Immunohematological Investigation of Fatal Hemolysis in Long-Duration Autoimmune Hemolytic Anemia with Anti-S and Anti-Wr^a Alloantibodies: A Case Report

Autoimmune hemolytic anemia (AIHA) is a serious condition characterized by the severe hemolysis caused by increased levels of autoantibodies that specifically attack erythrocytes. Autoantibodies present difficulties in identifying alloantibodies, increasing the likelihood of hemolytic transfusion reactions (HTRs). In this report, we presented a rare and severe case of fatal HTRs caused by alloantibodies known as anti-S and anti-Wr^a in a female patient who had been suffering from hemolytic anemia for four decades. The patient's blood group type showed a significant inconsistency, later verified as AB CcDee by serologic tests. The antibody identification revealed unique patterns of anti-S and anti-Wr^a antibodies, with a noticeable disparity in agglutination intensity rated as 3+. Consequently, her erythrocytes were subjected to a freeze-thaw process, and the eluate showed robust pan-reactivity. The patient's MNS and Diego blood systems were analyzed using genetic sequencing, which confirmed the absence of the S or Wr^a antigen. However, the presence of a weakly positive S antigen in the serological result indicated the possibility of transfusion of leukocyte-poor red blood cells (LPRs) that carry the S antigen. As a result, the patient started receiving LPRs with the same phenotype, while avoiding S and Wr^a antigens. In addition, we evaluated the patient's state and discussed the appropriate blood transfusion protocol for AIHA in this case. Medical practitioners must possess expertise in identifying autoantibodies and alloantibodies in AIHA and devising a suitable blood transfusion plan.