IL-1 Receptor Type II

Dinarello Ch.A.

The extracellular domains of type II IL-1R are structurally related to those of the type I IL-1R; however, the type II IL-1R is a decoy receptor in that the primary ligand, IL-1♀, preferentially binds to this receptor rather than the signaling receptor. As such, in the presence of increasing expression of the type II receptor on the cell surface, less IL-1 signaling takes place. This is because the type II IL-1R lacks a cytoplasmic domain capable of cell signal transduction. The type II IL-1R also exists in a shed form as asoluble receptor. The soluble receptor has a high affinity to bind IL-1♀ over that of IL-1♂ or IL-1Ra. The soluble IL-1R type II is ideally suited for clinical use because it has a high affinity for IL-1♀ and a low affinity for IL-1Ra.