N-Acetylneuraminic Acid Deficiency in Erythrocyte Membranes: Biophysical and Biochemical Correlates

The electrochemical and rheologic behaviors of red blood cells (RBCs) from a patient with acquired polyagglutinability were studied. The N-acetylneuraminic acid content of the RBCs averaged less than one-half normal. The majority of the patient’s RBCs (over 90%) showed a reduction in electrophoretic mobility and a decrease in binding of positively charged colloid with a widening of the charge-free areas, but a small population exhibited normal surface charge density. Dextran 40, which does not induce significant aggregation of normal RBCs, caused the patient’s RBCs to form rouleaux. Dextran 80 induced a stronger aggregation of the patient’s RBCs than that of normal RBCs. The increased tendency of the patient’s RBCs to be aggregated by macromolecules was associated with an elevation of blood viscosity. This study on a clinical patient has provided evidence for the conclusions previously derived from experimental studies that the stability of RBC aggregation depends upon a balance between macromolecular bridging force and electrostatic repulsive force and that alterations in RBC surface charge may affect cell aggregation and blood viscosity.