Final answer:
A transfusion reaction is a subacute hypersensitivity to foreign red blood cells that occurs when a person receives a transfusion of incompatible blood. Symptoms include fever, chills, itching, hives, and low blood pressure.
Step-by-step explanation:
A transfusion reaction is a subacute hypersensitivity to foreign red blood cells. It occurs when a person receives a transfusion of blood that is not compatible with their own blood type. For example, if a person with type B blood receives a transfusion of type A blood, their anti-A antibodies will bind to and agglutinate the transfused red blood cells. This can lead to a range of symptoms such as fever, chills, pruritus, urticaria, and hypotension.