Role of V gamma 9v delta 2 T lymphocytes in infectious diseases

The T cell receptor V gamma 9V delta 2 T cells bridge innate and adaptive antimicrobial immunity in primates. These V gamma 9V delta 2 T cells respond to phosphoantigens (pAgs) present in microbial or eukaryotic cells in a butyrophilin 3A1 (BTN3) and butyrophilin 2A1 (BTN2A1) dependent manner. In humans, the rapid expansion of circulating V gamma 9V delta 2 T lymphocytes during several infections as well as their localization at the site of active disease demonstrates their important role in the immune response to infection. However, V gamma 9V delta 2 T cell deficiencies have been observed in some infectious diseases such as active tuberculosis and chronic viral infections. In this review, we are providing an overview of the mechanisms of V gamma 9V delta 2 T cell-mediated antimicrobial immunity. These cells kill infected cells mainly by releasing lytic mediators and pro-inflammatory cytokines and inducing target cell apoptosis. In addition, the release of chemokines and cytokines allows the recruitment and activation of immune cells, promoting the initiation of the adaptive immune response. Finaly, we also describe potential new therapeutic tools of V gamma 9V delta 2 T cell-based immunotherapy that could be applied to emerging infections.