4. HLA (Human Leukocyte Antigens) Matching


Human leukocyte antigens (HLA) are proteins or markers that are located on

the surface of most cells and tissues in the body. Every person has specific

HLA markers that recognize which cells belong in the body.


When two people share the same HLA, they are referred to as a “match”.

Their tissues are immunologically compatible with each other.


HLA typing is used to match patients and donors for bone marrow, peripheral

blood and cord blood stem cell transplants.

Some stem cell transplants require an EXACT HLA MATCH

Bone marrow and peripheral blood stem cell transplants REQUIRE AN EXACT MATCH between the sick patient

and the donor:

If there is not a suitable match, the patient’s immune cells will attack their body’s cells after the transplant. This is called Graft Vs Host Disease (GVHD) and is one of the most serious and potentially deadly complications in transplant medicine.

“About 70% of patients who need a (bone marrow)

transplant do not have a suitable donor in their family.”

National Marrow Donor Association, USA

www.marrow.org accessed 07.02.11

Cord blood stem cell transplants DO NOT REQUIRE AN EXACT HLA MATCH:

Cord blood stem cells are more primitive and adaptable cells than bone marrow and peripheral blood stem cells. Cord blood stem cells do not require an exact HLA antigen match between the patient and the donor. Therefore, it is easier and faster to find a suitable donor. In addition, the incidence of complications such as GVHD is reduced and, if present, is usually less severe.

Because cord blood only requires a 4/6 (or in some instances 3/6) match, there is a 50% chance of a match between siblings and even a possible match with extended family members.