Shape stabilizing agents protect erythrocytes against freeze-thaw damage

In this work we demonstrate that physicochemical modification of the erythrocyte membrane by shape stabilizing agents increases cryostability. Three different classes of shape stabilizing agents were examined for their cryoprotective action: the lectins (wheat germ agglutinin and concanavalin A), sulfhydryl oxidizing agents (diamide and N-ethylmaleimide) and chemical fixatives (glutaraldehyde). All classes of agents reduced freeze-thaw damage after freezing erythrocytes to -20 degrees C in a concentration and time dependent manner. The cryoprotectant action of these agents was compared with their ability to stabilize erythrocyte shape and affect membrane deformability. All shape stabilizing agents with the exeption of concanavalin A induced a significant decrease in membrane deformability. Anti-glycophorin antibody and Phaseolus vulgaris lectin increased membrane rigidity but did not act as shape stabilizing agents or cryoprotectants. Thus, the ability to alter membrane deformability, may not by itself result in shape stabilization or cryoprotection. The ability to stabilize red cell shape may however result in increased cryostability.