The receptor for Interleukin 35 (IL-35) is provided. The Interleukin 35 Receptor (IL-35R) comprises a heterodimeric complex of the Interluekin12Rβ2 receptor and the gp130 receptor. Various compositions comprising the IL-35R complex, along with polynucleotides encoding the same and kits and methods for the detection of the same the same are provided. Methods of modulating the activity of IL-35R or modulating effector T cell functions are also provided. Such methods employ various IL-35R antagonists and agonists that modulate the activity of the IL-35R complex and, in some embodiments, modulate effector T cell function. Further provided are methods for screening for IL-35R binding agents and for IL-35R modulating agents. Various methods of treatment are further provided.
