Methods of RBC Alloimmunization to ABO and Non-ABO Antigens, and Test Methodologies

Abstract Arguably the most clinically vital aspect of transfusion medicine is ensuring that compatible blood products are transfused to patients. Consequently, while the previous chapter provides a general overview of immunologic concepts, a deeper understanding of mechanisms underlying RBC alloimmunization and general familiarity with commonly encountered RBC antigens and antibodies is essential as well. Beyond the basic level of ABO compatibility, there are numerous other antigens and alloantibodies that are capable of causing both acute and delayed hemolytic transfusion reactions, and may render it progressively more difficult to obtain compatible RBC units for a given patient. Furthermore, this may have broader implications for compatibility in potential solid organ or hematopoietic progenitor cell transplants in patients at a future date. This chapter first will discuss the genetics underlying the ABO blood groups, as well as antibodies formed against them. We will then discuss overview of the most clinically significant RBC antigens and antibodies formed against them, maintaining a focus on implications for compatible RBC transfusions and considering the prevalence of these antigens in various populations, and highlighting the characteristics of these antibodies. Finally, we will touch briefly on the three most commonly employed methods of antibody detection used in blood banks today, and close with a look ahead towards molecular typing methods, which represent a new and exciting avenue in RBC antigen identification and potential alloimmunzation capability, which may assist in prevention of incompatible RBC transfusions in complex clinical scenarios.