Successful use of eculizumab for treatment of an acute hemolytic reaction after ABO-incompatible red blood cell transfusion

BACKGROUND: Transfusion of ABO major-incompatible red blood cells (RBCs) can activate the complement system and can cause severe and even lethal acute hemolytic reactions. The activation of the complement system with formation of C3a and C5a (anaphylatoxins) and the release of hemoglobin from the lysed RBCs are thought to mediate clinical signs like fever, hypotension, pain, and acute renal failure. Therapeutic inhibition of the complement cascade in case of ABO-incompatible RBC transfusion would be desirable to ameliorate the signs and symptoms and to improve the outcome of the reaction.

STUDY DESIGN AND METHODS: A patient with blood group B was erroneously transfused with a unit of group A2 RBCs. Within 1 hour after transfusion she received eculizumab, a monoclonal antibody that binds to the complement component C5 and blocks its cleavage. Clinical and immunohematologic observations are reported here.

RESULTS: Hemoglobinemia and hemoglobinuria were present for several hours after transfusion, but she developed no hypotension, no renal failure, and no disseminated intravascular coagulation. As shown by flow cytometry, group A cells survived in the peripheral blood for more than 75 days. No immunoglobulin G was detectable by column agglutination technique on these cells.

CONCLUSION: A low isoagglutinin titer and blood group A2 of the erroneously transfused cells most likely were the reason for the absence of clinical signs during and immediately after the ABO-incompatible transfusion. In the further course, eculizumab successfully protected the incompatible RBCs from hemolysis for several weeks.