Special features of γδ T cells in ruminants

Ruminant gamma delta T cells were discovered in the mid-1980's shortly after a novel T cell receptor (TCR) gene from murine cells was described in 1984 and the murine TCR. gene locus in 1985. It was possible to identify gamma delta T cell populations early in ruminants because they represent a large proportion of the peripheral blood mononuclear cells (PBMC). This null cell population, gamma delta T cells, was designated as such by its non-reactivity with monoclonal antibodies (mAb) against ovine and bovine CD4, CD8 and surface immunoglobulin (Ig). gamma delta T cells are non-conventional T cells known as innate-like cells capable of using both TCR as well as other types of receptor systems including pattern recognition receptors (PRR) and natural killer receptors (NKR). Bovine gamma delta T cells have been shown to respond to stimulation through toll-like receptors, NOD, and NKG2D as well as to cytokines alone, protein and non-protein antigens through their TCR, and to pathogen-infected host cells. The two main populations of gamma delta T cells are distinguished by the presence or absence of the hybrid co-receptor/PRR known as WC1 or T19. These two populations not only differ by their proportional representation in various tissues and organs but also by their migration into inflamed tissues. The WC1(+) cells are found in the blood, skin and spleen while the WC1 gamma delta T cells predominate in the gut, mammary gland and uterus. In ruminants, gamma delta T cells may produce IFN gamma, IL-17, IL-10 and TGF beta, have cytotoxic activity and memory responses. The expression of particular WC1 family members controls the response to particular pathogens and correlates with differences in cytokine responses. The comparison of the WC1 gene families in cattle, sheep and goats is discussed relative to other multigenic arrays that differentiate gamma delta T cells by function in humans and mice.

Automated summary

Ruminant gamma delta T cells were discovered in the mid-1980's and play an important role in the immune response of ruminants. These non-conventional T cells are capable of using multiple receptor systems and produce different types of cytokines in response to stimulation through specific receptor systems, contributing to host defense against pathogens.