Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Review Article
Publication Acceptance Date: April 1, 2014
Publication Date: June 1, 2014
Citation: McGill, J.L., Sacco, R.E., Baldwin, C.L., Telfer, J.C., Palmer, M.V., Waters, W.R. 2014. The role of gamma delta T cells in immunity to Mycobacterium bovis infection in cattle. Veterinary Immunology and Immunopathology. 159(3-4)133-143. doi.org/10.1016/j.vetimm.2014.02.010. Technical Abstract: Accumulating evidence suggests that gamma delta (gd) T cells play a critical role in the early response to M. bovis and may be key in bridging innate and adaptive immunity following infection. In vitro, gd T cells proliferate and produce robust amounts of IFNy in response to complex, protein and non-protein mycobacterial antigens including M. bovis purified protein derivative (PPD), heat shock proteins and cell wall components such as mycolylarabinogalactan peptidoglycan (mAGP). Vaccination with BCG, as well as infection with virulent M. bovis, induces an increase in the frequency and activation of WC1+ gd T cells circulating in the blood. gd T cells are rapidly recruited to the lungs and draining lymph nodes following BCG vaccination, and accumulate in developing lesions early following M. bovis infection. In SCID-bo mice, depletion of gd T cells prior to M. bovis infection results in impaired granuloma formation, suggesting a role for gd T cells in immune cell recruitment and lesion development. In vivo depletion of WC1+ gd T cells from calves prior to M. bovis infection results in significantly reduced levels of M. bovis specific IgG2 and IFNy, and increased IL-4 production compared to non-depleted control animals, suggesting that gd T cells may also play a role in shaping the character of the adaptive M. bovis specific immune response. While it is clear that 'd T cells are responding during M. bovis infection, much remains to be understood about their function in vivo and their ability to shape the innate and adaptive immune response. This review focuses on recent advances in our understanding of gd T cell biology with a particular emphasis on the immune response of gd T cells in cattle during M. bovis infection.