The present application provides human antibodies and antigen binding fragments thereof that specifically bind to the human interleukin-21 receptor (IL-21 R). The antibodies can act as antagonists of IL-21 R activity, thereby modulating immune responses in general, and those mediated by IL-21 R in particular. The disclosed compositions and methods may be used for example, in diagnosing, treating or preventing inflammatory disorders, autoimmune diseases, allergies, transplant rejection, cancer, and other immune system disorders.
