HLA typing before transplantation: understanding compatibility testing

An HLA report can contain many letters and numbers, creating a natural wish for a simple “suitable” or “unsuitable” answer. For a transplant team, the result is part of a wider assessment. Ask which stage of matching has been completed, what the findings establish and which checks remain.

Understand why HLA is tested

HLA refers to protein markers present on most cells in the body. Testing helps assess compatibility between a patient and a potential blood stem cell donor. It informs allogeneic transplant planning but does not define the entire risk or guarantee an outcome. The matching principle is explained in the NCI transplant guide.

Do not substitute a blood-group record or general information about a relative for the requested HLA report. Send the specific document the centre needs. If you are unsure which investigation has already been performed, show the complete laboratory name and report to the team instead of ordering a test with a similar title yourself.

Check requirements before sampling

The NMDP information on HLA typing explains that testing may use blood or a cheek swab. The organisation conducting the matching should provide instructions about the investigation and sample required. Ask which laboratory format is needed, what the request must include and where the official result will be sent.

When assessment takes place across cities or countries, agree how samples will be identified. Names, birth dates and identifiers should be consistent across patient and potential-donor records. Keep the original report, collection date and laboratory contact. For a transplant consultation, send the complete file including comments rather than a cropped photograph of one matching result.

Ask what has actually been compared

Ask the transplant specialist which results are being compared, whether the available testing is sufficiently detailed and whether confirmation is required. If correspondence uses an abbreviation or fraction, request an explanation in the context of your proposed care. Do not compare numerical labels from separate laboratories before establishing that they describe the same scope of testing.

Family relationship does not replace laboratory matching. Arrange relatives’ investigations according to the team’s request, confirming who should be tested first and the documents each person needs. This avoids unnecessary or unsuitable tests and confusion between an initial result and confirmed information used in decision-making.

Identify the next milestone

Ask whether the current status is receipt of patient results, comparison underway, identification of a potential option, or completion of further checks. These are different milestones. NMDP notes that donor selection also considers factors beyond HLA, so a close match is not independent clearance for donation or transplantation.

Before organising treatment travel, establish what must be completed before arrival and what will happen at the centre. Record the contact responsible for updates and the next review date. This guide supports document preparation and questions; interpretation of compatibility and donor-strategy decisions require the specialist clinical team.