BTN3A1 (Butyrophilin Subfamily 3 Member A1) plays a role in T-cell activation and in the adaptive immune response. It regulates the proliferation of activated T-cells and the release of cytokines and IFNG by activated T-cells. It also mediates the response of T-cells toward infected and transformed cells that are characterized by high levels of phosphorylated metabolites, such as isopentenyl pyrophosphate.