αβ T cells, accounting for 65%-70% of the T cell population, recognize “non-self” or tumor neoantigens presented by target cells’ MHC molecules through their surface receptor TCR specificity. In contrast, γδ T cells, constituting 0.5%-5% of all T lymphocytes, have TCRs composed of γ and δ chains and are mainly found in epithelial and mucosal tissues such as the skin and intestines. γδ T cells can recognize target antigens independent of MHC restriction and effectively kill tumors and pathogens through the activation by non-peptide phosphoantigens (PAgs).PAgs are metabolites of tumor cells or microbial pathogens. Tumor cells with aberrant cholesterol metabolism accumulate large amounts of endogenous DMAPP and IPP, while pathogens like Gram-negative bacteria and malaria parasites produce a different type of isoprenoid pyrophosphate, HMBPP.DAMPP, IPP, and HMBPP can activate γδ T cells. Exogenous HMBPP, differing chemically from endogenous DMAPP and IPP produced by tumors, has an additional hydroxyl group. HMBPP’s ability to activate γδ T cells is nearly a thousand times higher than that of DMAPP and IPP, with an EC50 in the picomolar range. HMBPP binds to the cytoplasmic domain of BTN3A1, forming two hydrogen bonds with BTN3A1’s cytoplasmic amino acids H351 and Y352. This hydrogen bond interaction induces a conformational change in BTN3A1’s extracellular domain, enhancing its binding capacity with the γδ T cell receptor and promoting γδ T cell activation. The main subset of γδ T cells in peripheral blood is Vγ9Vδ2 T cells. Research has developed antibodies against the butyrophilin subfamily 3 member A1 (BTN3A1), which can specifically activate γ9δ2 T cells without relying on PAgs.The Vγ9Vδ2 (G115) Reporter Jurkat (TCRαβ KO) Cell Line, a luciferase reporter cell line, is constructed based on TCR α/β chain knockout Jurkat cells. Activation of downstream signaling pathways occurs when BTN3A antibody binds to BTN3A expressed in Jurkat cells or Vγ9Vδ2 TCR antibody binds to Vγ9Vδ2, leading to luciferase expression. Luciferase readings indicate the activation effect of the signaling pathway and can be used to evaluate the in vitro effects of Vγ9Vδ2-related drugs.
