The PathHunter IL-31RA/OSMRβ Bioassay Kit provides a robust, highly sensitive and easy-to-use cell-based functional assay to study receptor-ligand interactions on the cell surface. This kit has been designed to rapidly measure potency of the biologic drug, or detect the presence of neutralizing antibodies against the biologic. The bioassay kit contains all materials needed to run the assay, including cryopreserved cells, detection reagents, cell plating reagent, control agonist, and assay plates. The ready-to-use cryopreserved cells have been manufactured for single-use to ensure assay reproducibility, and faster implementation from characterization to lot release. This assay has been optimized for a 96-well format.