Transfer of GPI-Linked Proteins to Transfused Patients With Paroxysmal Nocturnal Hemoglobinuria

This study will examine blood cells of patients with paroxysmal nocturnal hemoglobinuria (PNH) after they receive a blood transfusion to determine if certain proteins (GPI-linked proteins) in the transfused blood transfer to the patient's blood cells. GPI-linked proteins, which are normally present on red cells and regulate red cell survival, are absent in patients with PNH. Their lack is believed to account for the premature destruction of red blood cells in these patients, resulting in a low hemoglobin and hematocrit. Patients may experience fatigue, flank pain and other symptoms, requiring treatment with blood transfusion.

Patients with PNH 18 years of age or older with group A1 blood who require at least three units of red cells and who have not been transfused with group O blood within the last 3 months may be eligible for this study.

Participants will come to the NIH Clinical Center for the following procedures:

• Interview about the severity of their anemia-related symptoms
• Blood test
• Blood transfusion, if required. Patients will be transfused with compatible group O blood. The donor blood will be washed (rinsed with a salt solution) until it is 99% free of donor plasma. Group O blood is given instead of group A1 in order to be able to distinguish the patient's cells from the transfused cells.

Blood samples of 3 teaspoons each will be drawn 1 day, 1 week, and 3 weeks after the transfusion. These samples may be collected by the patient's doctor locally and sent to NIH by mail.

If it is found that GPI-linked proteins transfer to the patient's cells, the study will also examine how long the proteins remain attached and will assess whether the proteins are functional and prevent cell destruction.