Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.346510
Title: In vitro studies of immune mechanisms in bovine Theileriosis
Author: Musiime, Jotham Tussy
ISNI:       0000 0001 3437 368X
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1983
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Abstract:
This thesis describes studies that were undertaken to evaluate in vitro cell-mediated and humoral immune mechanisms in bovine tropical theileriosis caused by Theileria annulata, and to identify target cells infected by Theileria annulata and Theileria parva sporozoites. Bovine peripheral blood leucocytes (EBL) were fractionated into B-enriched and T-enriched cell populations by nylon wool adherence, plastic surface adherence or E-rosette sedimentation. Evaluation of the infectibility of fractionated cell populations and EBL by Theileria annulata sporozoites in vitro showed that T. annulata selectively infects and establishes in adherent cells, a significant proportion of which exhibit Fc receptors, but these infected cells did not appear to secrete immunoglobulin. Identification of the cell types in T. parva and T. annulata cell lines using immunofluorescence and rosette assays showed that T. parva cell lines exhibited T cell surface markers whereas T. annulata cell lines did not. Moreover, a significant percentage of cells in T. annulata cell lines had Fc receptors indicating that these parasites infect different lymphocyte subpopulations. Optimal conditions for the production of bovine T cell growth factor (TCGP) were established. A combination of Concanavalin A (Con A) and bovine spleen cells yielded more potent TCGP than a combination of Con A and EBL. The TCGP thus produced was used to maintain T cell blasts in culture for about two months. Cell-mediated immune responses in bovine tropical theileriosis were studied using a cell culture technique. This technique allowed for evaluation of cell-mediated responses in an autologous system, in that cultures were initiated in vitro using EBL from an animal before infection and these were later used as targets for effectors from the same individual following infection. Results of this preliminary study showed that cells whose cytotoxicity was restricted to autologous cell lines were generated only in calves that had been successfully infected and immunized against the parasite thus suggesting a role for geneticallyrestricted cytotoxicity in recovery from and immunity to theileriosis. Non-genetically restricted cytotoxic cells were irregularly generated in vitro following initiation and maintenance of an autologous mixed lymphocyte reaction for five days in growth medium. Addition of crude bovine TCGF to this culture system did not enhance the generation of cytotoxic cells. Sporozoite infectivity for bovine lymphocytes in vitro was specifically inhibited by serum taken from cattle hyperimmunized with stabilates of T. annulata sporozoites. There was no synergistic inhibitory effect when sporozoites were exposed to both antisera and PBL from immune calves. It was suggested that immunity against bovine theileriosis is an interplay between humoral and cell-mediated .immune mechanisms. Antibodies may inhibit entry of sporozoites into the host's target cells and their subsequent transformation and cytotoxic cells kill schizont-infected cells.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.346510  DOI: Not available
Keywords: Human anatomy & human histology
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