Gamma-delta T cell subsets are differentially associated with granuloma development and organization in a bovine model of mycobacterial disease

P>The characteristic lesion in bovine tuberculosis is well-organized respiratory granulomas. This is typically associated with a strong T-helper 1 biased cell-mediated immune response and eventual containment of the infection. In bovine paratuberculosis, the classic lesion is unorganized granulomatous intestinal inflammation. Clinical paratuberculosis is associated with a T-helper 2 biased humoral immune response and eventual death because of inability of the host to contain the infection. Recent reports have suggested that gamma-delta (gamma delta) T cells play a significant role in granuloma development and/or maintenance during initial stages of infection and may influence the subsequent adaptive immune response. The objective of this study was to use an in vivo bovine model to evaluate gamma delta T cells during the early host immune response to mycobacterial infection. We used immunofluorescent staining, hyperspectral microscopy, and computerized assisted morphometry to evaluate staining and distribution of gamma delta T cells during development of organized and unorganized granulomas. Our data suggest that bovine gamma delta T cell subsets are differentially recruited to early infection sites, and may be instrumental during the initial antimycobacterial host immune response as well as for granuloma organization.