An acute hemolytic transfusion reaction due to anti-IH in a patient with sickle cell disease

A hemolytic transfusion reaction (HTR) due to anti-IH is reported in a patient with sickle cell disease (SCD).

An 18-year-old woman with SCD and a complete phenotype on file had been identified as group B-positive with negative antibody-screening tests and had received 1 unit of packed RBCs. Ten days later, she was readmitted in painful crisis with a Hb of 4.2 g per dL. Antibody-screening tests and panel cells were positive at all test phases with a negative autocontrol, which suggested alloantibodies. Phenotypically matched group O RBCs were issued emergently. After the transfusion of 100 mL, the patient had an HTR with chills, fever, and tachycardia and laboratory findings of hemoglobinemia, hemoglobinuria, and negative DATs. A high-titer, IgM anti-IH with a high thermal amplitude (reactive with group O, but not group B RBCs at 37 degrees C) was identified. Autologous RBCs appeared to have normal I antigen expression, but less H antigen than pooled group B RBCs. She was given group B RBCs, uneventfully, by use of a blood warmer.

This is a rare case of anti-IH as the cause of a HTR, as a serologic problem that may be seen in SCD, and as an autoantibody that may mimic an alloantibody. Ironically, this HTR resulted from the effort to provide phenotypically matched RBCs, which necessitated the selection of group O RBCs.