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Matching a donor and recipient for a blood stem cell transplant

The matching process for blood stem cell transplants
July 29, 2022

Before you are contacted and asked to donate, a patient’s medical team are looking for donors with Human Leukocyte Antigens (HLA) markers that closely match a patient’s HLA markers. The patient’s medical team want to find the most suitable match.

Why are HLA markers so important when it comes to matching?

HLA are protein markers that can be found on the majority of cells in the human body. The immune system reads these markers to determine whether they belong to the body or are foreign. If the immune system identifies something in the body as foreign, it will begin to attack them. The more HLA markers that match, the higher chance of a successful transplant and a reduction in complications for the patient.

How do you find out what my HLA markers are?

When you signed up to join in recent years, you would have provided a cheek swab or a blood sample. The lab processed your sample to identify your HLA markers, which have been added to your information in our database. Thanks to modern advances in technology, we can now identify more markers than before, making the matching process easier. However, for those who signed up to the registry a while ago, chances are we haven’t got enough information about your HLA markers. If you are chosen as a potential match, you will likely undergo additional testing to identify all of your HLA markers relevant for transplant.

When a patient’s medical team is looking for a match, they will want to match at least eight HLA markers for a donor to be considered a suitable match for a patient.

Anything else I should know about HLA markers?

For the curious among you, the HLA markers on your cells are determined by your parents. 50% of your markers come from your mum, and 50% come from your dad. If you have siblings, you have a 25% chance of being a match to them, meaning when a patient requires a blood stem cell transplant, seven times out of ten, they are looking for an unrelated donor. Ethnicity also plays a vital role in HLA matching, all thanks to our genes!

When a patient’s medical team is searching for potential donors, they review HLA markers to see those who are closely matched. On average, eight potential donors are selected to undergo further testing to determine the most suitable donor. Usually, further testing requires a blood test and health questionnaire. Of these eight potential donors, only one or two will proceed toward donation. It is common for donors to get to this point and feel disappointed they cannot proceed. It is also ok to feel this way – you care and want to help. The good news is that undergoing additional testing increases your chances of being selected to donate to another patient.

The bottom line – HLA matching kick starts the process of contacting you, the donor, to let you know you are a potential match for a patient in need of a transplant!


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