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Medical Definition of Blood transfusion reaction
1. This refers to an immune response against transfused blood cells. Antigens, on the surface of red blood cells, are recognised as foreign proteins and can stimulate sensitised lymphocytes to produce antibodies to the red blood cell antigens. This triggers a complex immunological reaction that results in the destruction of the transfused red blood cell. The blood groups (A, B, AB, O) are classified on the basis of the presence of surface antigens on the red blood cell. Type A blood has A antigens. The plasma component of the blood contains the antibodies against all other blood group antigens other that its own. Another type of surface antigen is known as Rh factor. Rh factor is either present (Rh positive) or absent (Rh negative). Rh compatibility is another requirement for blood transfusion. Symptoms and findings of a transfusion reaction include flank pain, fever, chills, bloody urine, rash, low blood pressure, dizziness and fainting. (27 Sep 1997)