HLA Matching


HLA matches are required for life saving stem cell transplants. If you don't have your HLA typed, consider doing so today!

What Makes A Match?

Matching is determined by your HLA type. When people join Pareto, they provide a sample of their HLA by swabbing their cheek. This cheek swab is tested for a minimum of 6 HLA markers.

A patient’s doctor will usually choose several donors who appear to match the patient at a basic level. The doctor will ask that these donors have additional tests. These detailed tests will show which donor’s HLA most closely matches the patient’s HLA markers. These tests are usually blood tests or additional cheek swabs.

Best Matching

The best marrow transplant outcomes happen when a patient’s human leukocyte antigen (HLA) and the HLA of a registry member closely match. This is much more complex than matching blood types. HLA is a protein marker found on most cells in your body. Your immune system uses HLA markers to know which cells belong in your body and which do not. There are many HLA markers that make a person’s tissue type unique; however, matching certain markers is what is critical to a successful transplant.

Rules for HLA Matching

There are rules for the minimum number of HLA matches needed between a donor and patient. Research shows that patients have better outcomes with a closely matched donor. Sometimes doctors want to match 8 HLA markers. Other times, doctors want to match 10 markers. These are a few matching rules:

  • Pareto requires that patients and donors from our platform match at least 6 of 8 HLA markers.
  • For a haploidentical (half-matched) transplant, donors match exactly half, or 5 of 10, HLA markers. The donor is usually the patient’s parent or child.

Different transplant centers may have different matching rules. Ask your transplant team what the minimum HLA match is at your center.

Doctors Use HLA to Choose the Best Donor

A close match between a donor’s and a patient’s HLA markers is essential for a successful transplant outcome. Doctors want to find the best possible donor for each patient. Usually, it’s a patient whose HLA are very closely matched to yours.

A close match is important because it:

  • Improves the chances for a successful transplant.
  • Helps the patient's donor cells engraft (grow and make new blood cells in their body).
  • Reduces the risk of complications like graft-versus-host disease (GVHD). GVHD happens when the immune cells from the donated cells (the graft) attack the recipient’s cells (the host).

There are times when a closely matched donor isn’t the best option. For some patients, a donor who matches exactly half of their HLA is best. This is called a haplo-identical (or half-matched) transplant.

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