Inducible T Cell Costimulatory Ligand (ICOSL)

Inducible T cell costimulatory ligand (ICOSL) is a type I transmembrane protein that serves as the exclusive ligand for the inducible T cell costimulator (ICOS), a receptor expressed on activated T cells. ICOSL is a member of the B7 family of immune regulatory molecules and plays an essential role in modulating adaptive immune responses by providing critical costimulatory signals necessary for full T cell activation and function.

Other names

B7RP-1CD275ICOS LigandICOSLG

The interaction between ICOS on activated T cells and ICOSL on APCs provides a crucial "second signal" required for optimal activation of naive T cells beyond antigen recognition through the TCR/CD3 complex. Blockade of this pathway can ameliorate disease progression by reducing inflammation-driven tissue damage mediated by aberrant Th1/Th2 responses or pathogenic autoantibody production from B-cells.