The role of HLA in umbilical cord blood transplantation

Transplantation with umbilical cord blood for haematological malignancy and other diseases has increased over the last two decades. The parameters that affect clinical outcome have been intensely studied in this relatively new clinical setting. Although originally thought to not be critical for transplant success, human leucocyte antigen (HLA) matching of the patient and cord blood donor is now considered one of the most important indicators of outcome. Because clinical studies of cord-blood transplantation are often not large enough to detect subtle differences, the HLA matching algorithm in cord blood transplantation (CBT) is not clearly defined. This article will focus on HLA matching in CBT in relation to engraftment, graft versus host disease, relapse and survival. Outstanding questions in the field, such as the contribution of HLA-C, -DQ, as well as the appropriate level of HLA matching and cord unit selection will be discussed.