Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2006
Publication Date: 6/15/2006
Citation: Waters, W.R., Palmer, M.V., Thacker, T.C., Minion, F.C., Davis, W.C. 2006. Antigen-specific proliferation and activation of peripheral blood mononuclear cells from Mycobacterium bovis-infected reindeer. Veterinary Immunology and Immunopathology. 111(2006): 263-277. Interpretive Summary: Reindeer are routinely tested for tuberculosis by tuberculin skin testing as outlined in the USDA uniform methods and rules for the eradication of bovine tuberculosis in the United States. However, skin testing has an apparent lack of specificity as numerous reindeer are classified as reactors using skin test procedures yet the bacterium is not isolated from tissues when the animal is killed. Improved techniques are needed for tuberculosis surveillance of reindeer. To develop improved tests, it is beneficial to first understand the immune response to infection. In this study, responses by white blood cells isolated from infected reindeer were characterized. Findings from this study will be useful for developing new tests for the tuberculosis surveillance program for reindeer and other deer species.
Technical Abstract: The purpose was to evaluate antigen-specific and polyclonal proliferative and activation-associated responses by blood mononuclear cells from Mycobacterium bovis-infected reindeer. Peripheral blood mononuclear cells (PBMC) from M. bovis-infected (n = 10) and non-infected reindeer (n = 4) were stimulated with a recombinant early secretory antigenic target-6 and culture filtrate protein-10 fusion protein (ESAT6:CFP10, antigens specific to tuberculous mycobacteria), M. bovis purified protein derivative, pokeweed mitogen, or medium alone and evaluated for proliferation and activation marker expression by flow cytometry. gd TCR**+ and CD8**+ cells, but not CD4**+ cells, from M. bovis-infected reindeer proliferated in response to specific antigen stimulation. Expression (i.e., mean fluorescence intensity) of CD44 was increased and CD62L decreased on proliferative as compared to non-proliferative PBMC in antigen- and mitogen-stimulated cultures. In response to stimulation with rESAT6:CFP10, MHC II fluorescence intensity was increased on CD4**+,'gd TCR**+, CD172a**+, and IgM**+ cells as compared to non-stimulated cells from infected, but not non-infected, reindeer. rESAT6:CFP10 stimulation also induced expansion of a CD172a**+,MHC II**+ population within PBMC cultures from M. bovis-infected reindeer. Despite a moderate challenge dose and an extended duration of infection, experimental infection of reindeer was generally limited to lymph nodes draining the inoculation site. Therefore, in vitro findings presented in this study may be predictive of host resistance to tuberculous mycobacteria.