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What donor is the best match for a patient is ultimately determined by the patient's attending physician. The key factor in this decision is your tissue or HLA typing (stem cell information). It has to match that of the patient. We will contact you if you are a (potential) match with a patient. You do not have to do anything yourself. If you do not hear from us, that means you are not a match.
When someone registers as a stem cell donor, their HLA typing (tissue typing) is determined using cheek mucosa samples collected with cotton swabs. The HLA typing predominantly determines if a donor is a good match for a patient. The patient's body uses the donor's stem cells to build its new immune system. If the patient's body rejects the donor's stem cells as foreign or if the donor's stem cells view the patient's body as foreign, serious or even lethal complications may occur.
It is therefore important that the tissue typing of a donor's stem cells matches that of a patient as closely as possible. Finding a donor with the right tissue typing is called ‘matching'.
The key factors for making a match are:
- HLA (Human Leukocyte Antigen) is the most important factor. It must be the same or match as closely as possible. Ideally, we are looking for a 10-out-of-10 match.
- Age is another very important factor. A young donor is preferable because the quality of their stem cells is higher and the transplantation of the cells into the patient's body is more likely to succeed. In addition, the risk of complications for the donor increases as they get older.
- Gender is another factor we take into account. Male donors are generally preferable, as their bodies have more stem cells. Some female donors may have been pregnant at some point. This makes their stem cells less suitable for donation, as it increases the risk of rejection symptoms for the patient.
- CMV, also known as the cytomegalovirus, is a generally harmless virus and many people have undergone a CMV infection without even realizing it. However, this virus can cause problems for a patient receiving a stem cell transplantation. That is why we want to know if a donor is CMV positive or negative (i.e. if they have been infected with the CMV virus or not). If a CMV-positive patient receives stem cells from a CMV-negative donor, this can cause serious problems for the patient. To a lesser extent, the same principle applies if a CMV-negative patient receives stem cells from a CMV-positive donor.
- Urgency for the patient, i.e. how urgently a patient needs the stem cell transplantation, is another important factor in the choices we make. We may e.g. choose a donor from a nearby country or opt for an alternative such as umbilical blood, because this is faster.
- Lastly, we consider such factors as the donor's weight, high-risk behavior, travel history in recent months and their availability.