What might happen if a patient is transfused with a blood unit that matches an antibody they have?

When a patient is transfused with a blood unit that matches an antibody they have, an anamnestic response may occur, leading to a transfusion reaction. This reaction happens because the patient’s immune system recognizes the transfused blood cells as foreign due to the presence of the corresponding antigen on the red blood cells. This immune recognition triggers the production of antibodies against those specific antigens, which can result in hemolysis (destruction of red blood cells), fever, chills, or other serious complications.

In a case of anamnestic response, the patient has been previously sensitized to a particular antigen, often from a prior transfusion or pregnancy. Upon subsequent exposure to the same antigen through transfusion, a rapid and stronger immune response is generated. This is why the risk of transfusion reactions is particularly significant when there is a known history of sensitization to a specific antigen.

The other potential outcomes, such as an apheresis response, lifesaving supplementation, or no significant reaction, do not accurately reflect the potential immunological consequences of transfusion in the presence of specific antibodies. In cases where there is a pre-existing antibody against a transfused antigen, the likelihood of a transfusion reaction increases significantly, emphasizing the importance of careful cross-m