Cellular responses and Mycobacterium bovis BCG growth inhibition by bovine lymphocytes.
Cellular responses of a group of cattle immunized subcutaneously with a low dose of Mycobacterium bovis bacille Calmette-Guerin vaccine (BCG) were measured in vitro and compared with nonimmunized control animals. PBMC taken from immunized animals proliferated and produced IFN-gamma in the presence of M. bovis BCG culture filtrate proteins. The addition of PBMC from immunized animals to M. bovis BCG-infected autologous macrophages also resulted in secretion of IFN-gamma. In contrast, the responses of PBMC from control animals were comparatively low over the period of study. In experiments to study the interaction of non-adherent lymphocytes with infected macrophages, M. bovis BCG growth was inhibited in cultures containing autologous PBMC from immunized and non-immunized control animals. The degree of inhibition was related to lymphocyte concentration but did not correlate with IFN-gamma production. Treatment of macrophages with recombinant IFN-gamma prior to, or postinfection did not alter the intracellular growth kinetics of mycobacteria. It appears, therefore, that although M. bovis BCG immunization of cattle stimulates the generation of a T cell-mediated immune response to M. bovis BCG, the cattle may already possess a high level of innate resistance to M. bovis BCG that requires the presence of lymphocytes.
Carpenter
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E
Department of Veterinary Pathology and Public Health, Massey University, Palmerston North, New Zealand.
Fray
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L
Gormley
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E
D000818:Animals; D001500:BCG Vaccine / Q000276:immunology* / Q000378:metabolism; D002417:Cattle; D002455:Cell Division; D002478:Cells, Cultured; D018920:Coculture Techniques; D005260:Female; D007371:Interferon-gamma / Q000096:biosynthesis / Q000276:immunology; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology*; D008264:Macrophages / Q000166:cytology / Q000276:immunology* / Q000382:microbiology; D009163:Mycobacterium bovis / Q000254:growth & development / Q000276:immunology* / Q000378:metabolism
D001500:BCG Vaccine; D007371:Interferon-gamma