T cells expressing γδ T cell antigen receptors (TCR) are a non-conventional T-cell population. 1-3 In humans and non-human primates (NHPs), there is a unique γδ T cell subpopulation expressing TCR heterodimer bearing Vγ2 and Vδ2 segments, termed Vγ2Vδ2 (also Vγ9Vδ2) T cells. 4 Studies carried out over several decades have addressed fundamental aspects of Vγ2Vδ2 T cells during tuberculosis (TB) and other infections. 3,5-8 Vγ2Vδ2 T cells are the sole γδ T cell subpopulation capable of recognizing phosphoantigens such as microbial (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP) and the isoprenoid metabolites isopentenyl pyrophosphate (IPP). 9-11 HMBPP is produced only by the non-mevalonate pathway present in some selected microbes, such as Mycobacterium tuberculosis (Mtb), M bovis BCG and Listeria, whereas IPP can be produced by the mevalonate pathway of cholesterol synthesis in eukaryotic cells. 9,10 Phosphoantigen HMBPP-specific Vγ2Vδ2 T cells, exist only in humans and NHPs. They account for 65%-90% of total peripheral blood γδ T cells in healthy adults, play crucial role in both innate and adaptive immunity, 12-15 and mount major expansion and effector responses during infections with Mtb and other pathogens. 3,5,7,8,16,17 Recent seminal studies in NHP models demonstrate that primary TB infection or phosphoantigen with IL-2 (such as HMBPP + IL-2) administration could specifically induce expansion of Vγ2Vδ2 T cells in vivo; following expansion, they are fast-acting, multi-functional, and protective against infection with high doses of Mtb. 3,5-8 Notably, rapid recall-like expansion of Vγ2Vδ2 T cells correlates with detectable immunity against fatal tuberculosis (TB) after Mtb challenge of bacillus Calmette-Guérin (BCG)-vaccinated macaques. 3 Proof-of-concept (POC) and definitive studies are needed to address the question as to whether human Vγ2Vδ2 T cells play important roles in protective immunity against Mtb and other infections. This question has been long-standing since human γδ T cells were discovered over 30 years ago. This existing gap is largely attributed to the