By Billie Rubin, reporting from the labs of Stanford Blood Center
Certain patients receiving blood transfusions require specific compatibility testing beyond the ABO type and Rh factor that we commonly hear about, (A+, A-, B+, etc.). This is typically the case with those who have been transfused many times, such as sickle-cell anemia patients.
When a hospital’s transfusion services department can’t find compatible blood for a patient, they send a sample of the blood to a blood bank reference lab. These labs have many tests they use to help identify the antibodies that are causing the incompatibility.
Interestingly, one tool these reference labs have is the use of certain fruit enzymes to study red blood cell (RBC) antigens (there are hundreds and hundreds of them in addition to the A & B antigens). This can be important in the serological identification of a patient’s antibodies in order to find them compatible blood. Some of these fruit enzymes (bromelin from pineapples, papain from papayas) can cleave an RBC antigen’s structure at specific points and this would give the labs clues as to their identity and assist in finding the right blood for the patient.