Alloantibodies against the Rh and Kell antigens appear to be the most prevalent in pregnancies complicated with hemolytic disease of the fetus and newborn (HDFN), according to a recently published study in Hematology, Transfusion, and Cell Therapy.
The study authors aimed to assess the most common antibodies in maternal plasma and to determine which of them cause HDFN. The study included data from 75 studies worldwide, including over 13000 cases.
Results showed that anti-RhD antibodies were responsible for 35% of cases, making it the most commonly associated with HDFN. Anti-kell antibodies were responsible for approximately 15% of cases, followed by anti-E (11% of cases).
Learn more about HDFN causes and risk factors
“Alloantibodies usually form after exposure to non-self-antigens due to a transfusion or transplantation, or when a pregnancy results in sensitization creating antibodies against RBC antigens,” the authors wrote.
An antigen is any molecule capable of being recognized by an immune cell and producing an immune response.
Human red blood cells (RBCs) express many different antigens on their surface. They do not trigger an immune response in normal conditions because they are recognized as part of the body. However, when the immune system contacts foreign RBCs with different antigens , it produces antibodies against them.
Women who receive emergency blood transfusions with non-compatible blood or who carry fetuses with a different blood type can develop these antibodies (alloimmunization) and suffer from HDFN in a subsequent pregnancy.
Researchers remarked that most of the evaluated studies were from Europe, America, and Asia, with regions such as Africa and South America being underrepresented. Therefore, future research in these regions is recommended.
“Knowing the physiopathology of alloantibodies is also helpful in understanding the evolution of HDFN,” the authors stated. “Furthermore, considering the high diversity of blood group alleles, there is a need to study the frequency of pregnant alloimmunization and HDFN in different populations.”
