Butyrophilin-like 3 and 8 tetramers clamp Vγ4Vδ1 T cell receptors for antigen-independent activation.

BTNL3-BTNL8 forms an antigen-independent tetramer that clamps Vγ4Vδ1 TCRs, revealing a unique activation mechanism in human γδ T cells.

• Why it matters: Understanding how Vγ4⁺ T cells are activated independently of antigens is crucial for insights into intestinal immune homeostasis and tissue repair, addressing a gap in γδ T cell activation mechanisms.
• What they did: The study determined the structure of the BTNL3-BTNL8-Vγ4Vδ1 TCR complex, showing that two BTNL3-BTNL8 heterodimers form a tetramer that engages the TCR, with specific loops involved in binding.
• The result: This structural insight clarifies how BTNL3-BTNL8 mediates TCR engagement and activation, advancing knowledge of γδ TCR signaling initiation and potential immune regulation strategies.