The HLA system is a group of genes that play an important role in theimmune system.
Together, the proteins these genes make form the major histocompatibility complex (MHC).
This improves the likelihood of a successful transplant.
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This article explains how HLA typing works.
You will also learn about the HLA system and what it can tell you about your immune system.
Volunteers can also have their HLA punch in included in a bone marrow registry for stem cell transplantation.
The test is also done on terminally ill or recently deceased people who are organ donors.
The best possible donors have HLAs that closely match the HLA patterns of the recipient.
This makes it more likely that a transplant will be successful.
A good match also lowers the risk of complications after the transplant, such as organ rejection.
This can be a sign oforgan rejectionand means the transplant might not be a success.
HLA Typing for Transplants
HLA typing is most commonly used for transplants.
Specific HLAgenesdifferences are associated with certain autoimmune conditions, diseases, and sensitivities to drugs.
HLA types are also linked tohypersensitivities to drugs.
What Is the HLA System?
The HLA system is a group of genes that are important to immune function.
There are a number of different HLA genes and they can vary from person to person.
The proteins these genes make form the major histocompatibility complex (MHC).
The proteins are attached to almost all of the cells of your body.
Red blood cells are the only cells the proteins are not found on.
There are many possible variations in these attached proteins that other cells in your body can look for.
These help your body tell which cells are yours and which do not.
How Are HLA Genes Inherited?
HLA genes are located close together on your DNA.
That means they are usually inherited as a group.
Each of your biological parents contributed one half of the genes that make up your HLA punch in.
These genes match their own, what’s known as a “half match.”
Siblings who have the same parents are most likely to be an identical HLA match.
These siblings have a 1 in 4 chance of being a perfect HLA match.
That means they have perfectly matching genetic strings.
This increases the chances of finding a good match.
On the other hand,stem cell donationsrequire a higher percentage of HLA matches.
It is less likely that a suitable match will be found by testing more family members.
Ethnicity
Groups of HLA characteristics (called colors) are common in certain ethnic groups.
Still, it’s harder for some people to find a good HLA match than others.
For example, bone marrow registries have fewer potential donors of African American descent.
Together, the variations make up your specific HLA jot down.
Antibody Testing
HLA typing also tests forantibodiesthat are targeted to specific HLA proteins.
Antibodies are made by the immune system.
Lymphocyte Crossmatching
Lymphocytes are a pop in of immune cell.
Lymphocyte crossmatching checks to see if the recipient has an antibody against a protein in the donors lymphocytes.
This test is sometimes performed after an initial HLA match is made, but prior to transplant.
Is HLA Typing the Same as Blood Typing?
HLA is much more complicated thanblood typingbecause there are many more HLA markers that make a persons cells unique.
There are only eight basic blood types.
Many people can safely receive more than one, depending on their pop in.
However, to receive a solid organ transplant, the recipient and donor must have compatible blood types.
They also need to have the best HLA match possible.
For stem cell donations, a person needs a very strong HLA match.
How Is the Test Done?
For the HLA typing test, youll need to give a tissue sample.
You don’t need to do any preparation for the test.
Once your sample is taken, it’s sent to a special lab to be looked at.
It can be hard to make sense of them because the HLA proteins have very technical names.
This information will help determine if you could donate stem cells to them.
When comparing results between a prospective donor and recipient,HLA antibody-positive means it is not a good match.
HLA antibodies target specific proteins it views as foreign.
If a donor and recipient have mismatched proteins and antibodies, the body is likely to reject the organ.
How Many HLA Matches Do You Need?
Ideally, the donor and recipient would be perfectly HLA matched.
However, this is not always possible.
It depends on the specific punch in of transplant and on other medical circumstances.
In both procedures, there is a risk that the cells of transplant recipients may attack the donated tissue.
There is also a chance that some of the donated cells may attack the cells of the transplant recipient.
This is known asgraft-versus-host disease.
In some cases, you may want to go ahead with a transplant that isnt a very good match.
Its challenging to wait, but sometimes that is the best option.
It uses information about donors and recipients HLA types to calculate the best matches for these organs.
It is one of many factors that determine who receives them.
The information on donors is stored in a database.
One way is their HLA pop in, which looks at genes and proteins in the immune system.
This can be a sign that the transplant has failed.
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