Immunodetection of TfR in exosomes released from control and PNH reticulocytes. Samples (50 μg protein) were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in a 10% acrylamide gel and proteins were transferred to nitrocellulose. TfR was detected by Western blot using a MoAb (OKT9) raised against human TfR and an alkaline phosphatase-conjugated rabbit antimouse antibody. The molecular mass (kD) standards are indicated on the right.