Editorial: Of Acanthocytes, Spurs, Burrs and Membranes

By ROBERT SILBER I N 1950 BASSEN AND KORNZWEIG1 described an unusual morphologic distortion of the human erythrocyte in two siblings with retinitis pigmentosa, neurologic abnormalities, and a history of steatorrhea. The red cells showed thorny excrescences when examined in suspension or on stained smears. Twenty other cases were reported over the next 18 years. In 1958 Jampel and Falls2 documented the low plasma cholesterol and suggested that this disorder, by now designated with the euphonious but inaccurate term “acanthrocytosis,” was a disease of lipid metabolism.2 The name was corrected to acanthocytosis ( from the Greek word acanthos-spine ) one year later. The important observation that the light density, beta lipoprotein was not detectable in the plasma of these patients led to the concept of a plasma abnormality, affecting proteins, lipids or the interaction between these coinpounds.4 The names beta lipoprotein deficiency or abetalipoproteinemia may be closer to the genetic abnormality leading to the disease than the tenn acanthocytosis. The ratio of sphingomyelin to lecithin is decreased in the patients’ plasma.a This abnormality probably results in the erythrocyte lipid defect; in contrast to normal erythrocytes where lecithin is the predominant membrane phospholipid, acanthocytes contain more sphingomyelin and less lecithin.6 The finding of a low lecithin content in acanthocytes was the first example of a lipid alteration in the human erythrocyte.#{176} The importance of the plasma environment was documented by Ways and Simon, who demonstrated that the striking increase in autohemolysis observed in this disorder could be corrected by a factor associated with lipid fractions of normal serum.7 Later studies indicated that the deficiency of a-tocopherol in the plasma may account for the increased autohemolysis.8 In the absence of tocopherol, the red cell membrane becomes susceptible to oxidative damage by peroxides.9’1 \Vithin the last ten years, spinous erythrocytes have been described in a variety of clinical disorders including uremia, microangiopathic hemolytic anemia, thrombotic thrombocytopenia purpura, pyruvate kinase deficiency, and carcinoma.1216 Of particular interest is the report of Smith and covorkers17 who described a cirrhotic patient with “spur” cells and hemolytic anemia in which the plasma could induce the morphologic abnormality in normal erythrocytes. Conversely, when the patient’s erythrocytes were in-