Finding a donor

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Patients receiving blood stem cell transplants are matched with a volunteer donor through a test called HLA tissue typing. The immune system uses HLA proteins found in the surface of cells to identify which cells belong to your own body and which do not.

Transplant physicians start looking for a matching donor in the patient’s family, but will extend the search when no matching donor is available in the family. Alternatives for a matching family donor may be:

family members who are not a complete HLA match;
unrelated adult volunteers who are a complete HLA match;
umbilical cord blood units that are a complete HLA match; or
unrelated volunteers or umbilical cord blood units that are not a complete HLA match.

Searching

If a patient requires a blood stem cell transplant, the transplant physician will contact and consult the national registry and/or the Search & Match Service to find as close a match as possible. The Search & Match Service provides a global database that lists millions of potential donors and cord blood units worldwide. Transplant physicians will know if there’s a potential match for their patient within a few seconds. In many countries, national stem cell donor registries and specialist search coordinators assist transplant physicians in the search.

Matching

Because HLA markers are inherited, half from your mother and half from your father, each brother and sister who shares the same parents as you has a 25% chance (1 in 4) of being a close HLA match. A close match reduces the risk of the patient’s immune system attacking the foreign cells, or of the donor’s cells attacking the patient’s body. However, many people do not have a good match within their family.

After the search

Once a potential match has been found, the donor will need to give their consent and be confirmed as healthy to donate. A second round of ‘verification’ HLA typing is then carried out, before the transplant physician puts in a formal request for a stem cell donation. The patient will undergo medical tests and examinations before the transplantation; the transplant physician will make sure the patient is otherwise healthy and does not have any medical issues that may cause complications post treatment.

More patients information

Transplantation: the basics Who needs transplantation? Finding a donor Risks of transplantation