ABO Blood Group System - Transfusion Reactions

Transfusion Reactions

Due to the presence of isoantibodies against non-self blood group antigens, individuals of type A blood group immediately raise anti-B antibodies against B-blood group RBCs if transfused with blood from B group. The anti-B antibodies bind to B antigens on RBCs and cause complement-mediated lysis of the RBCs. The same happens for B and O groups (which raises both anti-A and anti-B antibodies). However, only blood group AB does not have anti-A and anti-B isoantibodies. This is because both A and B-antigens are present on the RBCs and are both self-antigens, hence they can receive blood from all groups and are universal recipients.

As far as transfusion compatibility is concerned, it is not strictly as simple as matching A, B, and O groups. In other words, no individual will ever receive a blood transfusion based on the ABO system alone. The rhesus factor must also be considered. Together, the rhesus factor and ABO grouping are the two most important compatibility factors to consider. An individual may be Rh+ or Rh-. In simpler terms, if an individual is blood type A and positive for the rhesus factor, then he or she is deemed "A+".

* Type AB+ is the universal recipient: Although those with AB blood type may be referred to as universal recipients, in actuality, type AB+ blood is that of the universal recipient, whereas type AB- is not. This is an important distinction to make.

** Because A-, A+, B-, B+, AB-, AB+, O- and O+ individuals can all receive blood from donors of type O- blood, an individual with type O- blood is deemed a universal donor. In a similar manner, O+ is not the universal donor blood type.

One caveat to this axiom of 'universal donor' is that this applies to packed RBCs, and not to whole blood products. Using the first table, type O carries anti-A and anti-B antibodies in the serum. To transfuse a type A, B, or AB recipient with type O whole blood would produce a hemolytic transfusion reaction due to the antibodies found in the serum of whole blood.

No antibodies are formed against the H antigen, except in those individuals with the Bombay phenotype.

In ABH secretors, roughly 80% of the human population, ABH antigens are secreted by most mucus-producing cells of the body interfacing with the environment, including lung, skin, liver, pancreas, stomach, intestines, ovaries, and prostate.