Hemolytic transfusion reaction due to anti-IH

Anti-IH is usually a clinically insignificant antibody that may complicate a serologic workup. However, it can occasionally cause hemolysis. We report a rare case of acute hemolysis caused by anti-IH.

A 60-year-old man with a long history of chronic myelomonocytic leukemia and anemia, blood group A, D+ was found to have an unidentified antibody on serologic workup. He received an A, D+ red blood cell (RBC) unit that was crossmatch compatible by immunoglobulin G indirect antiglobulin test and then experienced an acute hemolytic transfusion reaction with fever, hemoglobinuria, and acute renal failure. The antibody was later identified as an anti-IH with a wide thermal amplitude. The transfused RBCs were later typed as A(2). The patient was subsequently typed as an A(1) individual. The patient recovered completely from the effects of this reaction and was transfused with A(1) RBCs over the next few days with no adverse effect.

Anti-IH, which is usually clinically insignificant and often found in A(1), B, and A(1) B individuals, can, on rare occasions, cause acute hemolytic transfusion reactions, especially when an A(2) unit is transfused to an A(1) patient.