Haemolysis after treatment with intravenous immunoglobulin due to anti-A

Background: Intravenous immunoglobulin (IVIG) is used to treat an increasing number of conditions. IVIG contains immunoglobulin G (IgG) directed against many targets, including red blood cell (RBC) antigens. Methods/materials: We report on three patients identified within a 7-month period in a single institution who developed haemolysis because of passively transferred anti-A. Results: The patients were a 34-year-old A (non-A₁) D-positive male with aplastic anaemia, a 61-year-old A₁ D-negative female with myasthenia gravis and a 57-year-old AB D-positive female lung transplant recipient. The haemoglobin decreased from 11·1 to 5·3 g dL^-1 over 2 days, 12·8 to 7·8 g dL^-1 over 6 days and 7·8 to 6·0 g dL^-1 over several hours, respectively. All three patients had a negative antibody screen, positive direct antiglobulin test for IgG only and an elution containing anti-A₁ reactivity. The patients were transfused with O RBC with an appropriate rise in haemoglobin. Conclusion: These cases illustrate the potential severity of haemolysis after IVIG because of passively transferred antibodies to blood group antigens. Lack of recognition of IVIG as a cause for haemolysis by clinicians may be further confounded if routine testing fails to detect the passively transferred ABO blood group antibodies.