Although we try to match antigens as much as possible for kidney and pancreas recipients, we do transplant organs into recipients who have no antigens in common, and these patients do very well. Some of them have never had a rejection episode. In other cases, we have seen patients who have had an exact six-antigen match have rejection occur because there are other antigens that have not yet been identified that may play a role in rejections.
Unfortunately, there is no way of predicting who will experience rejection and it can occur at anytime. Crossmatching Crossmatching is a test done just before transplant. A crossmatch determines if your body already has antibodies formed against the donor's antigens. Toggle navigation Transplant Center. Toggle navigation Transplantation. Your immune system uses these markers to recognize which cells belong in your body and which do not.
How donors and patients are matched. You have many HLA markers. Extended family members are not likely to be close HLA matches. Research has found that a donor must match a minimum of 6 HLA markers. Some people may also need to have a component of HLA typing performed after transplant, to see if their body is making antibodies to the transplanted tissue. This might be one sign that organ rejection is taking place, and the transplant may not be a success. There are many different health conditions that may need to be treated through a transplant.
For example, various types of blood cancers and genetic blood disorders are treated through stem cell transplantation taken either from the bone marrow or from the peripheral blood. For example, it is a curative treatment for sickle cell disease. A solid organ transplant might be necessary for any essential organ that has become severely damaged. This might happen through trauma, infection, autoimmune disease, genetic illness, toxins, or many other disease processes. Often, a transplant provides the last hope of a treatment cure.
The HLA system refers to a group of related genes that play an important role in the immune system. Together, the proteins made from these genes form something called the major histocompatibility complex MHC.
These proteins are attached to almost all of the cells of your body excluding red blood cells. There are many possible variations in these attached proteins that your other cells can detect.
They are part of how your body recognizes which cells belong in your body and which do not. As an analogy, you can visualize the HLA proteins as different colored strings floating off the cell. In our example, our own cells are programmed to recognize a certain pattern of string colors that belong to us. For example, you could imagine that your HLA types include a black string, a bright blue string, a light violet string, and a yellow string.
If an immune cell notices a cell with an orange HLA protein string, it would send off alarm bells. That warns the cell that it might be seeing something potentially dangerous, like a virus. This might trigger the immune system to attack the cell. The HLA system plays an important role in immune defense. However, it also helps determine who can give and receive tissue successfully.
If the immune system targets the donated tissue as foreign, i. Because there are a number of different HLA genes, as well as different variations of these genes, there are very many different possible color combinations that together make up your specific HLA type. Antibodies are made by part of the immune system. If a person already has an antibody against an HLA protein i.
This may cause the transplant to fail. Similarly, HLA typing also often includes something called lymphocyte crossmatching. Lymphocytes are a type of immune cell. There are only eight basic blood types, and many people can safely receive more than one type of blood depending on their type.
To receive only blood from a person, you do not need to be an HLA match, because HLA is not present on red blood cells. However, to receive a solid organ transplant, the recipient must have a compatible blood type with the donor, as well as the best HLA match possible. For stem cell donations, one needs a very strong HLA match, but blood type is not as important as it is for solid organ transplants.
Because the HLA genes are located close together on your DNA, they are usually inherited as a group—you inherit a whole set of colors not just one individual color at a time. In our analogy, the HLA genes contain information about the "color of the strings" your cells will have. Biological parents always share half of their HLA proteins with their children. In our analogy, a child would share half of the colors on his cells with each of his parents.
Siblings who share both parents are most likely to be an identical HLA match. Such siblings have a 1 in 4 chance of being a perfect HLA match with perfectly matching colored strings. There is also about a one in two chance that siblings will share half of the HLA markers and be a half-match.
For a solid organ transplant like a kidney that can be given by living donors , it may be worth getting HLA typing for other members of the family as well: uncles, aunts, and more to help find a good match.
Because stem cell donations require a higher percentage of HLA matches, it is less likely that a suitable match will be found this way. This is part of the reason it may be harder for some people to find a good HLA match than others. For example, bone marrow registries currently contain fewer potential donors of African American descent.
This may make it less likely that these individuals can find a good HLA match from a non-relative. HLA typing is a genetic test.
0コメント