How Organ Transplants Work

Living with a New Organ

As with most other surgeries, recovery from a transplant operation involves additional medication and hospital visits to make sure the incisions heal correctly. But while other surgery patients typically can move on from the experience, most transplant recipients must continue medical treatment for the rest of their lives. This is because of the immune system's reaction to the new organ.

Your immune system comprises all the elements in your body that keep bacteria, microbes, viruses, toxins and parasites from destroying your organs and tissues. In other words, the immune system works to destroy any harmful foreign matter that ends up in your body. When the system is working correctly, it can distinguish most foreign cells from cells produced by the body. (See How Your Immune System Works to find out how it does this.)

A transplanted organ is made entirely of foreign cells, of course, which means the body will attack it if left to its own devices. To minimize the immune response, transplant teams make sure donors and recipients have matching blood and tissue types. But even with a good match, the body will see the new cells as foreign matter and reject the organ (destroy it cell by cell). Only tissue from an identical twin will be fully accepted.

There are three types of rejection that might occur following a transplant:

  • Hyperacute rejection occurs as soon as the donated organ is in the body. This only happens if there are already antibodies in the recipient's bloodstream that react to the new organ, which would occur if the blood types of the donor and recipient were incompatible for some reason. This almost never happens, since transplant teams always test for any incompatibility ahead of time. If it were to happen, the recipient would most likely die on the operating table.
  • Acute rejection occurs at least a few days after the transplant, after the body has had time to recognize the foreign material. This is the normal immune response to foreign matter.
  • Chronic rejection is a very gradual rejection, lasting months or years. It can be so subtle that the patient doesn't notice any ill effects for some time.