Rhesus alloimmunization following intensive plasma exchange

A 17-year-old woman was admitted to the hospital for the treatment of rapidly progressive systemic lupus erythematosus. She failed to improve when treatment with cyclophosphamide and prednisone and, therefore, was treated with intensive plasma exchange. A total of 24 liters of plasma was exchanged during six separate procedures over an 8-day period. The patient, who was blood group B Rh negative (Cde/cde), was found to have an IgGanti-D antibody reacting at a titer of 16 by the indirect antiglobulin technique 6 weeks after the first plasma exchange procedure. The titer of this antibody subsequently rose to 512. This patient, who had neither been pregnant nor received any blood products other than the plasma used during the plasma exchange, was presumably immunized by Rh positive red cells or stroma present in the transfused plasma. It is estimated that the patient received approximately 1010 Rh positive cells, or approximately one ml of packed red cells-a quantity sufficient to cause Rhesus alloimmunization.