The first case of severe acute hemolytic transfusion reaction caused by anti‐Sc2

摘要

BACKGROUND Alloantibodies to the low‐frequency antigen Scianna‐2 (Sc2) have been implicated in cases of hemolytic disease of the fetus and newborn but never in hemolytic transfusion reactions (HTRs); thus, the clinical significance of anti‐Sc2 has yet to be fully addressed. STUDY DESIGN AND METHODS A 26‐year‐old woman with thalassemia presented rigors, fever, nausea, abdominal pain, and hemolytic biochemistry after exposure to 75 mL of plasma‐reduced red blood cells (RBCs). The RBC unit was issued by electronic crossmatch but was 3+ incompatible on recrossmatch by gel indirect antiglobulin test (IAT). The patient had anti‐Sc2 previously identified, but considered to be clinically insignificant. The transfusion history was reviewed and a monocyte monolayer assay (MMA) was performed. RESULTS The patient was investigated for a RBC reaction 9 years prior, when she developed symptoms of HTR. The RBC unit was crossmatched by immediate spin due to consistent screen negativity. Full crossmatch found the RBC 1+ incompatible by gel IAT with both pre/post samples, while direct antiglobulin test was negative (pre) and 1+ immunoglobulin G positive (post). The antibody remained unidentified and she was committed to gel IAT crossmatch. Two‐years later, the specificity to Sc2 was deduced when one RBC unit was found 3+ incompatible. Finally, the transfusion reaction reported herein occurred when she received by happenstance RBCs from the same donor who was associated with the remote reaction 9 years earlier. MMA yielded highly positive phagocytic indices only for Sc2+ RBCs, including the donor's RBCs that triggered the severe HTR. CONCLUSION This is the first case of HTR caused by anti‐Sc2 confirmed by clinical findings and MMA.