Superhero Immune Cells—Why Does the Body Fight a Transplanted Organ?

Organ transplantation is a surgery in which doctors replace a person’s sick or damaged organ with a healthy organ from another person. The new organ can come from a living person who wants to help, or from someone whose brain died and thus does not need their organs anymore. The main problem with organ transplants is rejection, which happens when the immune system treats the new organ like a foreign invader such as an infection and tries to remove it. To prevent rejection, patients who received an organ transplant need to take many pills for the rest of their lives. These pills, called immunosuppressants, weaken the immune system and prevent it from attacking the new organ. Unfortunately, immunosuppressants also make the patients more susceptible to infections or cancer. Scientists are looking for ways to “re-program” the immune system, to decrease the likelihood of rejection.