There is provided the use of an antagonist of IL-TIF activity in the manufacture of a medicament for treating an inflammatory or immune disease in a mammal, wherein said antagonist is an antibody that specifically binds to a heterodimeric receptor complex having a first receptor subunit consisting of a zcytoR11 polypeptide as shown in SEQ ID NO:3 and a second receptor subunit consisting of a CRF2-4 receptor polypeptide as shown in SEQ ID NO:33.