An extensive literature review focusing on current laboratory techniques and challenges in the diagnosis and management of alloimmunization and hemolytic disease of the fetus and newborn (HDFN) prevention was recently published in Bioscientia Medicina: Journal of Biomedicine & Translational Research.
The authors of the review stated that though current methods of screening for antibodies are effective, additional screening to detect antibodies that directly bind to erythrocyte antigens is needed to aid in diagnosis and treatment.
Alloimmunization is a medical term referring to the production of antibodies (alloantibodies) against a specific molecule (antigen) present in other human beings. Red blood cells (RBCs) have many different antigens on their surface, which are not shared by all humans.
Learn more about HDFN testing and diagnosis
When a woman enters contact with RBCs with different antigens than her own, she can become alloimmunized against those antigens. In a future pregnancy, alloimmunization can lead to HDFN only if the fetus carries the specific antigen that alloantibodies target.
“Alloimmunization occurs when an individual is exposed to foreign RBC antigens, typically through transfusion, transplantation or pregnancy,” the authors wrote.
The incidence of alloimmunization varies and depends on factors such as ethnicity, previous transfusions, and pregnancy. Approximately 0.5% to 1,5% is alloimmunized. Special populations that undergo transfusions frequently, such as persons with sickle cell disease or thalassemia, could have an incidence of alloimmunization reaching 50%.
Due to the dangers associated with alloimmunization, adequate pre-transfusion testing is of the utmost importance. Currently available techniques include the tube, gel and solid phase adherence methods.
Not all alloantibodies are the same; some antibodies are more likely to produce a severe immune reaction than others. Alloantibodies that target the RhD antigen are the ones most commonly associated with severe HDFN, while alloantibodies against ABO antigens tend to produce milder immune reactions.
The above-mentioned tests only detect the presence of anti-RBC antibodies. Further testing is needed to identify the antigen against which these antibodies are directed. In recent years, automated platforms have decreased the incidence of human error.
“The detection of antibodies that directly bind to erythrocyte antigens is a critical point in compatibility testing. This examination is one of the efforts to reduce the occurrence of hemolytic transfusion reactions,” the authors wrote.
