Delayed Hemolytic Transfusion Reaction in a Patient With Sickle Cell Disease and the Role of the Classical Complement Pathway: A Case Report.

A 14-year-old female patient with sickle cell disease developed a severe delayed hemolytic transfusion reaction (DHTR) leading to multiple transfusions and intensive care management. To better understand the extent to which the classical complement pathway was contributing to her DHTR, we utilized the complement hemolysis using human erythrocytes (CHUHE) assay and the classical complement pathway inhibitor, PIC1. Residual discarded de-identified plasma and erythrocytes from the patient obtained from routine phlebotomy was acquired. These reagents were used in the CHUHE assay in the presence of increasing concentrations of PIC1. Complement-mediated hemolysis of the patient's erythrocytes occurred in her plasma and complement permissive buffer. Increasing concentrations of PIC1 dose-dependently inhibited hemolysis to levels found for the negative control - complement inhibitor buffer. Complement-mediated hemolysis was demonstrated by the CHUHE assay for this patient with sickle cell disease and severe DHTR. PIC1 inhibition of hemolysis suggested that the classical complement pathway was contributing to her DHTR.