Which blood type is the universal recipient?

Which blood type is the universal recipient?

• A. Type AB blood
• B. Type O blood
• C. Type A blood
• D. Type B blood

Answer: (A)

The key idea is compatibility of surface antigens and antibodies in blood. A person is a universal recipient in the ABO system when their blood plasma lacks both anti-A and anti-B antibodies, so they won’t attack donor red cells of any ABO type. Type AB blood has both A and B antigens on the red blood cells and, importantly, no anti-A or anti-B antibodies in the plasma. This means they can receive red blood cells from any ABO type—A, B, AB, or O—without mounting an immune attack. In contrast, someone with type O blood has no A or B antigens on their cells but their plasma contains both anti-A and anti-B antibodies, so they can only receive from type O. Type A blood has anti-B antibodies, so it can receive from A or O, but not from B or AB. Type B blood has anti-A antibodies, so it can receive from B or O, but not from A or AB. Note the nuance with the Rh factor: often the term universal recipient is given as AB positive, since the Rh antigen (D) affects compatibility as well. But for the ABO system alone, AB is the universal recipient.

The key idea is compatibility of surface antigens and antibodies in blood. A person is a universal recipient in the ABO system when their blood plasma lacks both anti-A and anti-B antibodies, so they won’t attack donor red cells of any ABO type. Type AB blood has both A and B antigens on the red blood cells and, importantly, no anti-A or anti-B antibodies in the plasma. This means they can receive red blood cells from any ABO type—A, B, AB, or O—without mounting an immune attack.

In contrast, someone with type O blood has no A or B antigens on their cells but their plasma contains both anti-A and anti-B antibodies, so they can only receive from type O. Type A blood has anti-B antibodies, so it can receive from A or O, but not from B or AB. Type B blood has anti-A antibodies, so it can receive from B or O, but not from A or AB.

Note the nuance with the Rh factor: often the term universal recipient is given as AB positive, since the Rh antigen (D) affects compatibility as well. But for the ABO system alone, AB is the universal recipient.