Coexistence of autoantibodies and alloantibodies to red blood cells due to blood transfusion

BACKGROUND: Autoantibodies (AUTO) to red blood cells (RBCs) are frequently associated with alloantibodies (ALLO). The mechanism for the coexistence of these antibodies is obscure. STUDY DESIGN AND METHODS: Between August 1998 and June 2006, all in- and outpatients of the Charite University Hospital, Berlin, with detectable AUTO were included in this study. Serologic examination was performed with standard techniques for the detection of RBC antibodies. RESULTS: A total of 717 patients were found to have AUTO, with ALLO observed in 200 of these patients (28%). The history of antibody production could be evaluated in 98 of the 200 patients. Both AUTO and ALLO were due to RBC transfusion in 73 cases (75%) and peripheral blood progenitor cell transplantation in 6 cases (6%). Nine (9%) patients were primarily alloimmunized and subsequently developed AUTO. The remaining 10 (10%) patients were primarily autoimmunized and later developed ALLO. Only 6 of these patients had chronic idiopathic autoimmune hemolytic anemia. CONCLUSION: The majority of AUTO associated with ALLO appears to be due to RBC transfusion that must be recognized as a major cause for autoimmunization.