[Controlled immunoglobulin therapy in immune hemolytic anemia by positive pool immunoglobulin fluorescence test]

An Italian boy with homozygous beta-thalassemia showed a shortening of transfusion intervals at the age of three years. He had a positive direct antiglobulin test (DAT) because of C3d-loaded red blood cells without any detectable erythrocytic antibody. Serologic investigations indicated a recent EBV infection. Pool immunoglobulin fluorescence test (PIT) revealed a loading of red blood cell membranes with antigens. Oral prednisone therapy did not show any effect. After a single infusion of 400 mg immunoglobulin per kg body weight decrease of hemoglobin concentration slowed down to the rate before crisis. DAT and PIT became negative. The immune hemolytic crisis was possibly due to erythrocyte loading with EBV antigen that caused activation of the alternate complement pathway. Detection of antigen loaded red blood cells by PIT suggested a immunoglobulin therapy in order to coat the structures promoting hemolysis. Thus, a positive PIT seems to be a criterion for successful application of immunoglobulins in immune hemolytic anemia.