Butyrophilin subfamily 3 member A1–Butyrophilin subfamily 2 member A1 complex (BTN3A1–BTN2A1 complex) (BTN3A1–BTN2A1)

The BTN3A1–BTN2A1 complex is a critical molecular sensor located on the surface of various cells, including tumor cells, that mediates the activation of Vγ9Vδ2 T cells, the predominant subset of gamma-delta T cells in human peripheral blood (Rigau et al., Science, 2020). This complex functions by detecting intracellular phosphoantigens (pAg), such as isopentenyl pyrophosphate (IPP), which accumulate in metabolically stressed or transformed cells due to dysregulation of the mevalonate pathway (Karunakaran et al., Immunity, 2020). Upon pAg binding to the intracellular B30.2 domain of BTN3A1, a conformational change is induced that facilitates the association of BTN3A1 with BTN2A1, which then presents a specific molecular pattern recognized by the Vγ9Vδ2 T-cell receptor (TCR) (UniProt O00481, Q7RTZ9). In oncology, this complex is targeted by agonistic monoclonal antibodies, such as ICT01, which are designed to stabilize the active conformation and bypass the requirement for high endogenous pAg levels. This therapeutic approach aims to selectively recruit and activate gamma-delta T cells to eliminate cancer cells through direct cytotoxicity and cytokine production. The complex represents a novel checkpoint in innate-like immunity, offering a distinct mechanism from traditional alpha-beta T-cell-targeted therapies.

Other names

CD277Butyrophilin 3A1Butyrophilin 2A1BTN3A1BTN2A1pAg-sensing complexVγ9Vδ2 TCR ligand

Agonistic monoclonal antibodies bind to the extracellular domains of the BTN3A1/BTN2A1 complex to induce or stabilize a conformational change that mimics phosphoantigen-induced activation, thereby triggering Vγ9Vδ2 T-cell-mediated cytotoxicity against target cells (Rigau et al., 2020; Karunakaran et al., 2020).