Submitted to: Keystone Symposia
Publication Type: Proceedings
Publication Acceptance Date: 1/24/2001
Publication Date: N/A
Technical Abstract: Despite highly successful eradication efforts in several countries, Mycobacterium bovis infection of cattle remains a significant health concern worldwide. Immune mechanisms of resistance to and/or clearance of M. bovis infection of cattle, however, are unclear. Additionally, white-tailed deer have recently emerged as reservoirs for M. bovis infection of cattle within the United States. The presence of a wildlife reservoir for M. bovis is significantly hindering eradication efforts. In the present study, we utilized a flow cytometric-based proliferation assay to determine the relative contribution of individual lymphocyte subsets from M. bovis infected deer and cattle in the proliferative response to in vitro stimulation with purified protein derivative (PPD). In vitro stimulation with PPD induced a prominent response by both CD4+ T cells and gd TCR+ cells from cattle and CD4+ T cells from deer. Addition of monoclonal antibodies specific for MHC II antigens abrogated the proliferative response of infected deer to PPD; further demonstrating the significance of the CD4+ T cell response to PPD. Intradermal administration of PPD to infected cattle for detection of a delayed type hypersensitive response boosted the in vitro CD4+ T cell but not the gd TCR+ cell response to PPD. While it is clear that subsets other than CD4+ T cells from infected deer and cattle respond to PPD, CD4+ T cells are likely the most significant responders.