Porcine gd T cells: Possible roles on the innate and adaptive immune responses following virus infection H.-H. Takamatsu a, * , M.S. Denyer a , C. Stirling a , S. Cox b , N. Aggarwal b , P. Dash a , T.E. Wileman a,c , P.V. Barnett b a Immunology Division, Institute for Animal Health, Pirbright Laboratory, Pirbright, Woking, Surrey GU24 0NF, UK b FMD vaccine Research Group, Institute for Animal Health, Pirbright Laboratory, Pirbright, Woking, Surrey GU24 0NF, UK c University of East Anglia, School of Medicine, Norwich NR4 7TJ, UK Abstract gd T cells recognise different types of antigen in alternative ways to ab T cells, and thus appear to play a complementary role in the immune response. However, unlike ab T cells, the role or function of gd T cells is still unclear. As pigs possess a high proportion of circulating gd T cells, they are suitable large animal model to study gd T cell functions. This as yet has not been fully exploited, leaving porcine gd 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 naı ¨ve pig gd T cells and induce the mRNA of various cytokines and chemokines. This observation suggests that gd T cells probably contribute to the early phase of the immune responses to FMD vaccination, and perhaps infection. A subset of these circulating gd 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 gd T cells and CD4 + T cells is likely to have a significant influence on the out come of the adaptive immune response. # 2006 Elsevier B.V. All rights reserved. Keywords: Porcine gd T cells; Cytokine; Foot-and-mouth disease virus 1. Introduction T cells expressing gd TCR (gd T cells) are only a minor subset of T cells in humans and mice, however, these gd T cells are a prominent lymphocyte subset in certain farm animal species such as chickens, ruminants and pigs (Born et al., 1999). Although a defined role for the gd T cells is still unclear, the popular view of the role of gd T cells is as a first line of defence, with the other innate immune response. If this view is correct, and given that pigs have a high proportion of NK cells (Fig. 1), the pig may be well suited to study the innate immune system in details. In ruminants, the advantage of possessing a high proportion of gd T cells was utilized in characterizing www.elsevier.com/locate/vetimm Veterinary Immunology and Immunopathology 112 (2006) 49–61 * Corresponding author. Tel.: +44 1483 232 441x1089; fax: +44 1483 232 448. E-mail address: haru.takamatsu@bbsrc.ac.uk (H.-H. Takamatsu). 0165-2427/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.vetimm.2006.03.011