biostudies-literatureWillcox CRGuy’s and St Thomas’ Charity PrizeFrancis Crick InstituteKing’s Bioscience InstituteCancer Research UKThe Francis Crick InstituteMedical Research CouncilNational Institute for Health Research (NIHR)Wellcome Trust813-825.e4https://www.ebi.ac.uk/biostudies/studies/S-EPMC6868513biostudies-literatureUnknown51(5)Butyrophilin (BTN) and butyrophilin-like (BTNL/Btnl) heteromers are major regulators of human and mouse γδ T cell subsets, but considerable contention surrounds whether they represent direct γδ T cell receptor (TCR) ligands. We demonstrate that the BTNL3 IgV domain binds directly and specifically to a human Vγ4⁺ TCR, "LES" with an affinity (∼15-25 μM) comparable to many αβ TCR-peptide major histocompatibility complex interactions. Mutations in germline-encoded Vγ4 CDR2 and HV4 loops, but not in somatically recombined CDR3 loops, drastically diminished binding and T cell responsiveness to BTNL3-BTNL8-expressing cells. Conversely, CDR3γ and CDR3δ loops mediated LES TCR binding to endothelial protein C receptor, a clonally restricted autoantigen, with minimal CDR1, CDR2, or HV4 conImmunityButyrophilin-like 3 Directly Binds a Human Vγ4<sup>+</sup> T Cell Receptor Using a Modality Distinct from Clonally-Restricted Antigen.PMC6868513FC00109310093NIHR-INF-1086099266/Z/12/Z208400/Z/17/Z106292/Z/14/Z10015Hayday ACWillcox BESalim MMelandri DJeeves MZanardo LZlatareva IGeorge RKjaer SMohammed FWillcox CRVantourout PfalseButyrophilin-like 3 Directly Binds a Human Vγ4<sup>+</sup> T Cell Receptor Using a Modality Distinct from Clonally-Restricted Antigen.Butyrophilin (BTN) and butyrophilin-like (BTNL/Btnl) heteromers are major regulators of human and mouse γδ T cell subsets, but considerable contention surrounds whether they represent direct γδ T cell receptor (TCR) ligands. We demonstrate that the BTNL3 IgV domain binds directly and specifically to a human Vγ4⁺ TCR, "LES" with an affinity (∼15-25 μM) comparable to many αβ TCR-peptide major histocompatibility complex interactions. Mutations in germline-encoded Vγ4 CDR2 and HV4 loops, but not in somatically recombined CDR3 loops, drastically diminished binding and T cell responsiveness to BTNL3-BTNL8-expressing cells. Conversely, CDR3γ and CDR3δ loops mediated LES TCR binding to endothelial protein C receptor, a clonally restricted autoantigen, with minimal CDR1, CDR2, or HV4 con2019-01-01T00:00:00Z2019 Nov2026-05-03T18:38:47.8Z2021-02-19T19:44:02ZS-EPMC68685133162805310.1016/j.immuni.2019.09.006