RIG-I is an intracellular checkpoint that limits CD8 T-cell antitumour immunity.

Retinoic acid-inducible gene I (RIG-I) is a pattern recognition receptor involved in innate immunity, but its role in adaptive immunity, specifically in the context of CD8 T-cell antitumour immunity, remains unclear. Here, we demonstrate that RIG-I is upregulated in tumour-infiltrating CD8 T cells, where it functions as an intracellular checkpoint to negatively regulate CD8 T-cell function and limit antitumour immunity. Mechanistically, the upregulation of RIG-I in CD8 T cells is induced by activated T cells, and directly inhibits the AKT/glycolysis signalling pathway.