Butyrophilin3A proteins and V gamma 9V delta 2 T cell activation

Despite playing critical roles in the immune response and having significant potential in immunotherapy, gamma delta T cells have garnered little of the limelight. One major reason for this paradox is that their antigen recognition mechanisms are largely unknown, limiting our understanding of their biology and our potential to modulate their activity. One of the best-studied gamma delta subsets is the human V gamma 9V delta 2T cell population, which predominates in peripheral blood and can combat both microbial infections and cancers. Although it has been known for decades that V gamma 9V delta 2T cells respond to the presence of small pyrophosphate-based metabolites, collectively named phosphoantigens (pAgs), derived from microbial sources or malignant cells, the molecular basis for this response has been unclear. A major breakthrough in this area came with the identification of the Butyrophilin 3A (BTN3A) proteins, members of the Butyrophilin/Butyrophilin-like protein family, as mediators between pAgs and V gamma 9V delta 2T cells. In this article, we review the most recent studies regarding pAg activation of human V gamma 9V delta 2T cells, mainly focusing on the role of BTN3A as the pAg sensing molecule, as well as its potential impact on downstream events of the activation process. (C) 2018 Elsevier Ltd. All rights reserved.