Costimulatory pathways in transplantation

► Costimulatory pathways have a critical role in the regulation of alloreactivity. ► A complex network of positive and negative pathways regulates T cell responses. ► Blocking costimulation improves allograft survival in rodents and non-human primates. ► The costimulation blocker belatacept is being developed as immunosuppressive drug in renal transplantation.