What is HLA?
The full name of HLA is “human leukocyte antigen” and is primarily associated with the initiation and regulation of the body’s immune response.
HLA is a highly polymorphic alloantigen, which means that each individual has a unique HLA, and due to ethnogenetic differences, the Chinese have a different HLA type than the white and black populations.
In a population, the probability of finding two individuals with identical HLA is approximately 1 in 100,000, whereas in siblings, the probability of an HLA match is 25%. The HLA match between parents and children is 50%, often referred to as “HLA semimatch”.
When do I need to be HLA-matched?
Just like a difference in blood type.
Just as two people with different blood types cannot transfuse each other, organ transplantation and hematopoietic stem cell transplantation can result in very serious immune rejection if two people have incompatible leukocyte antigens, i.e., HLA incompatibility, leading to rejection of the implant or even endangering the patient’s life.
Thus, we must perform an HLA match to find an HLA-compatible donor suitable for stem cell donation before performing a HSCT.
What happens if the match is not successful?
What happens if the match is not successful?
HSCT donor selection:
- Siblings: 25% chance of HLA compatibility, 50% chance of HLA semimatch, and another 25% chance of HLA incompatibility.
- Searching for HLA-matched unrelated donors: Unrelated donors with HLA-matched patients are searched for in the Chinese Bone Marrow Bank (or in cord blood banks for children) by searching the HLA information of enrolled volunteers. The current capacity of the Chinese Bone Marrow Bank is 2.5 million, and approximately 10% of patients can find a donor with an HLA match in the Chinese Bone Marrow Bank.
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If a patient does not find a fully compatible HLA donor, or if the disease is progressing rapidly and there is an urgent need for HSCT, they can choose a parent or child as a donor. Parent/child HLA is hemizygous, and given the current advances in transplantation technology, the success rate of hemizygous transplantation and the effectiveness of treatment are now well established.