Are organ and tissue type matched the same way?
Tissue types are determined by different proteins than blood, which are expressed on different cells. The importance of matching tissue type in organ transplantations depends on the organ. It's important to match organs for kidney transplantations, for example, but liver and heart transplantations can be performed just by matching blood type.
Bone marrow transplant recipients also require a matching donor, is that right?
Yes. Matches are absolutely critical in bone marrow transplantation. Sometimes people will even bank their own marrow before certain procedures, or acquire matches from close relatives.
What actually happens when a person receives blood or organs that are not a match?
The rejection can occur in a number of ways. Essentially your body makes antibodies and immune "killer cells," and they're going to come out and they're going to attack. Normally the body is attacking infectious agents. In this case, the body attacks the donated graft. And if it's a rejection for, let's say, a liver transplant, your body realizes that the liver is foreign. And the antibodies and killer cells will attack the organ and destroy it.
There are two types of particularly bad rejection reactions. One is called the "hyperacute rejection." In this case, the antibodies to the other blood type are already formed, and are essentially lying in wait. They begin to attack the organ right away, and this is the worst type of reaction. The organ can turn black within an hour. It's a terrible thing to see.
