Generation and characterization of rat anti-mouse ST2L monoclonal antibodies.

ST2L is a transmembrane receptor that belongs to the IL-1 receptor family. The receptor is expressed on various cell types including Th2 cells, mast cells, basophils, growth-activated fibroblasts, and vascular endothelial cells. ST2L activation by its ligand IL-33 has been implicated in Th2-mediated immunity, inflammation, and allergic responses in vivo. Inhibition of ST2L activity can attenuate Th2-dominated immune responses such as lung eosinophilia, airway hyper-responsiveness, and arthritis in animal models. Here we report the generation and in vitro characterization of a panel of rat anti-mouse ST2L monoclonal antibodies. We demonstrate that the antibodies specifically bind to recombinant receptor protein and that a subset of the binders inhibits mouse ST2L activity in multiple in vitro assays. Four of the identified anti-mouse ST2L antibodies were shown to prevent IL-33 from binding to ST2L, down-regulate IL-33-induced NF-κB signaling, and neutralize the ability of IL-33 to stimulate mouse Th2 cell proliferation. The characterized monoclonal antibodies are important tools that will be used to study mouse ST2L receptor functionality in vivo.