A bone marrow transplant, also known as a hematopoietic stem cell transplant, replaces damaged or diseased bone marrow with healthy stem cells. This treatment is often employed for individuals with certain cancers of the blood or bone marrow, such as leukemia and lymphoma, as well as other conditions like aplastic anemia or immune deficiency disorders. Its primary goal is to restore the body’s ability to produce healthy blood cells by infusing healthy blood-forming stem cells after the patient’s unhealthy bone marrow has been treated.
The Direct Answer
A bone marrow transplant can change a recipient’s blood type if the donor’s blood type differs from the recipient’s. Following a successful transplant, the new blood-forming cells from the donor begin to produce blood with the donor’s characteristics. This means the recipient’s blood type will gradually convert to the donor’s. For instance, a recipient with type A blood might become type O if their donor has type O blood.
How Blood Type Changes
The change in blood type after a bone marrow transplant stems from the biology of blood cell production. Bone marrow contains hematopoietic stem cells, which generate all types of blood cells, including red blood cells, white blood cells, and platelets.
When a patient undergoes a bone marrow transplant, their existing, unhealthy bone marrow is often cleared through chemotherapy or radiation. The healthy stem cells from the donor are then infused into the recipient’s bloodstream, where they travel to the bone marrow and begin to engraft, meaning they settle and grow. As these new donor stem cells multiply, they produce a supply of blood cells.
The ABO blood type is determined by specific antigens, or markers, on the surface of red blood cells. These antigens are genetically determined. Since the donor’s stem cells carry their unique genetic information, the red blood cells produced by the new marrow will express the donor’s blood type. This transition is gradual, occurring as the recipient’s original red blood cells are replaced by newly formed donor cells over weeks or months.
Addressing Blood Type Mismatches
When a donor and recipient have different ABO blood types, careful management ensures a safe transplant. This situation, known as ABO incompatibility, does not prevent a transplant, but it requires specific clinical strategies.
One common approach involves removing red blood cells from the donor’s bone marrow product before infusion. This is important when the donor’s red blood cells carry antigens that the recipient’s body would recognize as foreign, potentially leading to a severe reaction.
Another technique is plasma exchange on the recipient. Plasma exchange removes the recipient’s antibodies that react against the donor’s blood type. For instance, if a type O recipient is receiving marrow from a type A donor, the recipient’s anti-A antibodies could attack the donor’s red blood cells. Performing plasma exchange significantly reduces these antibodies, minimizing the risk of adverse reactions during and after the transplant. These procedures are important for navigating blood type differences and facilitating engraftment.
Life with a New Blood Type
After a successful bone marrow transplant and blood type change, the recipient’s medical care adapts to their new blood identity. For all future blood transfusions, the recipient will receive blood matching their new, donor-derived blood type. Healthcare providers update medical records to reflect this change, important for ensuring proper blood product selection.
The Rh factor, which determines if a blood type is positive or negative, generally remains the recipient’s original Rh type. This is because its genes are found outside the hematopoietic stem cells, unlike ABO antigens. While the ABO blood type changes, the Rh factor typically does not, though rare Rh incompatibility can lead to specific immune responses.
The change in blood type highlights the impact of donor stem cells on the recipient’s hematopoietic system. This ensures the long-term health and compatibility of the recipient’s blood with their new marrow.