Vγ9Vδ2 T cells recognize butyrophilin 2A1 and 3A1 heteromers

著者: Thomas S. Fulford, Caroline Soliman, Rebecca G. Castle, Marc Rigau, Zheng Ruan, Olan Dolezal, Rebecca Seneviratna, Hamish G. Brown, Eric Hanssen, Andrew Hammet, Shihan Li, Samuel J. Redmond, Amy W. Chung, Michael A. Gorman, Michael W. Parker, Onisha Patel, Thomas S. Peat, Janet Newman, Andreas Behren, Nicholas A. Gherardin, Dale I. Godfrey, Adam P. Uldrich - Nature Immunology 2024 被引用: 44

Butyrophilin (BTN) molecules are emerging as key regulators of T cell immunity; however, how they trigger cell-mediated responses is poorly understood. Here, the crystal structure of a gamma-delta T cell antigen receptor (γδTCR) in complex with BTN2A1 revealed that BTN2A1 engages the side of the γδTCR, leaving the apical TCR surface bioavailable. We reveal that a second γδTCR ligand co-engages γδTCR via binding to this accessible apical surface in a BTN3A1-dependent manner. BTN2A1 and BTN3A1 also directly interact with each other in cis, and structural analysis revealed formation of W-shaped heteromeric multimers. This BTN2A1–BTN3A1 interaction involved the same epitopes that BTN2A1 and BTN3A1 each use to mediate the γδTCR interaction; indeed, locking BTN2A1 and BTN3A1 together abrogated their interaction with γδTCR, supporting a model wherein the two γδTCR ligand-binding sites depend on accessibility to cryptic BTN epitopes. Our findings reveal a new paradigm in immune activation, whereby γδTCRs sense dual epitopes on BTN complexes. In this study, Uldrich and colleagues describe the crystal structure of the Vγ9Vδ2 T cell antigen receptor (TCR) interacting with BTN2A1 and demonstrate the existence of a second ligand that co-binds to a distinct epitope on Vγ9Vδ2 TCR. Using these data, the authors suggest a model of Vγ9Vδ2 TCR activation in which BTN2A1 and BTN3A1 are tethered to each other at the steady state, and must disengage to allow TCR binding.