Porcine γδ T cells:: Possible roles on the innate and adaptive immune responses following virus infection

gamma delta T cells recognise different types of antigen in alternative ways to a p T cells, and thus appear to play a complementary role in the immune response. However, unlike up T cells, the role or function of gamma delta T cells is still unclear. As pigs possess a high proportion of circulating gamma delta T cells, they are suitable large animal model to Study gamma delta T cell functions. This as yet has not been fully exploited, leaving porcine gamma delta T cell biology and its role in immunity in its infancy. Foot-and-mouth disease (FMD) high potency emergency vaccines are able to induce early protection from challenge and it has been suggested that, in part, there is some involvement of innate immune responses. The antigen component of the vaccine is able to stimulate purified naive pig gamma delta T cells and induce the mRNA of various cytokines and chemokines. This observation suggests that gamma delta T cells probably contribute to the early phase of the immune responses to FMD vaccination, and perhaps infection. A subset of these circulating gamma delta T cells display a phenotype similar to professional antigen presenting cells and are able to take up and present soluble antigen to CD4(+) T cells in a direct cell-cell interaction via MHC class II. This direct interaction between gamma delta T cells and CD4(+) T cells is likely to have a significant influence on the out come of the adaptive immune response. (c) 2006 Elsevier B.V. All rights reserved.