Butyrophilin subfamily 3 member A1 and Butyrophilin subfamily 2 member A1 complex (BTN3A1/BTN2A1)

The Phosphoantigen-loaded BTN3A1/BTN2A1 complex is a specialized molecular structure on the surface of cells that serves as the primary recognition signal for Vγ9Vδ2 T cells, a potent subset of gamma-delta T cells. BTN3A1 (CD277) functions as an intracellular sensor for phosphoantigens (pAgs), such as isopentenyl pyrophosphate (IPP), which are often elevated in tumor cells due to dysregulated mevalonate metabolism (Rigau et al., Science, 2020). Upon pAg binding to the intracellular B30.2 domain of BTN3A1, the protein undergoes a conformational change that requires the co-association of BTN2A1 to be effectively presented to the Vγ9Vδ2 T-cell receptor (Karunakaran et al., Immunity, 2020). This complex acts as a molecular bridge, facilitating the direct killing of tumor cells by γδ T cells and the release of pro-inflammatory cytokines like IFN-γ and TNF-α (Vantourout et al., Science Translational Medicine, 2013). In therapeutic contexts, this complex is targeted by agonistic antibodies, such as ICT01, which bypass the need for high endogenous pAg levels by stabilizing the active state of the complex (ImCheck Therapeutics, 2024). This approach aims to harness the innate-like properties of γδ T cells for broad-spectrum anti-tumor activity across various solid and hematological malignancies.

Other names

CD277BTN3A1-BTN2A1 complexPhosphoantigen-presenting complexBTN3A1/BTN2A1/pAg complex

Agonistic monoclonal antibodies bind to the extracellular domain of BTN3A1 to induce or stabilize a conformational change that mimics phosphoantigen loading, thereby facilitating the engagement of Vγ9Vδ2 T cell receptors and subsequent tumor cell lysis (de Gassart et al., Science Immunology, 2021).