Is there a relationship between bone marrow typing and blood type?

Generally, bone marrow typing is not directly related to blood type, as they belong to different genetic systems. The detailed explanation is as follows:

Blood type is determined by antigens on the surface of red blood cells, such as the ABO and Rh blood group systems. In contrast, the core of bone marrow typing lies in matching human leukocyte antigens (HLA). HLA molecules are located on human chromosome 6 and play a crucial role in the immune system's ability to distinguish between "self" and "non-self" substances. They are key factors influencing the risk of rejection after transplantation.

In clinical practice, bone marrow transplantation places more emphasis on the compatibility of HLA typing, while matching blood types is not an absolute requirement. Even if the donor and recipient have different blood types, the recipient's blood type can gradually convert to that of the donor after transplantation. During this period, blood transfusion support and other measures can help avoid the risk of hemolysis.

However, it should be noted that ABO blood type incompatibility may increase the likelihood of hemolytic reactions early after transplantation. Clinicians may adjust the pre-transplant conditioning regimen to reduce this risk. In contrast, HLA mismatch significantly increases the chances of graft rejection and transplant failure.