Red Blood Cell Alloimmunization after Blood Transfusion

Current pretransfusion policy requires the patients’ serum to be tested for the presence of irregular red blood cell antibodies. In case of an antibody, red blood cells lacking the corresponding antigen are transfused after an antiglobulin crossmatch.The aim of the studies in this thesis is primarily to investigate whether this policy should change to improve transfusion safety.This thesis explores the risk on red blood cell alloimmunization after blood transfusion in oncohematologic patients and in patients who already formed antibodies after aprevious transfusion event. Furthermore, the risks of current pre-transfusion testing with regard to antibodies to low incidence antigens, timing of antibody testing and antibody persistence were studied.From these studies it was concluded that 1. oncohematologic patients have a high chance on developing antibodies despite immunosuppressive therapy, 2. patients with antibodies have a 20-25 times increased risk for additional antibodies after subsequent transfusions, compared to primo antibody formation, and preventive measures should be considered, 3. antibodies to low incidence antigens are common in immunized and non-immunized patients, 4. timing of antibody screening after transfusion influences the number as well as the specificity of the antibodies detected and 5. antibodies may become undetectable over time compromising transfusion safety.