Blood Transfusion Reaction is a Type of Allergy

Hypersensitivity Due to Incompatible Blood Donation

Apr 13, 2009 Jitendra Rathod

Incompatible blood transfusions may lead to reactions ranging from mild to life threatening. The manifestations may be either immediate or delayed.

Blood is an important tissue of our body functioning as a carrier of nutrients and as an exchanger of gases (oxygen and carbon dioxide) to each and every cell of the human body. It is the only human tissue which is most frequently transplanted from a donor to a recipient. But as is true with any tissue of the human body, it is imperative that it be compatible with the recipient’s body before it can be transplanted.

Blood grouping is routinely done to check blood group compatibility. What is actually checked is compatibility with regards to only two blood group systems: ABO and Rh. This is because these two are the systems possessing the strongest antigens and antibodies and are, hence, more likely to give a strong incompatibility reaction. A person possessing A Rh positive blood group should be given blood of another A Rh positive individual only.

Before Karl Landsteiner discovered the ABO system in the early part of the twentieth century, transfusions were rarely performed and if they were performed, there were disastrous results. Discovery of the ABO system and the Rh system has made blood transfusion an every day matter. And thus with routine blood grouping, immediate transfusion reactions have become exceedingly rare.

Immediate transfusion reaction

But when they do occur, they result in massive hemolysis (rupture of red blood cells) of the transfused red blood cells. The manifestations of this hemolysis include hemoglobinuria(hemoglobin in urine) and conversion of some hemoglobin to bilirubin (which is toxic at high levels). Typical symptoms include chills, nausea, fever, clotting within blood vessels and lower back pain. Treatment involves immediate termination of the transfusion and continuous maintenance of urine flow using a diuretic.

Delayed transfusion reaction

This type of reaction is often seen in individuals who have received repeated blood transfusions. Even though, the individual is given blood which is ABO and Rhcompatible, there are many other minor systems which are still incompatible. The only other person whose blood will never give you any transfusion reaction, no matter how many times it is transfused in your body, is your identical twin. Otherwise, there is always some incompatibility between bloods of different individuals.

Delayed hemolytic transfusion reactions develop between two and six days after transfusion. Symptoms include fever, low hemoglobin, increased bilirubin, mild jaundice and anemia. Free hemoglobin is usually not detected in the plasma or urine because unlike immediate transfusion reactions where hemolysis occurs in the blood vessels, hemolysis in case of delayed transfusion reactions occurs in extravascular (outside the blood vessels) sites.

To understand what an allergy is, click here.

Source: Immunology by Goldsby, Kindt, Osborne and Kuby. (5th Ed.) W H. Freeman.

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