HLA Test: Purpose, Procedure, Interpretation
HLA typing is a type of genetic test that is used to determine specific differences in a person’s immune system. The procedure is crucial for determining who can safely donate bone marrow, cord blood, or an organ to a transplant recipient. Although HLA stands for human leukocyte antigen, it is typically always abbreviated to HLA. HLA matching is another term for HLA typing.
What is HLA Typing Test?
HLA typing is a next-generation sequencing-based test that aids in finding the best match for allogeneic bone marrow and organ transplant donor selection. HLA of the donor, which the recipient recognizes as intruders, causes rejection in the bone marrow and organ transplantation. The result of transplantation is heavily influenced by the careful selection of a compatible donor and recipient.
HLA-B27 is a particular protein (also known as a human leukocyte antigen or HLA) present on the surface of cells. The gene that codes for the HLA-B27 protein is sometimes referred to as HLA-B27. The presence or absence of HLA-B27 protein on the surface of a person’s white blood cells is determined by the HLA-B27 test.
Why do you need the HLA Test?
- During a bone marrow transplant, the recipient’s immune system may mistake the donor’s bone marrow for a foreign body and reject it.
- The greater the mismatch, the more likely you are to be rejected.
- The generation of proteins that can cause rejection is determined by the HLA gene sequence.
- As a result, it’s critical to match the immunological signatures of potential donors and recipients.
What is the purpose of HLA Test?
The most common purpose for HLA typing is to assess who is most suited to perform tissue transplants safely (solid organ or hematopoietic stem cell transplantation). Anyone who would desire to give tissue, as well as potential tissue recipients, must have the type. This could include family members of someone who needs a transplant.
People can also volunteer to have their HLA type entered into a bone marrow registry in the hopes of receiving stem cell transplants. HLA typing can also be done on persons who are terminally ill or have recently died and will be serving as organ donors.
Let us discuss in detail about Donor Registries: A confidential electronic database where individuals can register and store their desire to be organ and tissue donors. The majority of registries accept applications through motor vehicle offices, and many also offer online registry portals. Because registry information is available to authorized procurement professionals on a 24/7 basis, it is the safest and quickest approach to identify if a deceased person wants to be a donor or looking out for a donor with a complete match.
There is a number of authorized registries around the world that works for social welfare, names include:
- DKMS: German Registry
- DATRI: Indian Registry
- A USA-based registry: Be The Match, operated by the National Marrow Donor Program® (NMDP), has managed the most diverse marrow registry in the world.
The optimal donors have HLA patterns that closely match the recipient’s HLA patterns. This increases the probability that the transplant will successfully treat your disease and reduces the chance of post-transplant complications, such as organ rejection.
After the transplant, some people may need to have a component of HLA typing done to assess if their bodies are producing antibodies to the transplanted tissue. This could indicate that organ rejection is occurring and that the transplant will not be successful.
The HLA-B27 test may be performed in conjunction with other blood, urine, or imaging tests to confirm the diagnosis of autoimmune disease in persons who have certain symptoms such as joint pain, stiffness, or swelling of your spine, neck, or chest.
What is the procedure of the HLA Typing Test?
A needle is inserted into a vein in your arm to get a blood sample. A buccal swab (a swab of cells collected from the inside of your cheek) is sometimes used for testing. Neither approach necessitates any particular preparation.
Although, HLA blood test cost in India starts from USD 40.
When do you need to get the Test?
The treating doctor may choose to use this test to verify the compatibility of the donor tissue before performing a bone marrow transplant or an organ transplant.
The general public should not be tested on a regular basis. Only those with symptoms of specific blood disorders are usually checked. The following list of disorders required HLA typing tests are mentioned below:
- For various organ transplantation like Heart, Kidney, and Liver.
- To match donors for patients suffering from Sickle Cell Anemia and Bone Marrow Transplant.
- To diagnose other blood disorders: Lymphoma, Leukemia Myeloma, and Hemophilia.
- HLA-B27 Test is linked to a variety of autoimmune and immune-mediated conditions, including Ankylosing Spondylitis, Reactive Arthritis, Juvenile Rheumatoid Arthritis
The amount of HLA markers that any two people share is referred to as an HLA match. HLA matching is often done using eight or ten HLA markers. The better the match, the more markers two people share. It is stated that two people are a good match if they have the same HLA markers.
The most likely area for two people to find an HLA match is among siblings who share the same mother and father. An HLA-identical match occurs when two siblings inherit the exact same HLA markers from both parents.
It’s also possible that two unrelated people are an excellent HLA match. Although unlikely, it is possible that you share some HLA markers with someone you don’t know.
For understanding in detail, we have shared genuine HLA test reports of patients of fully matched and Mismatch results below:
HLA Report for Full Match Results
HLA Report For Mismatch Results
For HLA B-27 Test interpretation:
A negative test means you don’t have HLA-B27 in your blood.
However, a negative test result does not rule out the possibility of an autoimmune disease. Your doctor will evaluate all test results as well as your symptoms before reaching a final diagnosis. HLA-B27 is not always present on white blood cells in persons with autoimmune diseases.
If the test results are positive, HLA-B27 is present in your blood. Although a positive result is concerning, the presence of the antigen does not always imply the development of an autoimmune disease. Your symptoms, as well as the results of all blood tests and diagnostic exams, must be used to make an autoimmune disease diagnosis.
What is the protocol to understand the role of HLA Match/Mismatch results?
After the HLA typing test, as a minimum, the recipient and donor should have HLA-A, -B, -C typed at intermediate or higher resolution by DNA-based methods, and HLA-DRB1 typed at high resolution by DNA-based methods. At HLA-A, -B, -C, and -DRB1, the recipient and related donor should be a 7/8 match for example.
To comprehend the facts, the patient must analyze his or her HLA testing result in such a way that if the patient’s HLA locus score is 5/10, this may not be a good match for transferring or donating blood cells, platelets, or organs. The donor-to-patient matching ratio should be 10/10, and this will be deemed a good perfect match.
Important note: Only genuine siblings with genetically identical parents can match the 10/10 locus in HLA. Also, there’s a 50% chance that a child’s human leukocyte antigen ratio will match that of his or her parent.
For understanding in detail, we have shared genuine HLA test reports of patients of fully matched results below: