found in the light zone in GCs on day 16 only. This molecule is expressed on differentiated B cells in the GC. Schizonts were observed in CD 11b<SUP>+</SUP> cells, this molecule is expressed upon monocyte/macrophages and granulocytes. Proliferating cells were observed by day 4 in the paracortex and by day 9 & 16 in the medulla. Results presented in this thesis showed that a normal immune response developed in the DLN with T cell activation and formation of GCs following cell line immunisation. Cytokine studies showed production of IFNγ followed by IL-4. This was in complete contrast to studies by other workers on lethal sporozoite infections where GCs were lost and only IFNγ was detected. It seemed as if the production of both IFNγ and IL-4 by T cells could serve as a marker for cell lines of low virulence. Cannulation studies indicated DLN to be the site of parasite transfer and showed: the circulation of naive T cells through the afferent lymphatics, the site of immunisation as the initial T cell activation site and NK-like activity at the site of immunisation.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:651558 |
| Date | January 1996 |
| Creators | Goel, Parveen |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13927 |
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