Amongst the ABO and RH(D) RBC (Red Blood Cell) antigens, there are mor than 300 other antigens known on Red Blood Cells. It is known too, that, after the contact with foreign Red Blood Cells - e.g after a transfusion or after pregnancy, some patients will develop special antibodies to non-ABO/Rh(D) antigens that they lack on their own RBCs (alloantibodies). In the general hospital generation it has a probability of 1-2 percent, but it is much higher in the patients group of chronically tranfused persons and in multiparous females. Some alloantibodies may be clinically significant, causing a hemolytic transfusion reaction if the patient receives a transfusion of RBCs that have the corresponding antigen(s). Therefore, pre-transfusion testing routinely includes tests to detect clinically significant RBC alloantibodies and to select RBC units that lack the corresponding antigen(s).
To avoid significant and critical reactions, it will be helpful to know whether the RBC units are suitable relating to significant alloantibodies of a prospective transfusion recipient. Blood collection establishments and transfusion services can locate suitable RBC units by randomly testing units from their inventory; however, the process can be time consuming, labor and resource intensive, and difficult to complete in emergency situations. Therefore, a labeling with historical antigen typing results will be helpful for a preselection of the donations. In January, the FDA thus published a Draft Guideline for Industry "Labeling of Red Blood Cell Units with Historical Antigen Typing Results". This document should give establishments that collect blood and blood components for transfusion recommendations for labeling RBC units with non-ABO/Rh(D) antigen typing results obtained from previous donations (historical antigen typing results). The document is published for comment purposes only.