Date of Award

1988

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Animal Science (Animal, Dairy, and Poultry Sciences)

First Advisor

Theron G. Snider, III

Abstract

Cattle, naturally infected with Mycobacterium paratuberculosis, were evaluated with respect to immune status. Their ability to express cell mediated immune responses to homologous and heterologous antigens was also evaluated. Lymphocyte and macrophage augmentation was attempted to localize the immune defect in cattle with paratuberculosis. Infected cattle had varying responses to johnin skin test antigen. Lymphocyte blastogenic responses and migration inhibition were, however, consistently positive in infected cattle. Non-infected cattle had positive skin test reactions, blastogenic responses, and migration inhibition after sensitization with M. bovis BCG, M. paratuberculosis, and keyhole limpet hemocyanin. No changes were seen in lymphocyte blastogenic response, migration inhibition, interleukin-2 production, and interleukin-1 release in infected cattle after sensitization. Rifabutin treatment increased cutaneous hypersensitivity of johnin skin test antigen. No lesion alterations were induced with this antimicrobial agent. Preliminary evidence indicated that blood monocytes phagocytize bacteria and take up ferritin. It could not be accurately determined if killing of the organism had taken place. The ferritin was seen in round clumps suggestive of secondary lysosomes and as small grains in association with bacteria. This may have represented phagosome-lysosome fusion. Interleukin-2 production was decreased in infected cattle from that in non-infected controls. Non-infected cattle significantly increased interleukin-2 production in response to sensitizing antigens while no effect was seen in the infected animals. Transfer factor specific for M. paratuberculosis and keyhole limpet hemocyanin augmented cell-mediated responses in infected cattle as evidenced by positive migration inhibition and increased interleukin-2 production. No alterations in ileal and mesenteric lymph node lesions were noted after transfer factor treatment. Blood monocytes from infected cattle spontaneously released high levels of interleukin-1 and increased release with bacterial lipopolysaccharide stimulation. Non-infected cattle released significant levels with keyhole limpet hemocyanin, M. bovis PPD, and johnin with the highest release occurring with johnin stimulation. Interleukin-1 release was not affected by sensitization with M. bovis BCG, M. paratuberculosis, and keyhole limpet hemocyanin.

Pages

230

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