Electron microscopic studies on blood smears and hemoglobin in sickle cell disease

Abstract

A replication method for the electron microscopic examination of blood cell surfaces and purified hemoglobin is described. Significant structural alterations were observed in erythrocytes and serum in blood smears from patients with sickle cell disease. Examination of hemoglobin by this method revealed rod-shaped crystals containing four internal electron-dense strands with dimensions which were in striking agreement with the length of the peptide chain and distance between iron atoms reported by other workers from X-ray diffraction studies. Therefore, it is believed that the crystals observed in this study represent molecular aggregates of hemoglobin. Although three dimensional crystals were present along cell surfaces and in close proximity to erythrocytes in blood smears from patients with sickle cell disease, they were not present within cells. It is suggested that an interface effect between hemoglobin and the cell membranes may be the mechanism by which sickling occurs. Studies of dilute solutions of hemoglobin which were dried on formvar films and examined in the electron microscope without further preparation showed structures containing four electrondense globules. These latter units were considered to represent hemoglobin molecules which had expanded by dissociation.