[Transfusion of patients with autoimmune hemolytic anemia]

Autoimmune hemolytic anemia (AIHA) is caused by the generation of autoantibodies against red cells. Sometimes, the destruction of red cells occurs in the intravascular space following the autoantibody-mediated activation of the complement cascade. More frequently, extravascular hemolysis occurs when macrophages phagocytose autoantibodies and complements bearing red cells. The direct antiglobulin test results (DAT) are usually positive. When the serum of patients with AIHA frequently reacts with all normal red cells, it is impossible to find compatible blood for transfusion. It is necessary to adsorb autoantibodies by autologous or allogeneic red cells for detecting alloantibodies in patients with AIHA. In addition, it is essential to accurately detect alloantibodies and intentionally avoid the generation of new alloantibodies for performing safer transfusion in the future. Although transfusion of phenotypically matched blood is desirable, it is challenging to obtain such blood in time. Moreover, the transfusion of partially phenotypically matched blood (ABO, D, C, E, c, e, Jk^a, Jk^b) and the exclusion of alloantibody-related phenotype appear to be appropriate to avoid the severe transfusion reaction in the clinical setting. Furthermore, small volume, slow, and inevitable transfusion is recommended to avoid unexpected complications. In cases of cold reactive AIHAs, the application of blood warmer is recommended for transfusion.