HLA stands for human leukocyte antigen, a group of proteins present on the surface of all cells on the human body.
Each individual carries a particular combination of proteins in the HLA set. There are different types of HLA -- A, B, C, DP, DQ and DR. We all have 2 HLA molecules of each type, inherited from either parent. Therefore, the final HLA combination serves as a molecular identifier for an individual. The immune system of the body uses the HLA combination to identify each cell in the body as their own.
When ‘foreign cells’ in the form of organ or marrow transplants are placed inside an individual’s body, a mismatched HLA is recognized and the body may reject these cells or organs. The HLA sets of the donor and the recipient must be as close a match as possible for a successful transplant. Matching of HLA -A, B, C and DR are recommended for a succesful bone marrow or stem cell transplant. This minimizes the risk of transplant rejection and its associated complications.
Identical twins have the same HLA set. Parents, siblings and even unrelated individuals may also have matching HLA. Lab tests can identify the HLA type of a person and test if another individual’s HLA matches it or not. HLA matching is an essential step before an allogeneic transplant.
Source:
The HLA Factsbook. Authors: Marsh, Parham and Barber. Published by Elsevier, 1999.
