The invention relates to an antibody or antigen-binding fragment thereof which binds to the CC chemokine receptor GPR-9-6 and blocks the binding of a ligand (e.g., TECK) to the receptor. The invention also relates to a method of identifying agents (molecules, compounds) which can bind to GPR-9-6 and inhibit the binding of a ligand (e.g., TECK) and/or modulate a function of GPR-9-6. The invention further relates to a method of modulating a function of GPR-9-6, and to the use of the antibodies, antigen-binding fragments and agents identified by the method of the invention in research, therapeutic, prophylactic and diagnostic methods.