Immunosuppressive therapy is appropriate for the prevention or reversa
l of allograft rejection, and for the treatment of autoimmune disorder
s and allergic disease. Recent advances in our understanding of the ce
llular and molecular mechanisms that regulate immune responses have pa
ralleled elucidation of the modes of action of a variety of therapeuti
c immunosuppressive agents, both 'old' and new. These developments hav
e identified potential targets for more refined and specific intervent
ion strategies that are now being tested in the clinic.