There is provided an isolated multimeric or heterodimeric cytokine receptor comprising: a first polypeptide, wherein the first polypeptide comprises an amino acid sequence having at least 90 percent sequence identity with residues 20-732 of SEQ ID NO:111 or an amino acid sequence having at least 90 percent sequence identity with residues 20-649 of SEQ ID NO:109; and a second polypeptide comprising residues 28-429 of SEQ IDNO:7; wherein the multimeric or heterodimeric cytokine receptor binds a ligand comprising residues 27-164 of SEQ ID NO:2.