The long-term kidney allograft survival rate is still far from optimum
. Conventional immunosuppressive drugs used to prevent allograft rejec
tion are associated with significant side effects. Moreover, withdrawa
l of these agents is often associated with graft loss due to rejection
. No treatment is available for chronic rejection. Graft tolerance is
difficult to achieve in humans, and therefore a continued goal in orga
n transplantation is to develop immunosuppressive regimens that are as
sociated with fewer side effects and decreased rates of rejection, and
that promote graft tolerance. The advent of newer pharmacologic agent
s and bioreagents is expected to improve patient and graft survival ra
tes.