MERTK Acts as a Costimulatory Receptor on Human CD8 T Cells.

The TAM family of receptor tyrosine kinases (TYRO3, AXL, and MERTK) is known to be expressed on antigen-presenting cells and function as oncogenic drivers and as inhibitors of inflammatory responses. Both human and mouse CD8 T cells are thought to be negative for TAM receptor expression. In this study, we show that T-cell receptor (TCR)-activated human primary CD8 T cells expressed MERTK and the ligand PROS1 from day 2 postactivation.