The bovine model for elucidating the role of γδ T cells in controlling infectious diseases of importance to cattle and humans

There are several instances of co-investigation and related discoveries and achievements in bovine and human immunology; perhaps most interesting is the development of the BCG vaccine, the tuberculin skin test and the more recent interferon-gamma test that were developed first in cattle to prevent and diagnosis bovine tuberculosis and then applied to humans. There are also a number of immune-physiological traits that ruminant share with humans including the development of their immune systems in utero which increases the utility of cattle as a model for human immunology. These are reviewed here with a particular focus on the use of cattle to unravel gamma delta T cell biology. Based on the sheer number of gamma delta T cells in this gamma delta T cell high species, it is reasonable to expect gamma delta T cells to play an important role in protective immune responses. For that reason alone cattle may provide good models for elucidating at least some of the roles gamma delta T cells play in protective immunity in all species. This includes fundamental research on gamma delta T cells as well as the responses of ruminant gamma delta T cells to a variety of infectious disease situations including to protozoan and bacterial pathogens. The role that pattern recognition receptors (PRR) play in the activation of gamma delta T cells may be unique relative to alpha beta T cells. Here we focus on that of the gamma delta T cell specific family of molecules known as WC1 or T19 in ruminants, which are part of the CD163 scavenger receptor cysteine rich (SRCR) family that includes SCART1 and SCART2 expressed on murine gamma delta T cells. We review the evidence for WC1 being a PRR as well as an activating co-receptor and the role that gamma delta T cells bearing these receptors play in immunity to leptospirosis and tuberculosis. This includes the generation of memory responses to vaccines, thereby continuing the tradition of co-discovery between cattle and humans. (C) 2014 Elsevier Ltd. All rights reserved.