Determinants of red blood cell alloantibody detection duration: analysis of multiply alloimmunized patients supports peritransfusion factors

BACKGROUND Alloimmunization to red blood cells (RBCs) can cause serious transfusion reactions and complicate the search for compatible blood products. Alloantibodies can be detected for periods ranging from a few days to several years, yet the mechanisms controlling the duration of detectability remain unknown. We studied the detection durations in patients forming multiple antibodies to investigate whether the duration is more strongly determined by conditions present at the time of each transfusion (peritransfusion factors) or by more stable patient-specific factors likely to persist across transfusions. STUDY DESIGN AND METHODS We studied retrospective medical records for alloimmunized patients at Massachusetts General Hospital and Brigham and Women's Hospital (1461 patients; 2187 antibodies). RESULTS Antibodies discovered simultaneously in a patient shared similar fates: 76% persisted through the last screen or first became undetectable during the same screen. Simultaneously identified antibodies were also more persistent than sequentially identified antibodies (mean, 9.2 months vs. 4.9 months; p < 10−3). Within a patient, antibodies discovered simultaneously tended to be detected for similar periods of time (mean difference, 25 days), compared to the detection period for sequentially discovered antibodies (107 days, p < 10−3). CONCLUSIONS The similarity in detection duration of simultaneously identified antibodies suggests that peritransfusion factors are important determinants of alloantibody detectability and duration. We also find some evidence that detection durations for sequentially identified antibodies are also more highly correlated than those for randomly selected antibodies across all patients, suggesting that patient-specific factors also play a role in determining alloantibody persistence.