Recent advances in the understanding of T cell activation have led to new therapeutic
approaches in the treatment of immunological disorders. One attractive target of intervention
has been the blockade of T cell costimulatory pathways, which result in more selective
effects on only those T cells that have encountered specific antigen. In fact, in some
instances, costimulatory pathway antagonists can induce antigen-specific tolerance that
prevents the progression of autoimmune diseases and organ graft rejection. In this review …