High-voltage electron microscopy of normal and irreversibly sickled red blood cells

A high-voltage electron microscopic study of normal red cells and irreversibly sickled red cells (ISCs) was conducted. Comparison with intact, critical-point dried red cells revealed that the ISC fraction could always be identified because of the presence of numerous echinocytes. Examination of the unsealed ghosts after incubation in 3,3'-diaminobenzidene (DAB) to detect hemoglobin (Hb) bound to the plasma membrane revealed that Hb adhered to the cytoplasmic surface of the ISC membrane. The Hb was concentrated in the surface projections of the echinocytes and also was seen as granules associated with the filamentous substructure of the plasma membrane. The role of this adherent Hb in exerting a transmembrane effect to alter the surface properties of the cell is discussed.